Isolated, regulated, toroidal step down transformer AC power

[Mark]

Personally, I think it's very amusing to be called an arrogant pig by one
who then goes on to immediately infer that the power to "get to decide what
others should accept or believe" is a right that; a) Exists. b) Could be
earned, granted or perhaps even shared with others, at the decreation of the
right-holder(s).

Cognizant with this position is the logical assertion that the entry fee to
this exclusive club of 'deciders', as you so called them, is the
demonstration of superior knowledge or experience.

Perhaps not coincidently, I suggest that this hypothesis serves as a
tentative STRUCTURAL description for the organisation of?

....'Phil-o-philes'.

Just for my future edification, can anyone offer me a list of possible
members of the 'club of deciders' at 'aus.electronics'. To the uninitiated
contributor at this newsgroup, this would be an invaluable aid to 'fitting
in'.

Know what I mean?


"Phil Allison" <philallison@tpg.com.au> wrote in message
news:56uf4lF2b33i5U1@mid.individual.net...

"Mark Ilsley = ASININE FUCKWIT "


Incapable of argument.


( snip some of the CRAZIEST verbal garbage ever seen on this NG )


** Fucking, know nothing IDIOTS like this arrogant * PIG *

NEVER get to decide what others should accept or believe.


ROTFLMAO - this is absolutely bloody CLASSIC !!!

This ASININE, TOP POSTING, PITA BLOODY FOOL

has just gotta be another ADD fucked PIC programmer !!!!


What a bloody HOOOT & A HALF !!!!!!!

Lets all keep the CRETIN on the fishing line as long as possible !!

What TOP entertainment !!




........ Phil

 

[Alex Gibson]

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...

Well, according to the schematic it is +/- 15VDC after regulation. And I
believe it.

Yes, I believe it is half wave rectification. Something above +/- 15VDC,
after rectification of the 9VAC. The schematic does not say, probably it
is assumed knowledge.

I have already employed high ripple current Backgate capacitors after the
regulators, and in coupling the Op-amps, and at quite a few other points
throughout the power supply. Worked a treat in improving the sound.

Yes they are 7815 / 7915 regulators. I remember reading the spec for them
(not that I can find it now).

The case is simply stuffed full of large caps throughout the power supply
and analogue section, and it would simple break my hart to have to pull
them out and start over again (to eliminate the half wave rectification)

Which is why I made my objective the replacement of the 9VAC wall wart
power supply.

Too much to ask?

Why ?
If it works don't fix it.

If you need dual rails, thats the usual way to do it.
Half wave rectifier from a centre tapped transformer + linear regs.

Nice and cheap.

Alex

 

[Bob Parker]

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...

I have already employed high ripple current Backgate capacitors after the
regulators,

Ummm, can someone enlighten me as to what a Backgate capacitor
is...? I did the obligatory Google searching but didn't find anything
very informative.


Bob

 

[rebel]

On Wed, 28 Mar 2007 18:34:48 +1000, "Mark" <marknospampleaseilsley@dodo.com.au>
wrote:

The way I understand it, the regulation that already occurs within the
application can only operate within a tolerance of the regulating IC's
nominal input voltage.

Not exactly. There are precious few (if any) three-terminal regulators that
won't handle a 30V or 40V input for 15V out. Your configuration is far more
likely to suffer from UNDER-voltage out of the rectifier arrangement.

The application is using 15 Volt DC regulators
(output), after the bridge rectifier, and can only operate (+/- x%) of 15
volts DC input.

No, three-terminal regs don't work that way. Get a datasheet for a 7815 or 7915
and have a good read of the input voltage range. Let's see, 7815 ...

Dropout voltage (typical): 2.0V
Vin (max): 35V

So a 7815 will regulate as long as the input voltage doesn't exceed 35V or drop
below 17V on the troughs of the input waveform.

The rectification of (nominally) 9 VAC I understood to result in 18 VDC
(ignoring any small voltage drop across the diodes).

It may be small but it isn't insignificant. And I don't like your rectification
theory either.

So even when the input voltage is nominal,
the input voltage to the regulating IC's is only within 20% of their nominal
output.

The Vin-Vout capability of (again, 3-terminal) regs is a spec figure you'll find
on the data sheet, often termed drop-out voltage. See above. It's *not* a
percentage thing. If your input drops (even on transients) to 2V above your 15V
output, or less, you will lose regulation. 20% of 15V is 3V which - if your
rectifier is really providing 18V DC - is barely enough, and ripple at any sort
of load will kill you.

Now what happens if the domestic supply voltage is not nominal?

If the domestic supply comes in at 264 VAC (+10%), the existing linear
regulator

I think you mean transformer

now supplies 9.9 VAC to the application, the bridge rectifier
doubles that to 19.8 VAC.

