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Don Klipstein
Guest
Guest
Wed Sep 01, 2010 7:28 am
In <378d7949-e54d-4ac0-b8fc-956936b9beb1_at_x42g2000yqx.googlegroups.com>,
Bill Bowden wrote:
Quote:
On Aug 31, 4:38 pm, d...@manx.misty.com (Don Klipstein) wrote:
In <81685886-6c51-405d-ada2-9a0f3595c...@m17g2000prl.googlegroups.com>,
Bill Sloman wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
SNIP to this point
One particularly cute application which passed through here a while
back was with someone who was looking to drive an audio transducer at
a higher level than could be afforded by a single transistor doing
Morse "H" forever, and someone suggested using a couple of 555's with
their totem poles arranged as a full bridge, thereby driving the
transducer with about about four times the power available from the
single transistor, at the same supply voltage.
I remember that he posted back, not quite awestruck, but certainly
quite impressed with the performance increase he enjoyed from his
transducer for certainly less than a dollar's worth of parts.
Another of the 101 things a boy can do with a 555.
A low cost 8-pin IC that can be used as an inverting buffer and that
can drive some dynamic loudspeakers can get a market by making very low
cost somewhat loud things that buzz or beep. Add a mere 4 capacitors
for "best practice", can often get away with 2, and if the transducer is a
piezo one fewer still, plus only one resistor.
Some of the things that boys and girls can do with a 555 can get a
market. My father told me that engineering is an economic science.
He even told me that it is not worth spending more than $999 on a pumpkin
cannon in a pumpkin cannon contest whose 1st prize is $1K, unless the
winning position has value beyond the prize payout.
----
And you can do what?
About three?
----
Only if I washed my hands afterwards.
I think that says something!!!
(Not that I usually agree with JF, who I find/"find" to often show mean
spirit.)
I doubt if this was
the only way of solving that poster's problem, and I'd be surprised if
it was the minimum solution, but since you haven't specified the
problem solved in any detail, this is pure speculation.
---
SNIP a bit of digression
There's enough detail there for someone skilled in the art to be able
to flesh out a solution.
We don't even have the rail voltage.
Most microprocessors simpler than a Pentium need voltages that a 555
can work from. So do most logic IC families.
If the supply voltage is a low one like 3.3 volts or less, then getting
a lot of sound from an audio transducer is likely to require a buffer,
voltage boost such as with a transformer (likely requiring a buffer after
digital type stuff), or trickery that gets harder to do if the
transducer's package has to be miniaturized, especially if the transducer
is a cheap one.
In such low voltage cases, I would try out a 556 and a 40106, and in
either case I feel like I am mildly abusing them. There is also the LM386
as a nice cheap 8-pin low-parts-count audio amplifier, somewhat optimized
towards lowish supply voltages like as low as 6 volts, works not much
worse at 4.5-5.
" Bottom line, I like 555s because their cost is low, they are quick and
simple to implement, and they are *reliable* at doing many of the 101-
plus things that a child can do with them. "
That part you got right!
In <81685886-6c51-405d-ada2-9a0f3595c...@m17g2000prl.googlegroups.com>,
Bill Sloman wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
SNIP to this point
One particularly cute application which passed through here a while
back was with someone who was looking to drive an audio transducer at
a higher level than could be afforded by a single transistor doing
Morse "H" forever, and someone suggested using a couple of 555's with
their totem poles arranged as a full bridge, thereby driving the
transducer with about about four times the power available from the
single transistor, at the same supply voltage.
I remember that he posted back, not quite awestruck, but certainly
quite impressed with the performance increase he enjoyed from his
transducer for certainly less than a dollar's worth of parts.
Another of the 101 things a boy can do with a 555.
A low cost 8-pin IC that can be used as an inverting buffer and that
can drive some dynamic loudspeakers can get a market by making very low
cost somewhat loud things that buzz or beep. Add a mere 4 capacitors
for "best practice", can often get away with 2, and if the transducer is a
piezo one fewer still, plus only one resistor.
Some of the things that boys and girls can do with a 555 can get a
market. My father told me that engineering is an economic science.
He even told me that it is not worth spending more than $999 on a pumpkin
cannon in a pumpkin cannon contest whose 1st prize is $1K, unless the
winning position has value beyond the prize payout.
----
And you can do what?
About three?
----
Only if I washed my hands afterwards.
I think that says something!!!
(Not that I usually agree with JF, who I find/"find" to often show mean
spirit.)
I doubt if this was
the only way of solving that poster's problem, and I'd be surprised if
it was the minimum solution, but since you haven't specified the
problem solved in any detail, this is pure speculation.
---
SNIP a bit of digression
There's enough detail there for someone skilled in the art to be able
to flesh out a solution.
We don't even have the rail voltage.
Most microprocessors simpler than a Pentium need voltages that a 555
can work from. So do most logic IC families.
If the supply voltage is a low one like 3.3 volts or less, then getting
a lot of sound from an audio transducer is likely to require a buffer,
voltage boost such as with a transformer (likely requiring a buffer after
digital type stuff), or trickery that gets harder to do if the
transducer's package has to be miniaturized, especially if the transducer
is a cheap one.
In such low voltage cases, I would try out a 556 and a 40106, and in
either case I feel like I am mildly abusing them. There is also the LM386
as a nice cheap 8-pin low-parts-count audio amplifier, somewhat optimized
towards lowish supply voltages like as low as 6 volts, works not much
worse at 4.5-5.
" Bottom line, I like 555s because their cost is low, they are quick and
simple to implement, and they are *reliable* at doing many of the 101-
plus things that a child can do with them. "
That part you got right!
Quote:
Plus 555s are easy and cheap to obtain if the circuit fails. It's easy
to find a new 555, hard to find some custom programmed logic chip. I
like making things that can be easily fixed if they break.
to find a new 555, hard to find some custom programmed logic chip. I
like making things that can be easily fixed if they break.
I would agree with that, but with qualification. If I break something
by being a klutz due to working on something past 2 AM or rushing a
prototype that is running late for a trade show, I accept that I like
easily-replaceable components.
In a trade show rush however, component cost matters little. Getting
a prototype to work for the show is worth a few orders of magnitude more.
But once something that showed well at a trade show goes into
production, what matters on products that I work on is performance,
reliability and low cost.
Favoring reliability favors at least some usage of legacy workhorses
that have a good track record of doing well until they are unable to
compete on such basis. Favoring lower cost favors at least some usage
of circuit designs and components that the designer is already familiar
with, so as to reduce time wasted to learn how to use something newer that
achieves only slight improvement.
