too easy of a question

+-------+
+12V>----+---[1N4002>]--+-----+-----+----|IN OUT|---+--+8V
| |K | | | GND | |
|K [1N4746] | | +---+---+ |
[1N4002] | C | | [0.1]
| +---B [1000µF] | |
| E |25V | |
| | | | |
GND>-----+--------------------+-----+--------+-------+

Turns out the Diodes, Inc. half-watters and one-watters are the same
price, and they don't even list a quarter-watter with Digi-Key so I
just went with the one-watter,

On Sun, 05 Feb 2006 12:24:34 GMT, "Anthony Fremont" <spam_at_anywhere.com
wrote:


"John Fields" <jfields_at_austininstruments.com> wrote in message

Even better:
7808
+-------+
+12V>----+---[1N4002>]--+--------+------|IN OUT|---+--+8V
|K |K |+ | GND | |
[1N4002] [1N5355] [1000µF] +---+---+ [0.1]
| | |25V | |
GND>-----+--------------+--------+----------+-------+

With no current limiting, that'll be a bit rough on that Zener, won't it?

---
Depends on how much current the transient can pump through the Zener, and
for how long the transient lasts.

Sure, some current limiting wouldn't hurt, but the OP told us nothing
about what his load looks like, ---

How about this instead:
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=304881

---
They're essentially the same thing, 5 watt Zener diodes. Here's the data
sheet for the 1N5355:

http://www.onsemi.com/pub/Collateral/1N5333B-D.PDF

Note that it'll do 180 watts for 8.6ms, while the ST device claims 1000
watts for somewhere between 10 and 1000µs.

Multiply 180 watts by 8.6ms to make apples equal to apples and you get
1548 watts for the Motorola part!

On Sun, 05 Feb 2006 07:58:57 -0600, John Fields wrote:

On Sun, 05 Feb 2006 12:24:34 GMT, "Anthony Fremont" <spam_at_anywhere.com
wrote:


"John Fields" <jfields_at_austininstruments.com> wrote in message

Even better:
7808
+-------+
+12V>----+---[1N4002>]--+--------+------|IN OUT|---+--+8V
|K |K |+ | GND | |
[1N4002] [1N5355] [1000µF] +---+---+ [0.1]
| | |25V | |
GND>-----+--------------+--------+----------+-------+

With no current limiting, that'll be a bit rough on that Zener, won't it?

---
Depends on how much current the transient can pump through the Zener, and
for how long the transient lasts.

Sure, some current limiting wouldn't hurt, but the OP told us nothing
about what his load looks like, ---

How about this instead:
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=304881

---
They're essentially the same thing, 5 watt Zener diodes. Here's the data
sheet for the 1N5355:

http://www.onsemi.com/pub/Collateral/1N5333B-D.PDF

Note that it'll do 180 watts for 8.6ms, while the ST device claims 1000
watts for somewhere between 10 and 1000µs.

Multiply 180 watts by 8.6ms to make apples equal to apples and you get
1548 watts for the Motorola part!

Or, just use a real Transzorb.

I'd still put a hash choke between the
VBatt and the junction of the two diodes.

I'd still put a hash choke between the
VBatt and the junction of the two diodes.

I thought you liked hash...

I have a device that says it runs on 6-12 volts dc. I'd like to hook it up
to a car battery, but the alternators on such things exceed 12 volts (and
the battery at its 13..

So I should be able to hook a LM7812 and be good to go, right? or would
the 13.8 be too low for regulation. also these devices are going to be run
along some long lengths of wire, so I'll probably stick the regulator next
to the device, rather than near the battery. maybe stick to the lm7809
instead?

"Bob Monsen" <rcsurname_at_comcast.net> wrote in message
news:pan.2006.02.05.22.04.19.634022_at_comcast.net...
On Sun, 05 Feb 2006 17:18:50 +0000, Anthony Fremont wrote:
BTW, must you persist with those anti-creationist quotes in the sig
line? It is just a THEORY after all.

Despite what critics say, Darwin was a genius, pure and simple. Using

And you personally KNOW this how?

years of original research, he cracked a nut that people had been
trying
to crack for thousands of years, and did it with an elegant,
intuitively
obvious scheme.

I'm afraid that may be more your opinion than an actual fact. Seems to
me that evidence indicates that the nut is still a wee bit short of
being cracked.

These are all quotes from the man himself, not
'anti-creationist' quotes.

I know they are, but the ones you choose to post (aside from the one
here) seem to mostly be anti-creationist. I can't help but believe that
is intentional on your part. Are you trying to make some kind of
statement, or just surreptitiously preaching your brand of "religion" to
the world?

Seriously, I'd put allot more stock in Darwin's theories if they were
backed by a bit more hard evidence. In the 150 years since Darwin,
there has still not been one fossil found representing the so-called
missing link. Can you point me to something resembling proof of at
least one new species having evolved? It's a fact that scores
(depending upon whom you believe) of species become extinct every day,
and AFAICT there have been no new ones forming to take their place.
Certainly not scores every day or it would seem that would be quite
obvious IMO. I'm not saying this is some kind of proof of God, but it
certainly doesn't appear to be helping Darwin's case either.

The big bang theory is a pretty good theory too, if you can get past
that "tiny" problem of the first fraction of second and how no known
physics can explain what happened. Of course we're also left to wonder
about the blue shifted stars, and the fact that over 90% of the matter
in the universe seems to be hiding.

If you were joking, you need to supply a bit more context for folks to
'get it'. If not, well, I feel sorry for you. Trying to suppress
freedom

Gee Bob, I appreciate the thought but, I don't really need your
sympathy. You seem to be saying that belief in God is equivalent to
ignorance, is that about right?

of speech is, while apparently OK with the current US administration,
considered rude and obnoxious by most people. Do you shout down people
who

Oh...so now I'm trying to suppress freedom of speech, geez. If you
don't want a response to your sig lines, then you probably should think
about that.

you disagree with in person, like that narcissistic bully Bill
O'Reilly?

Er, um no, and how did O'Reilly come into this? At any rate, I don't
recall "shouting down" anyone, but some might think you are doing that
right now by putting many more words into my mouth than I said.

Do you support arresting people wearing tee-shirts that you disagree
with?

Oh man, you really are taking this way too seriously. You're only about
one step away from invoking Godwin already.

Oh, and how fast is that TVS? Will it kill all automotive transients
above
30V?

I'm no expert, but it's probably a pretty safe bet to say that it will
not "kill ALL automotive transients above 30V".

One thing that gets confused is that the word "theory" means something
different in science than it does in popular culture. In popular use,
"theory" refers to a mere notion or idea. In science a theory is the highest
level that a model of how-things-work can attain. It stays there until
disproven or replaced by a better theory.

And yes, the big bang theory is under revision as well. It may have to be
replaced. Many ideas have been proposed to explain new data and observations
that dont fit the previous model that was given the status of theory with
what was known then. Even my college Astronomy text from 25 years ago lacks
many discoveries that have been made since.

And I am talking about even in
our own solar system with the Kuiper Belt, Oort cloud, moons of gas giants,
NEOs, etc.

Just as Newton had his theories revised and expanded by Einstein, Darwin's
work will, and is, undergoing the same.

Sorry that I dont have anything to add to the electronics part of the
thread.