I don't like your rectifier model, but let's ignore that for the moment.

The input voltage to the regulating IC's is now
only within 40% of their nominal output!

They should be happier. Warmer, but happier. Realise also that the output of
your rectifier system will show significant ripple as load current increases,
and those dips threaten the very regulation those regulators are trying to
provide.

Your concept of how regulators work is more than a worry. And IMNSHO it
unperpins all your problems.

I monitor the domestic supply and regularly see voltages coming into our
house outside the range of +/- 10%.

One solution, of course, would be to redesign the power supply within the
application's case, including upgrading the regulating IC's input voltage
tolerance to at least 40% of its output, if such an IC can be found!

Read the data sheet, and understand what a 3-terminal reg does.

However space within the applications case would not allow for a toroidal
transformer, which I consider to be the optimum solution for a number of
reasons that I don't need to explain here (or maybe they will insist that I
do that as well?!!), and I have already invested considerable effort (and a
small amount of money) in upgrading the capacitors within the existing
application's power supply and really don't want to loose out on the already
considerable improvements I have made therein.

Throwing bulk cap around will obviously improve (aka mask) the regulation
situation. But it is masking the symptoms, not fixing the cause.

You mentioned in another post that this is accompanying a move from a 9VAC
wall-wart to a hopefully better transformer.

What I sincerely suggest you do is (in order):

(a) Get the data sheets for the regulators that you are using. If they aren't
7815/7915 then I feel compelled to ask why not.

(b) Measure (even with a DMM) the input voltage to the regulator(s) and
convince yourself that you have enough headroom to operate properly. Better
still if you check the ripple with a CRO too. Even better, get a CRO and watch
the waveform applied to the input of the regulators, and load/unload teh system
so that the ripple can be quantified.

(c) Check whether the regs are running hot to touch.

(d) Try a 12VAC wall wart, unless the DCin to the regs is already 23V or more.

Quite frankly, I am astounded and reviled that such a simple request has
generated such a vile reaction from this group. I can only assume that it is
because they, like me, were unable to Goggle a suitable design. So as to
maintain their allusion of expertise and so they hide their inability to
self-design a suitable solution, with insults!

Quite frankly, I am astounded that you seemed to think that these problems are
best solved by shooting for an (affordable) transformer offering 1% line
regulation. If that were the best solution, such transformers would abound, and
Google would have turned up a mutitude of solutions for you. Rather, the
solution to such requirements have been de rigeur for decades, earning the tag
classical.

Your request was further obfuscated - and the task of steering you towards a
sound and achievable/affordable solution - by giving more of your planned
solution than the description of the application and the problem.

I wonder what would happen if I took a simular request for such a simple
thing to another newsgroup, say 'us.electronics', and pointed out to them
that 'aus.electronics' does not have a single contributor who can satisfy
the request. I wonder what they would say. "Too difficult", do you think?

No, they'd wonder why you were searching for an electronic sledgehammer.

Whether you choose to follow my, or anyone else's, suggestions is up to you.
But among the flaming, you have been given more than enough leads to achieve a
sensible outcome.

And please don't top-post

--

"rebel" <me@privacy.net> wrote in message
news:9cfj03lh21i2v84iq298n08u61ththollf@4ax.com...
On Tue, 27 Mar 2007 22:59:44 +1000, "Mark"
marknospampleaseilsley@dodo.com.au
wrote:

Yes, I really do need 9 VAC for my application.

Within the application, the 9 VAC is rectified, filtered, regulated (to
+15
VDC and -15 VDC) and then filtered again.

which removes the need for any tight regulation of the 9VAC.

So the input needs to be regulated to within about (+ or -) 1% 9 VAC.

Nah, THAT's bullshit. (Hint: Just think for a moment what effect an
increase or
decrease of 0.5V in your AC 9V will have on the REGULATED DC rails.)

 

[Alex Gibson]

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a43dc$0$24869$c30e37c6@pit-reader.telstra.net...

It certainly would be reassuring to know that I have more head room than I
remember.

Show me your spec please. I remember reading something less (much less),
but I haven't got it in front of me.

Maybe if you bothered looking at the datasheets for the devices you are
using.
Usual first step before using a device is read the datasheet or manual.

For a 7815
http://www.fairchildsemi.com/pf/LM/LM7815.html
http://www.national.com/ds/LM/LM340.pdf

input range is 17.5V to 30V DC.
Need minimum of 17.5 to get regulated 15V output.

Using a simple AC circuit + bridge rectifier or diodes + linear reg is a lot
cheaper and simpler than mucking around with AC regulation.

May not be the most energy efficient circuit but is simple and easy to fault
find.
Also a less noise than any switchmode or boost/buck converter circuit.

Alex

 

[Mark]

In retrospect, it was a vague question that he begged me to ask of myself.