One more consideration - cost of producing a product, including cost
of developing it? If the product is developed in expectation of annual
sales in the millions, higher development costs including higher
development team payroll is more allowable to squeeze out 1/100's of
pennies here and there in per-unit production cost, as well as
more-optimized PCB layout to minimize whatever such as RFI or to make
a power transistor run a couple degrees cooler.
But if the project is expecting annual sales in the thousands to 10's of
thousands and faces major competetion in part from price even in a niche
market, its development needs to be done on a budget. Profit is achieved
there by doing a fair amount of "quick-and-whatever" working with what
has good track records, including "devils that the designer knows" as
opposed to ones that need to be learned.
Quote:
-Bill
what I said>
--
- Don Klipstein (don_at_misty.com)
Don Klipstein
Guest
Guest
Wed Sep 01, 2010 8:30 am
In <9f8a65c2-79cf-4429-bc4f-e115f9a59575_at_q40g2000prg.googlegroups.com>,
Bill Sloman wrote:
Quote:
On Sep 1, 9:18 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Not that I even think of a 555 as a monostable, based on how I have
seen that thing described.
Furthermore, I have used 555s for purposes not involving comparator
of a ramp to a more-steady voltage.
Further-furthermore, why should a 555 be worse than alternatives for
usage of a ramp signal? How is a 555 worse than a 40106 as a Schmidt
trigger inverting buffer, other than having 1 rather than 6 of such?
Quote:
If you've got a money making idea that requires
nothing more than a 555, would you reject it because it contains
a monostable? Would you insist on something other than the 555?
No, but the chance that a 555 would be the best solution is pretty
low, while the chance that some clueless amateur would think that the
555 was the best solution is relatively high.
nothing more than a 555, would you reject it because it contains
a monostable? Would you insist on something other than the 555?
No, but the chance that a 555 would be the best solution is pretty
low, while the chance that some clueless amateur would think that the
555 was the best solution is relatively high.
As I have recently posted, I beg to differ. Especially for lower
development cost in some cases and production costs in a few more,
especially if designed by "old farts" that make use of time-tested
workhorses that are the "devils that the designers know".
"Learning new devils" is extra cost. Often, the budget there is
limited. To significant opportunistic extent, bids to make money are
won by showing low cost of components plus cost of development.
There are ones that make money with electronics design with time-tested
workhorses (both specific components / type-of-componets, and circuit
designs that use such) that cost little to recycle.
I do that to get nickels rolling in, millions of them so far despite
having a non-electronics "day job". After-taxes left me enough to own
and operate and pay insurance on automobiles ever since I learned to
drive one at the ripe old age that I had 14 years ago about twice the
age allowed my way to sign full-blast contracts and drive motor vehicles
on highways without parental sign-off.
Can you achieve a profitable business getting even 1 case of beer
annually by eschewing the 555 from the kiddies that make use of it, or
anywhere elsehow with electronics?
Oh, how about making some profit from a fun hobby? That has at least
a bit of requirement to compete against whatever-others, such as the
ones that I know in my electronics "side job". Even if that is
improvement in bicycle headlights that outspread only a little, and LED
work lights that in recent years ???maybe???-guesstimating achieved
goodly-profitable worldwide sales in recent years getting into the 10,000s
annually. (Professional automotive tools, as opposed to a cheaper thing
that Sears or Home Depot or Lowes sells, and at this moment I am in a good
mood to compete against those with "legacy components" except that my time
is limited and I use it where it suits me well, in fair part financially.
Quote:
--
Bill Sloman, Nijmegen
Bill Sloman, Nijmegen
--
- Don Klipstein (don_at_misty.com)
John Fields
Guest
Guest
Wed Sep 01, 2010 1:33 pm
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
<bill.sloman_at_ieee.org> wrote:
Quote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
Make something work with one implementation or another of one or two
555s and lack of a microprocessor, and it generally costs less than using
a microprocessor. Much of the time, the story is the same if the
alternative to the 555 is an op-amp or basic logic ICs. 555s are also
smaller and have fewer pins than logic ICs generally have, and it's my
favorite Schmidt trigger inverting buffer when I only need one rather
than 2-6. It even has a wider and more predictable hysteresis range than
the 40106.
---
Yup, I'd be willing to bet that Dr. Camenzind is flabbergasted, and
immensely pleased, with the ways his baby has been put to work.
If you'd read his book - which you can now download for free
http://www.designinganalogchips.com/
you know that chapter 11 discusses the 555 in detail, and how the
circuit could be improved. He's certainly proud of the design, but
he's - tellingly - particularly proud of being able to fit it into an
8-pin package, which was the primary contributor to its commercial
success.
---
Your point being???
---
Hans Camenzind's attitude to the 555 is a matter of public record. In
his book he doesn't admit to being either "flabbergasted" or
"immensely pleased". We've discussed his book here earlier, and you
should know better than to parade your guesses as to what he he might
think about the design when you should have found out what he actually
thought back when he wrote the book.
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
Make something work with one implementation or another of one or two
555s and lack of a microprocessor, and it generally costs less than using
a microprocessor. Much of the time, the story is the same if the
alternative to the 555 is an op-amp or basic logic ICs. 555s are also
smaller and have fewer pins than logic ICs generally have, and it's my
favorite Schmidt trigger inverting buffer when I only need one rather
than 2-6. It even has a wider and more predictable hysteresis range than
the 40106.
---
Yup, I'd be willing to bet that Dr. Camenzind is flabbergasted, and
immensely pleased, with the ways his baby has been put to work.
If you'd read his book - which you can now download for free
http://www.designinganalogchips.com/
you know that chapter 11 discusses the 555 in detail, and how the
circuit could be improved. He's certainly proud of the design, but
he's - tellingly - particularly proud of being able to fit it into an
8-pin package, which was the primary contributor to its commercial
success.
---
Your point being???
---
Hans Camenzind's attitude to the 555 is a matter of public record. In
his book he doesn't admit to being either "flabbergasted" or
"immensely pleased". We've discussed his book here earlier, and you
should know better than to parade your guesses as to what he he might
think about the design when you should have found out what he actually
thought back when he wrote the book.
---
Even though you continually pat yourself on the back for being
competent in the use of the English language, it seems reading
comprehension has tripped you up again in that I said: "I'd be
willing to bet that Dr. Camenzind is flabbergasted, and immensely
pleased, with the ways his baby has been put to work."
Notice that I used the present tense, indicating that I was talking
about now, not then.
In any case, from page 11-3:
"The market reaction to the 555 timer was truly amazing. Art Fury
made history by bringing out the circuit at an unprecedented low
price, 75 cents. I had deliberately made the design flexible, but nine
out of ten applications were in areas and ways I had never
contemplated. For months I was inundated by phone calls from engineers
who had a new idea for using the timer. To this day the 555 has been
the best-selling IC every year, copied by numerous companies. Except
for a CMOS version, the design has never been changed."
Notice the use of phrases like "truly amazing", "ways I had never
contemplated", "inundated by phone calls", and arguably the most
interesting: "To this day the 555 has been the best-selling IC every
year, copied by numerous companies.", which must certainly gall you.
The point here is that even though he doesn't state it explicitly, his
feelings were certainly those which accompany being flabbergasted,:
http://www.merriam-webster.com/dictionary/flabbergasted
So I'd be willing to bet that if were to be asked if he was
flabbergasted back then, his answer would certainly be in the
affirmative.
As for being immensely pleased, one would have to be rather thick to
presume he wouldn't be.
Oh, wait...
---
Quote:
One particularly cute application which passed through here a while
back was with someone who was looking to drive an audio transducer at
a higher level than could be afforded by a single transistor doing
Morse "H" forever, and someone suggested using a couple of 555's with
their totem poles arranged as a full bridge, thereby driving the
transducer with about about four times the power available from the
single transistor, at the same supply voltage.
I remember that he posted back, not quite awestruck, but certainly
quite impressed with the performance increase he enjoyed from his
transducer for certainly less than a dollar's worth of parts.
Another of the 101 things a boy can do with a 555.
---
And you can do what?
About three?
---
Only if I washed my hands afterwards.
back was with someone who was looking to drive an audio transducer at
a higher level than could be afforded by a single transistor doing
Morse "H" forever, and someone suggested using a couple of 555's with
their totem poles arranged as a full bridge, thereby driving the
transducer with about about four times the power available from the
single transistor, at the same supply voltage.
I remember that he posted back, not quite awestruck, but certainly
quite impressed with the performance increase he enjoyed from his
transducer for certainly less than a dollar's worth of parts.
Another of the 101 things a boy can do with a 555.
---
And you can do what?
About three?
---
Only if I washed my hands afterwards.
---
If you were working for me I'd require you to wash your hands _before_
you touched anything in the lab.
---
Quote:
I doubt if this was
the only way of solving that poster's problem, and I'd be surprised if
it was the minimum solution, but since you haven't specified the
problem solved in any detail, this is pure speculation.
---
... "it is a tale
Told by an idiot, full of sound and fury,
Signifying nothing."
As is about 90% of what you write.
Since you clearly don't understand 90% of what I post, it won't
signify much to you. A tale told to an idiot who doesn't appreciate
what it might have signified to a better informed audience.
the only way of solving that poster's problem, and I'd be surprised if
it was the minimum solution, but since you haven't specified the
problem solved in any detail, this is pure speculation.
---
... "it is a tale
Told by an idiot, full of sound and fury,
Signifying nothing."
As is about 90% of what you write.
Since you clearly don't understand 90% of what I post, it won't
signify much to you. A tale told to an idiot who doesn't appreciate
what it might have signified to a better informed audience.
---
Oh, yes, Bill, I understand.
You're a really gifted author and a genius who can write between the
lines and convey all sorts of hidden meanings to those who can't
understand them.
Seems kind of silly to me, if what you're trying to do is communicate.
Of course the possibility also exists that you're a marginally
competent writer with a huge ego who can't quite get what he wants to
say on paper, but expects everyone to magically translate chicken
scratches into parables.
I think I'll go for the latter.
---
Quote:
There's enough detail there for someone skilled in the art to be able
to flesh out a solution.
We don't even have the rail voltage.
to flesh out a solution.
We don't even have the rail voltage.
---
Why do you need it?
You should be able to come up with a design without it, and then work
it in later, but if you can't quite wrap your mind around that, think:
"Hmm... 555, V+, lemme go get the data sheet..."
---
Quote:
Of course that puts you at a disadvantage, so your only recourse is to
malign, instead of showing your minimalist "solution".
---
IIRR the 555's totem pole output doesn't get all that close to the
positive rail, so "four times the power available" may be something of
an exaggeration.
---
How so?
If the single transistor driving the load was a single 555's totem
pole emitter follower, then using two 555's in a full bridge, with the
same drop in each emitter follower, would result in about four times
the power dissipated in the load than in the case with a single 555.
Besides, what is it you don't understand about "about"?
With a single 555, the load can be returned directly to the postive
rail, and will see the rail voltage minus the saturation voltage of
the output - about 0.1V at 5mA.
malign, instead of showing your minimalist "solution".
---
IIRR the 555's totem pole output doesn't get all that close to the
positive rail, so "four times the power available" may be something of
an exaggeration.
---
How so?
If the single transistor driving the load was a single 555's totem
pole emitter follower, then using two 555's in a full bridge, with the
same drop in each emitter follower, would result in about four times
the power dissipated in the load than in the case with a single 555.
Besides, what is it you don't understand about "about"?
With a single 555, the load can be returned directly to the postive
rail, and will see the rail voltage minus the saturation voltage of
the output - about 0.1V at 5mA.
---
Of course it can, but that's moving the goalpost since I specified
that if a single emitter follower was used to drive the load, then a
full bridge used to drive the load would deliver about 4 times more
power into the load than the half-bridge.
---
Quote:
With your "H" bridge, the load has to be connected between two totem
pole output stages. The low side will still be only about 0.1V above
the negative rail, but the high side will be around 1.4V below the
positive rail. With a 5V rail, you would not put four times as much
power into the load as the single-ended driver but only about twice as
much.
pole output stages. The low side will still be only about 0.1V above
the negative rail, but the high side will be around 1.4V below the
positive rail. With a 5V rail, you would not put four times as much
power into the load as the single-ended driver but only about twice as
much.
---
True, but irrelevant since the comparison I was making was between the
upper emitter follower and the full bridge, not between the lower
common emitter and the full bridge.
---
Quote:
http://focus.ti.com/lit/ds/symlink/ne555.pdf
And "about" implies variation above and below an estimate.
---
In the context in which it was used, "about" means "approximately", as
you well know, so why are you being such a horse's ass about it?
Grasping at straws, I suspect.