Maybe the 'value' he refers to is the peak value of current under load, or
was he talking about the peak positive value and peak negative value of the
voltage (?) in the sine wave, which is what I thought him to mean.

I suppose only he can say what he meant.


"Phil Allison" <philallison@tpg.com.au> wrote in message
news:56u5guF2ak4onU1@mid.individual.net...

"Mark Ilsley = UTTER FUCKWIT "



You are assuming that I had a perfect 9 VAC sine wave input to my
application.


** No he is not - YOU FUCKING TENTH WIT !!



What I DO have is an very imperfect NOMINAL 240 VAC, domestic supply,
like everybody else.


** Then accept the fact that regulating the AC voltage is NOT required.


This ASININE, TOP POSTING, PITA DAMN FOOL

Just gotta be a school boy wanker.

What a bloody HOOOT !!!!!!!

Lets all keep the CRETIN on the fishing line as long as possible !!

What top entertainment !!



....... Phil

 

[Poxy]

"Bob Parker" <bobp.deletethis@bluebottle.com> wrote in message
news:460a5bc0$0$7400$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...

I have already employed high ripple current Backgate capacitors after
the
regulators,


Ummm, can someone enlighten me as to what a Backgate capacitor
is...? I did the obligatory Google searching but didn't find anything
very informative.

My guess? They're "acoustically transparent" and cost a bomb.

 

[Mark]

*Black Gate. I don't know how I can live with myself.


"Bob Parker" <bobp.deletethis@bluebottle.com> wrote in message
news:460a5bc0$0$7400$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...

I have already employed high ripple current Backgate capacitors after
the regulators,


Ummm, can someone enlighten me as to what a Backgate capacitor is...? I
did the obligatory Google searching but didn't find anything very
informative.


Bob

 

[dmm]

On Mon, 26 Mar 2007 22:59:59 +1000, "Mark" <marknospampleaseilsley@dodo.com.au> wrote:

Can anybody point me to a good design of same.

240 VAC in, 9 VAC out.

Just about any audio amplifier and a sine wave generator will do the job.

What exactly is it that you want to achieve?

 

[Bob Parker]

On 28/03/2007 22:50 Poxy wrote:

"Bob Parker" <bobp.deletethis@bluebottle.com> wrote in message
news:460a5bc0$0$7400$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...
I have already employed high ripple current Backgate capacitors after
the
regulators,

Ummm, can someone enlighten me as to what a Backgate capacitor
is...? I did the obligatory Google searching but didn't find anything
very informative.

My guess? They're "acoustically transparent" and cost a bomb.

Correct (see my other post with the info). Just the thing for
transparently filtering 100Hz ripple.

Bob

 

[Poxy]

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a43dc$0$24869$c30e37c6@pit-reader.telstra.net...

It certainly would be reassuring to know that I have more head room than I
remember.

Show me your spec please. I remember reading something less (much less),
but
I haven't got it in front of me.

You haven't tried Googling 7815 datasheet?

I think you also need to revise basic power supply design, in particular,
the manner in which regulators work, and the recommended filtering
configuration on the input and output of the regulator.

As others have pointed out, it may well be that your AC power supply isn't
supplying adequate voltage to prevent one or both of the regulators dropping
out under load.

I am sure that you can appreciate that since I am replacing a wall-wart
power supply with a toroidal step down transformer, the cost of an
additional IC regulator is rather trivial when compared to the cost of the
rest of the project.

No, I don't appreciate that perspective, because it isn't the most obvious
answer to what you've explained. The fact that you believe a regulator
requires an input voltage within some percentage, either postive or
negative, of the output voltage underpins where your thinking has gone
wrong.

You're also convinced the issue is overvoltage, whereas looking at the whole
system, it looks more like the AC transformer isn't putting out enough
voltage. It could well be that another plug pack with a higer output voltage
and suitable current rating would solve the problem, or it could be that the
plugpack you have is a dud.

The application certainly occasionally behaves erratically (on/off
clipping
of output) and I know that this behaviour coincides with over voltage
supply
problems. I monitor the domestic supply using software which queries and
records data from an UPS. So there is no doubt about the cause. 100%
correlation.

Possibly, but there's a much more obvious answer that does a better job of
explaining your problem.

If the cost of certainty (solving the problem by putting in a bigger,
better
IC regulator) is about 10 bucks (and, apparently, putting up with a few
arse-clowns because I was foolish enough to ask for help @
'aus.electronics') then I can go the extra distance, I guess.

Perhaps if you had stated from the start that your plugpack-powered preamp
(I'm guessing) is exhibiting distortion and that you suspect a power supply
issue, you might have gotten more rigorous and methodical advice. The next
question would have been what are the regulators, what voltage is appearing
at the input of each regulator, and are they getting hot.