---
Quote:
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Here:
Since there's no entry on TI's data sheet where Iol = Ioh for Vcc =
5v, let's use equal source and sink currents for which Vcc is
specified, OK?
With that in mind, we find that with Vcc = 15V and Iol = Ioh = 100mA,
we have Voh = 13.3V typ and Vol = 2V typ.
Looking at the full-bridge first:
+15 +15
| |
C C
ON B B OFF
E E
E1 | R1 | E2
13.3V---+--[110R]--+---2V
| I |
C 100mA-> C
OFF B B ON
E E
| |
GND GND
The value of the resistance is, of course:
E1 - E2 11.3V
R1 = --------- = ------- = 113 ohms
I 0.1A
110 ohms is a standard 5% value and the lower resistance will allow
about 103mA through the bridge and the resistor, which won't hurt
anything, and with 11.3 volts across the resistor it'll dissipate 1.16
watts.
Now the common emitter:
+15
|
|
|
|
E1 | R1 E2
15V---+--[130R]--+--2V
I |
100mA-> C
B ON
E
|
GND
In this case we have 13V across R1, so for 100mA through it it would
need to be 130 ohms, as shown, and it would dissipate 1.3 watts.
Assuming that R1 is the transducer and has a fixed impedance means
that in the bridge instance it'll be 130 ohms as well and, with 11.3V
across it will dissipate 982 milliwatts, about 25% less than using the
common emitter.
Now, assuming a 50% duty cycle for the common emitter means that
there'll be current through R1 only half the time, so R1 will be
dissipating an average power of 650 milliwatts.
The bridge, however, will force current through R1 all the time, first
in one direction and then the other.
At first glance it might seem that the bridge, under ideal conditions,
could allow 4 times 982 milliwatts to be dissipated by R1, but such
isn't the case.
Consider:
With 11.3V across R1 (130 ohms) and 87mA moving from left to right,
say, R1 will be dissipating 982 milliwatts.
If the direction of the current changes to from right to left, as it
will during the next half cycle of the brige's operation, there'll
still be 11.3V across, and 87mA through R1, so it'll still be
dissipating 982 milliwatts.
Its average dissipation, then, will be 982 milliwatts, while that of
the common emitter will be 650 milliwatts.
Let's take it one step farther and assume that we have perfect
transistors (or MOSFETs), and that we use complementary devices in the
bridge so we can get the entire supply across the load.
Then our bridge would look like this:
+15 +15
| |
D D
ON G NCH NCH G OFF
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S
OFF G PCH PCH G ON
D D
| |
GND GND
And, regardless of the direction of current through R1, R1 would be
dissipating:
E² 225
P = --- = ------ = 1.5 watts,
R 150R
all the time.
Since we have perfect switches, your common emitter example is
equivalent to:
+15 +15
| |
D D
ON G NCH NCH G---GND
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S __
+15---G PCH PCH G ON
D D
| |
GND GND
where the timing looks like this:
____ ____ ____
ON ___| |____| |____| |____
__ ___ ____ ____ ____
ON |____| |____| |____|
Since nothing has changed in terms of the supply and the switch
resistances, R1 still dissipates 1.5 watts when the switches are on,
but since they're only on half the time, R1 dissipates an average
power of 0.75 watts.
Finally, since we have perfect components, the advantage of the bridge
over the single-ended example is:
P1 1.5W
n = ---- = ------- = 2
P2 0.75W
So it's clear to see that in the real world, with imperfect
components, the advantage can only approach 2, not 4.
Next, I'll address your erroneous "infinite supply" conjecture, but in
another post.
This one is complete; enjoy. :-)
---
JF
John Fields
Guest
Guest
Wed Sep 01, 2010 7:10 pm
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
<bill.sloman_at_ieee.org> wrote:
..
..
..
Quote:
With a single 555, the load can be returned directly to the postive
rail, and will see the rail voltage minus the saturation voltage of
the output - about 0.1V at 5mA.
With your "H" bridge, the load has to be connected between two totem
pole output stages. The low side will still be only about 0.1V above
the negative rail, but the high side will be around 1.4V below the
positive rail. With a 5V rail, you would not put four times as much
power into the load as the single-ended driver but only about twice as
much.
http://focus.ti.com/lit/ds/symlink/ne555.pdf
And "about" implies variation above and below an estimate. Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
rail, and will see the rail voltage minus the saturation voltage of
the output - about 0.1V at 5mA.
With your "H" bridge, the load has to be connected between two totem
pole output stages. The low side will still be only about 0.1V above
the negative rail, but the high side will be around 1.4V below the
positive rail. With a 5V rail, you would not put four times as much
power into the load as the single-ended driver but only about twice as
much.
http://focus.ti.com/lit/ds/symlink/ne555.pdf
And "about" implies variation above and below an estimate. Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Consider a resistive load being driven by an N-channel MOSFET
common-source switch:
+15V E1
|
[150R] R1
|
D Q1
CLK>---G Nch
S
|
GND
With CLK being a square wave capable of fully enhancing and fully
depleting Q1, the average power dissipated by R1 will be:
E1² 225
P = ----- = ------ = 0.75 watt
2R1 300R
Modifying the circuit so that it becomes a half-bridge and adding a
negative supply gives us:
+15V E1
|
D Q1
CLK>---G Nch
S
| R1
+--[150]--GND
|
___ S
CLK>---G Pch
D
|
-15V E2
where for complementary square-wave drive and symmetrical supplies,
the average power dissipated by R1 will be:
E1²
P = ---- = 1.5 watts.
R1
Now, in the case of a full bridge:
+15V E1
|
+------+------+
| |
D Q1 D ___
CLK>---G Nch Nch G---CLK
S S
| R1 |
+----[150]----+
| |
S S ___
CLK>---G Pch Pch G---CLK
D D
| |
+------+------+
|
-15V E2
the power dissipted by R1 will be:
(E1 + E2)² 900
P = ----------- = ------ = 6 watts,
R1 150R
which is four times the power available from the half-bridge and 8
times the power available from the simple common-source switch using,
instead of a horribly expensive infinite-voltage power supply, two
simple 15V sources.
---
JF
oparr@hotmail.com
Guest
Guest
Wed Sep 01, 2010 9:40 pm
On Aug 23, 3:22 pm, "amdx" <a...@knology.net> wrote:
Quote:
Last post I see from Phil was 6/17.
Any idea where he is?
Any idea where he is?
The malignant spirit is now possessing Archie according to my exorcist
tracker thingy.
Bill Sloman
Guest
Guest
Thu Sep 02, 2010 5:58 am
On Sep 1, 3:30 pm, d...@manx.misty.com (Don Klipstein) wrote:
Quote:
In <9f8a65c2-79cf-4429-bc4f-e115f9a59...@q40g2000prg.googlegroups.com>,
Bill Sloman wrote:
On Sep 1, 9:18 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch..
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Not that I even think of a 555 as a monostable, based on how I have
seen that thing described.
Furthermore, I have used 555s for purposes not involving comparator
of a ramp to a more-steady voltage.
Further-furthermore, why should a 555 be worse than alternatives for
usage of a ramp signal?
Bill Sloman wrote:
On Sep 1, 9:18 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch..
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Not that I even think of a 555 as a monostable, based on how I have
seen that thing described.
Furthermore, I have used 555s for purposes not involving comparator
of a ramp to a more-steady voltage.
Further-furthermore, why should a 555 be worse than alternatives for
usage of a ramp signal?
I never said that it was. Anything that relies on a slow ramp
approaching a threshold has the same problem.
Quote:
How is a 555 worse than a 40106 as a Schmidt
trigger inverting buffer, other than having 1 rather than 6 of such?
trigger inverting buffer, other than having 1 rather than 6 of such?
Who cares?
Quote:
If you've got a money making idea that requires
nothing more than a 555, would you reject it because it contains
a monostable? Would you insist on something other than the 555?
No, but the chance that a 555 would be the best solution is pretty
low, while the chance that some clueless amateur would think that the
555 was the best solution is relatively high.
As I have recently posted, I beg to differ. Especially for lower
development cost in some cases and production costs in a few more,
especially if designed by "old farts" that make use of time-tested
workhorses that are the "devils that the designers know".
"Learning new devils" is extra cost.
nothing more than a 555, would you reject it because it contains
a monostable? Would you insist on something other than the 555?
No, but the chance that a 555 would be the best solution is pretty
low, while the chance that some clueless amateur would think that the
555 was the best solution is relatively high.
As I have recently posted, I beg to differ. Especially for lower
development cost in some cases and production costs in a few more,
especially if designed by "old farts" that make use of time-tested
workhorses that are the "devils that the designers know".
"Learning new devils" is extra cost.
But one that no serious designer of electronics can avoid. I spent
roughly thirty years keeping a eye out for new devices, and every now
and then one would look as if it offered a better way of solving a
problem than the solution I'd found earlier.
Quote:
Often, the budget there is limited. To significant opportunistic extent, bids to make money are won by showing low cost of components plus cost of development.
But if there is a better/cheaper component that you don't know about,
your bid is dead in the water.
Quote:
There are ones that make money with electronics design with time-tested
workhorses (both specific components / type-of-componets, and circuit
designs that use such) that cost little to recycle.
I do that to get nickels rolling in, millions of them so far despite
having a non-electronics "day job".
workhorses (both specific components / type-of-componets, and circuit
designs that use such) that cost little to recycle.
I do that to get nickels rolling in, millions of them so far despite
having a non-electronics "day job".
If electronics was your day job, you'd be exposed to a much wider
range of components, and might be able to get a bit closer to the
state of the art.
Quote:
After-taxes left me enough to own
and operate and pay insurance on automobiles ever since I learned to
drive one at the ripe old age that I had 14 years ago about twice the
age allowed my way to sign full-blast contracts and drive motor vehicles
on highways without parental sign-off.
Can you achieve a profitable business getting even 1 case of beer
annually by eschewing the 555 from the kiddies that make use of it, or
anywhere elsehow with electronics?
and operate and pay insurance on automobiles ever since I learned to
drive one at the ripe old age that I had 14 years ago about twice the
age allowed my way to sign full-blast contracts and drive motor vehicles
on highways without parental sign-off.
Can you achieve a profitable business getting even 1 case of beer
annually by eschewing the 555 from the kiddies that make use of it, or
anywhere elsehow with electronics?
Not in the Netherlands.
Quote:
Oh, how about making some profit from a fun hobby? That has at least
a bit of requirement to compete against whatever-others, such as the
ones that I know in my electronics "side job". Even if that is
improvement in bicycle headlights that outspread only a little, and LED
work lights that in recent years ???maybe???-guesstimating achieved
goodly-profitable worldwide sales in recent years getting into the 10,000s
annually. (Professional automotive tools, as opposed to a cheaper thing
that Sears or Home Depot or Lowes sells, and at this moment I am in a good
mood to compete against those with "legacy components" except that my time
is limited and I use it where it suits me well, in fair part financially.
a bit of requirement to compete against whatever-others, such as the
ones that I know in my electronics "side job". Even if that is
improvement in bicycle headlights that outspread only a little, and LED
work lights that in recent years ???maybe???-guesstimating achieved
goodly-profitable worldwide sales in recent years getting into the 10,000s
annually. (Professional automotive tools, as opposed to a cheaper thing
that Sears or Home Depot or Lowes sells, and at this moment I am in a good
mood to compete against those with "legacy components" except that my time
is limited and I use it where it suits me well, in fair part financially.
Whatever works for you. I wouldn't have clue what that particular
market wanted, and even less of clue how to find people who might be
willing to sell something that I'd developed into that market.
And I don't seem to get excited about circuits that don't fit into
something that could be broadly described as a scientific instrument,
probably because that is the context in which I've worked since about
1965.
--
Bill Sloman, Nijmegen
Bill Sloman
Guest
Guest
Thu Sep 02, 2010 7:26 am
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
Quote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
<snip>
Quote:
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted. The power being dissipated in the transducer would - as
you say - only be doubled, but it isn't a parameter of any particular
interest, unless it gets it hot enough to burn it out.
I did notice this when I was doing my little bit of number crunching,
but ressolved the apparent contradiction by reminding myself that the
transducer was effectively AC-coupled to the OP's ear.
--
Bill Sloman, Nijmegen
John Fields
Guest
Guest
Thu Sep 02, 2010 1:32 pm
On Wed, 01 Sep 2010 07:33:37 -0500, John Fields
<jfields_at_austininstruments.com> wrote:
Quote:
Let's take it one step farther and assume that we have perfect
transistors (or MOSFETs), and that we use complementary devices in the
bridge so we can get the entire supply across the load.
Then our bridge would look like this:
+15 +15
| |
D D
ON G NCH NCH G OFF
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S
OFF G PCH PCH G ON
D D
| |
GND GND
And, regardless of the direction of current through R1, R1 would be
dissipating:
E² 225
P = --- = ------ = 1.5 watts,
R 150R
all the time.
Since we have perfect switches, your common emitter example is
equivalent to:
+15 +15
| |
D D
ON G NCH NCH G---GND
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S __
+15---G PCH PCH G ON
D D
| |
GND GND
where the timing looks like this:
____ ____ ____
ON ___| |____| |____| |____
__ ___ ____ ____ ____
ON |____| |____| |____|
Since nothing has changed in terms of the supply and the switch
resistances, R1 still dissipates 1.5 watts when the switches are on,
but since they're only on half the time, R1 dissipates an average
power of 0.75 watts.
Finally, since we have perfect components, the advantage of the bridge
over the single-ended example is:
P1 1.5W
n = ---- = ------- = 2
P2 0.75W
So it's clear to see that in the real world, with imperfect
components, the advantage can only approach 2, not 4.
Next, I'll address your erroneous "infinite supply" conjecture, but in
another post.
This one is complete; enjoy.
transistors (or MOSFETs), and that we use complementary devices in the
bridge so we can get the entire supply across the load.
Then our bridge would look like this:
+15 +15
| |
D D
ON G NCH NCH G OFF
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S
OFF G PCH PCH G ON
D D
| |
GND GND
And, regardless of the direction of current through R1, R1 would be
dissipating:
E² 225
P = --- = ------ = 1.5 watts,
R 150R
all the time.
Since we have perfect switches, your common emitter example is
equivalent to:
+15 +15
| |
D D
ON G NCH NCH G---GND
S S
E1 | R1 | E2
15V---+--[150R]--+---0V
| I |
S 100mA-> S __
+15---G PCH PCH G ON
D D
| |
GND GND
where the timing looks like this:
____ ____ ____
ON ___| |____| |____| |____
__ ___ ____ ____ ____
ON |____| |____| |____|
Since nothing has changed in terms of the supply and the switch
resistances, R1 still dissipates 1.5 watts when the switches are on,
but since they're only on half the time, R1 dissipates an average
power of 0.75 watts.
Finally, since we have perfect components, the advantage of the bridge
over the single-ended example is:
P1 1.5W
n = ---- = ------- = 2
P2 0.75W
So it's clear to see that in the real world, with imperfect
components, the advantage can only approach 2, not 4.
Next, I'll address your erroneous "infinite supply" conjecture, but in
another post.
This one is complete; enjoy.
---
Ooops...
The P channels should be on top, the N channels on the bottom, and the
drive signals adjusted accordingly:
+15 +15
| |
S S
A>--G PCH PCH G--<B
D D
| R1 |
+----[150R]----+
| I |
D <-100mA-> D
A>--G NCH NCH G--<B
S S
| |
GND GND
____ ____ ___
A ___| |____| |____|
___ ____ ____
B |____| |____| |___
---
JF
John Fields
Guest
Guest
Thu Sep 02, 2010 3:08 pm
On Wed, 1 Sep 2010 21:26:32 -0700 (PDT), Bill Sloman
<bill.sloman_at_ieee.org> wrote:
Quote:
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
---
Yes, I'd forgotten that.
But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.
Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.
All in all, I think the point has been made that 555's are extremely
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.
---
JF
ehsjr
Guest
Guest
Thu Sep 02, 2010 6:41 pm
Bill Sloman wrote:
Quote:
On Sep 1, 9:18 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
BillSlomanwrote:
snip
That is the wording that that you would have preferred that I used.
Everybody's opinion of the reliability of their knowledge is
fundamentally subjective, but my data-base has been being tested
against reality for some fifty years now, and has proved to be pretty
reliable.
You seem to have stopped testing yours against reality around the time
the 555 became obsolescent, which would be about thirty years ago.
Hmmm. A search in Mouser for the 555 yields 6 pages. On the
first page alone you'll find that there are 152,667 555s in
stock. Searching for 555s in Digikey yields 4 pages of results,
all in stock. The quantity on the first page alone totally
swamps the Mouser quantities - well over 400,000 in stock.
Mouser and Digikey (and others) seem to have a better grip on
reality than you do, focusing on the viability of the part,
rather than what you see as its "obsolence".
The 555 is a legacy part - like the the 741 - and still sells in large
numbers. When the 555 was introduced it did provide a compact and
adequate solution to a commonly encountered problem, and was designed
into a lot of products. Some of these are still in production.
As with all frequently used parts, it is still beoing incoprporated
into new designs. Hobbyists and amateurs copy old designs, because
they know - or at least fondly believe - that they work, and don't
know enough to design anything better.
Some professional designers - like John Fields - who should know
better, still design around legacy parts, because it lets them recycle
old designs which they know to be reliable. If you are designing
something in a hurry, or don't want to risk designing something that
you can't be sure will work out of the box, using familiar - if
obsolete - parts can be a good short term strategy.
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
--
Bill Sloman, Nijmegen
Thank you for giving a reasoned reply. I would like to ask about one
part of it: "The catch with the 555 is that it combines a part nobody
really ought to use these days - a monostable - with a rather poor
quality bipolar power transistor, and uses the same ground return pin
for both devices."
I do not understand why you make a blanket statement indicating
that one should not use a monostable. If a monostable does the
job, why use something else?
Monostgables depend on comparing a slow ramp with a reference voltage,
and consequently tend to be messed up by electrical noise.
I've used lots of them, so I'm well aware of this weakness.
Ok, but that doesn't answer the question. If it does the job,
whatever weakness the monostable it has is irrelevant. However,
I think I found the answer in your reply to Don. Your interest
is in scientific instrumentation, so the noise would preclude
that chip for you.
Quote:
If you've got a money making idea that requires
nothing more than a 555, would you reject it because it contains
a monostable? Would you insist on something other than the 555?
No, but the chance that a 555 would be the best solution is pretty
low, while the chance that some clueless amateur would think that the
555 was the best solution is relatively high.
Well, you're not qualified to say that, until you consider the
market and the product. I think you look at this from a different
frame of reference, based on your experience in the scientific
instrumentation over the years. "Best" does not necessarily mean
technologically superior. The vast majority of consumers do
not use scientific instrumentation. "Best" includes financial
as well as technological consideration. The "best" dsp is
not required for a cheap radio. The "best" _______ (fill in
the blank) is *most* often not a requirement.
The fact is, wherever "best" fits into the discussion in your
view, that the 555 is hugely viable commercially, no where
near obsolete.
Anyway, I think I understand your point of view, and it seems
too narrow to be valid as applied in general. And, it is also
specious to conclude that a designer is a clueless amateur
because he/she chooses a 555 for an application.
Ed
Quote:
--
Bill Sloman, Nijmegen
Charlie E.
Guest
Guest
Fri Sep 03, 2010 6:13 pm
On Mon, 30 Aug 2010 21:26:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Quote:
Bill Sloman wrote:
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
I did about 15 years ago. For a small signal conditioner/logic
analysis project. Goal was to combine the output from 12 different
laser sensors (2 channels per sensor) into five different outputs.
Used a 556 to get two different clocks, one about 1KHz, and the other
about 200 Hz. They clocked some Moto debounce chips to clean up the
signals, and to provide a fixed delay. Design also used several
EPROMs as async combinatorial logic...
Charlie
Phil Hobbs
Guest
Guest
Fri Sep 03, 2010 6:30 pm
Charlie E. wrote:
Quote:
On Mon, 30 Aug 2010 21:26:42 -0400, Phil Hobbs
pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Bill Sloman wrote:
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
I did about 15 years ago. For a small signal conditioner/logic
analysis project. Goal was to combine the output from 12 different
laser sensors (2 channels per sensor) into five different outputs.
Used a 556 to get two different clocks, one about 1KHz, and the other
about 200 Hz. They clocked some Moto debounce chips to clean up the
signals, and to provide a fixed delay. Design also used several
EPROMs as async combinatorial logic...
Charlie
pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Bill Sloman wrote:
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
I did about 15 years ago. For a small signal conditioner/logic
analysis project. Goal was to combine the output from 12 different
laser sensors (2 channels per sensor) into five different outputs.
Used a 556 to get two different clocks, one about 1KHz, and the other
about 200 Hz. They clocked some Moto debounce chips to clean up the
signals, and to provide a fixed delay. Design also used several
EPROMs as async combinatorial logic...
Charlie
I've never used an asynchronous EPROM that way. IIRC I first heard
about it in the "CMOS Cookbook", before PALs existed. Back then I also
used data-selector logic, where I with a CD4067 1<->16 analogue MUX, I
could get any logical combination of (gasp) _5_ inputs with a single chip!
That actually allowed me to simplify the hot-swap logic in the first
civilian bidirectional direct-broadcast satellite system (Spacetel from
AEL Microtel) which was introduced at the end of 1983 or early 1984.
Every central-office board had to have that logic, but they didn't think
to standardize it, so everybody just rolled their own. My boards were
the first to be released to manufacturing, and I had circulated my
design in an internal memo way in advance. Of course, since I was a
22-year-old new hire at the time, nobody listened AFAIK. Some of those
designs were real rococo stuff.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
Charlie E.
Guest
Guest
Fri Sep 03, 2010 6:45 pm
On Fri, 03 Sep 2010 13:30:09 -0400, Phil Hobbs
<pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Quote:
Charlie E. wrote:
On Mon, 30 Aug 2010 21:26:42 -0400, Phil Hobbs
pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Bill Sloman wrote:
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
I did about 15 years ago. For a small signal conditioner/logic
analysis project. Goal was to combine the output from 12 different
laser sensors (2 channels per sensor) into five different outputs.
Used a 556 to get two different clocks, one about 1KHz, and the other
about 200 Hz. They clocked some Moto debounce chips to clean up the
signals, and to provide a fixed delay. Design also used several
EPROMs as async combinatorial logic...
Charlie
I've never used an asynchronous EPROM that way. IIRC I first heard
about it in the "CMOS Cookbook", before PALs existed. Back then I also
used data-selector logic, where I with a CD4067 1<->16 analogue MUX, I
could get any logical combination of (gasp) _5_ inputs with a single chip!
That actually allowed me to simplify the hot-swap logic in the first
civilian bidirectional direct-broadcast satellite system (Spacetel from
AEL Microtel) which was introduced at the end of 1983 or early 1984.
Every central-office board had to have that logic, but they didn't think
to standardize it, so everybody just rolled their own. My boards were
the first to be released to manufacturing, and I had circulated my
design in an internal memo way in advance. Of course, since I was a
22-year-old new hire at the time, nobody listened AFAIK. Some of those
designs were real rococo stuff.
Cheers
Phil Hobbs
On Mon, 30 Aug 2010 21:26:42 -0400, Phil Hobbs
pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Bill Sloman wrote:
On Aug 31, 3:23 am, d...@manx.misty.com (Don Klipstein) wrote:
In article <4C7BE0D4.1050...@electrooptical.net>, Phil Hobbs wrote:
Bill Sloman wrote:
On Aug 30, 5:07 am, ehsjr <eh...@nospamverizon.net> wrote:
Bill Sloman wrote:
snip
The catch with the 555 is that it combines a part nobody really ought
to use these days - a monostable - with a rather poor quality bipolar
power transistor, and uses the same ground return pin for both
devices. There are a few situations where these defects aren't
troublesome, but modern designers tend to make their time control
signals in the digital domain, and use then to drive a MOSFET switch.
There's still a place in the world for monostables. As long as you
don't care if the timing is off by a factor of 2 either way, they work
fine. And obsolescent or not, the 555 will very likely still be
available after today's latest magic micro is gone. It also doesn't
need programming support. Monostables are good for pulse stretching,
for instance, where you don't know when the pulse is going to arrive
with respect to the uC clock.
A delay line is better, if the pulse stretching you want fits into a
delay line you can make or buy.
Why? What's the performance gain, in exchange for using a more
expensive, less general, and less common part?
I can't remember ever having designed a 555 into any actual product, but
I've often used them when hacking something together in a die cast box
for lab use. Quick, simple, no problems. Some of those boxes have been
in use for 20 years, off and on, with various modifications along the way.
Cheers
Phil Hobbs
I did about 15 years ago. For a small signal conditioner/logic
analysis project. Goal was to combine the output from 12 different
laser sensors (2 channels per sensor) into five different outputs.
Used a 556 to get two different clocks, one about 1KHz, and the other
about 200 Hz. They clocked some Moto debounce chips to clean up the
signals, and to provide a fixed delay. Design also used several
EPROMs as async combinatorial logic...
Charlie
I've never used an asynchronous EPROM that way. IIRC I first heard
about it in the "CMOS Cookbook", before PALs existed. Back then I also
used data-selector logic, where I with a CD4067 1<->16 analogue MUX, I
could get any logical combination of (gasp) _5_ inputs with a single chip!
That actually allowed me to simplify the hot-swap logic in the first
civilian bidirectional direct-broadcast satellite system (Spacetel from
AEL Microtel) which was introduced at the end of 1983 or early 1984.
Every central-office board had to have that logic, but they didn't think
to standardize it, so everybody just rolled their own. My boards were
the first to be released to manufacturing, and I had circulated my
design in an internal memo way in advance. Of course, since I was a
22-year-old new hire at the time, nobody listened AFAIK. Some of those
designs were real rococo stuff.
Cheers
Phil Hobbs
One of my teachers in digital logic had just 'mentioned' it, in
passing during our combinatorial logic days. I had six weeks to get a
proto done and tested, an EPROM programmer, no PAL programmer, and no
MCU experience, so if you got a nail, use a hammer!
Basically, I needed a separate 2in-2out state machine for each sensor.
EPROMs had 16 bit address and 8 data out, so folded the outputs to 8
of the inputs, and each EPROM could do four sensors, so I needed three
EPROMs. The fun part was creating a BASIC program to calculate all
the values, and output them into a format that the EPROM programmer
would understand...
Charlie
John Fields
Guest
Guest
Sun Sep 05, 2010 1:28 pm
On Sun, 5 Sep 2010 04:18:28 -0700 (PDT), Bill Sloman
<bill.sloman_at_ieee.org> wrote:
Quote:
On Sep 3, 12:08 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 1 Sep 2010 21:26:32 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
---
Yes, I'd forgotten that.
But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.
Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.
One 555 (or any other cheap and nasty astable) and a complementary
pair of MOSFET switches would have got twice the acoustic power from a
5V rail.
On Wed, 1 Sep 2010 21:26:32 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
---
Yes, I'd forgotten that.
But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.
Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.
One 555 (or any other cheap and nasty astable) and a complementary
pair of MOSFET switches would have got twice the acoustic power from a
5V rail.
---
Got a schematic?
---
Quote:
All in all, I think the point has been made that 555's are extremely
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.
You've managed to convince me that you didn't know that the 555's
totem-pole output doesn't pull all the way up to the positive supply
rail.
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.
You've managed to convince me that you didn't know that the 555's
totem-pole output doesn't pull all the way up to the positive supply
rail.
---
Geez, Bill, then from:
news:kabs76pv59h3dlukcsoumo0ghmhfi3kmt6_at_4ax.com
you must have missed this:
"Since there's no entry on TI's data sheet where Iol = Ioh for Vcc =
5v, let's use equal source and sink currents for which Vcc is
specified, OK?
With that in mind, we find that with Vcc = 15V and Iol = Ioh = 100mA,
we have Voh = 13.3V typ and Vol = 2V typ.
Looking at the full-bridge first:
+15 +15
| |
C C
ON B B OFF
E E
E1 | R1 | E2
13.3V---+--[110R]--+---2V
| I |
C 100mA-> C
OFF B B ON
E E
| |
GND GND"
Quote:
Similar sorts of ignorance and idleness mean that there is still
a market for 555 in notionally new designs (which are - in general -
old designs being recycled long past their sell-by date).
a market for 555 in notionally new designs (which are - in general -
old designs being recycled long past their sell-by date).
---
I don't see it that way at all, since it isn't some ignorant lazybones
who can't see past the end of his nose who's going to parlay
cleverness, vigor, and cheap, reliable hardware into a winner product,
it's going to be some gutsy entrepreneur type who refuses to listen to
the naysayers.
---
Quote:
Human stupidity and idleness are going to be with us for a while yet,
---
You make that point quite clear...
---
Quote:
and the 555 is in no danger of losing its market in the meantime.
---
because it, at least, works.
---
Quote:
The 555 is still totally obsolete, and anyone who finds a 555 in
something being touted as a "new design" should be deeply suspicious
of the quality of the design and the designer.
something being touted as a "new design" should be deeply suspicious
of the quality of the design and the designer.
---
"If Billy doesn't like it then there must be something wrong with you
if you play with it." ???
Gimme a break, you doddering old fart.
---
JF
Bill Sloman
Guest
Guest
Sun Sep 05, 2010 2:18 pm
On Sep 3, 12:08 am, John Fields <jfie...@austininstruments.com> wrote:
Quote:
On Wed, 1 Sep 2010 21:26:32 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
---
Yes, I'd forgotten that.
But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.
Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.
bill.slo...@ieee.org> wrote:
On Sep 1, 10:33 pm, John Fields <jfie...@austininstruments.com> wrote:
On Tue, 31 Aug 2010 07:43:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 18:58:11 -0700 (PDT), Bill Sloman
bill.slo...@ieee.org> wrote:
On Aug 31, 9:25 am, John Fields <jfie...@austininstruments.com> wrote:
On Mon, 30 Aug 2010 17:23:13 +0000 (UTC), d...@manx.misty.com (Don
Klipstein) wrote:
snip
Four times
the power is the upper limit to the advantage, available only with an
infinite supply voltage. You could have legitimately claimed an
advantage *approaching* a four-fold increase in power, but that sort
of careful use of language is quite beyond you.
---
Hmmm... Interestingly, it seems like I _did_ made a mistake, but one
which you not only didn't catch, but also actually went along with.
That is, with the configuration given, the bridge can only approach
_twice_ the power available from the common emitter.
Wrong. Your OP was driving the sounder in a Morse code practice rig.
The power he was interested in was that of the acoustic signal being
generated. Doubling the voltage swing across the sounder doubles the
excursion of the diaphragm, and quadruples the acoustic power being
transmitted.
---
Yes, I'd forgotten that.
But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.
Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.
One 555 (or any other cheap and nasty astable) and a complementary
pair of MOSFET switches would have got twice the acoustic power from a
5V rail.
Quote:
All in all, I think the point has been made that 555's are extremely
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.
You've managed to convince me that you didn't know that the 555's
totem-pole output doesn't pull all the way up to the positive supply
rail. Similar sorts of ignorance and idleness mean that there is still
a market for 555 in notionally new designs (which are - in general -
old designs being recycled long past their sell-by date).
Human stupidity and idleness are going to be with us for a while yet,
and the 555 is in no danger of losing its market in the meantime.
The 555 is still totally obsolete, and anyone who finds a 555 in
something being touted as a "new design" should be deeply suspicious
of the quality of the design and the designer.
--
Bill Sloman, Nijmegen
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