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.

Also, if you are asking for help and advice, it's polite to observe accepted
etiquette - that inlcudes refraining from top-posting particularly if asked
not to.

"Poxy" <pox@poxymail.com> wrote in message
news:MIqOh.2795$M.1126@news-server.bigpond.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a28af$0$24860$c30e37c6@pit-reader.telstra.net...
The way I understand it, the regulation that already occurs within
the
application can only operate within a tolerance of the regulating
IC's
nominal input voltage. The application is using 15 Volt DC regulators
(output), after the bridge rectifier, and can only operate (+/- x%)
of
15
volts DC input.

A common 7815 regulator will put out a stable 15v for input voltages
between
17.5v and 30v. That's plenty of headroom for any overvoltage situation
on
the mains side.

 

[Bob Parker]

On 28/03/2007 22:53 Mark wrote:

*Black Gate. I don't know how I can live with myself.


"Bob Parker" <bobp.deletethis@bluebottle.com> wrote in message
news:460a5bc0$0$7400$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...
I have already employed high ripple current Backgate capacitors after
the regulators,

How could I not have realized that's what you meant?
For everyone's edification, from
http://www.hificollective.co.uk/components/black_gate_caps.html ....


Black Gate Electrolytic Capacitors
----------------------------------

There are very few audio parts that promise a guaranteed improvement
when replacing practically any other part, but this is what the BLACK
GATE™ capacitors actually do. Exchanging any electrolytic capacitor
anywhere in the circuit of a CD-player, amplifier or in the crossover of
a speaker will greatly improve sound quality. BLACK GATE™ are recognised
worldwide as the best electrolytics capacitors money can buy.

 

[Phil Allison]

"Poxy"

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.

** Oh yes they do - plus a whole lot more besides.

The likes of " Mark Ilsley " are among the most vile creatures infesting
the face of the earth.

A bullet to the forehead would be far too kind a fate for an individual who
has continually tortured so many innocents for so many years.

No surprise that a prick like you is in sympathy with this oxygen thief.

Cos YOU are another one of the same fucking pukes.





........ Phil

 

[Mark]

BUT I DON'T want to eliminate the half wave rectifier!!! It is pre-existing
inside the application.

I don't want to alter the application, at all and I would prefer not even to
discuss it.

I would like to point out that my original question deliberately had NOTHING
to do with the application. The easiest way to eliminate the unwanted
discussion is to not provide information on the application.

So, WE are stuck with AC as an input to the application. I wanted to
eliminate the AC/AC wall-wart transformer (which uses an Iron core
transformer) and replace if with a Toroidal core transformer.

Do I need to justify this choice as well?


"Alex Gibson" <news@alxx.org> wrote in message
news:56v3u8F2b6nkvU1@mid.individual.net...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a3520$0$24857$c30e37c6@pit-reader.telstra.net...
Well, according to the schematic it is +/- 15VDC after regulation. And I
believe it.

Yes, I believe it is half wave rectification. Something above +/- 15VDC,
after rectification of the 9VAC. The schematic does not say, probably it
is assumed knowledge.

I have already employed high ripple current Backgate capacitors after the
regulators, and in coupling the Op-amps, and at quite a few other points
throughout the power supply. Worked a treat in improving the sound.

Yes they are 7815 / 7915 regulators. I remember reading the spec for
them (not that I can find it now).

The case is simply stuffed full of large caps throughout the power supply
and analogue section, and it would simple break my hart to have to pull
them out and start over again (to eliminate the half wave rectification)

Which is why I made my objective the replacement of the 9VAC wall wart
power supply.

Too much to ask?

Why ?
If it works don't fix it.

If you need dual rails, thats the usual way to do it.
Half wave rectifier from a centre tapped transformer + linear regs.

Nice and cheap.

Alex

 

[Phil Allison]

" Mark Ilsley = UTTER FUCKING LIAR "

BUT I DON'T want to eliminate the half wave rectifier!!! It is
pre-existing inside the application.

** Hey - you asinine CUNT.

YOU do not have the tiniest clue what a " half wave rectifier " is.

Cos you are a lying, fucking ass.

I don't want to alter the application, at all and I would prefer not even
to discuss it.

I would like to point out that my original question deliberately had
NOTHING to do with the application. The easiest way to eliminate the
unwanted discussion is to not provide information on the application.

** It don't matter a RAT'S FUCK what some vile, brain dead, autistic,
delusional CUNTHEAD might be psychotic enough to believe is not necessary
for other people to know.

When it is.

So, WE are stuck with AC as an input to the application. I wanted to
eliminate the AC/AC wall-wart transformer (which uses an Iron core
transformer) and replace if with a Toroidal core transformer.

** Got news for YOU - CUNT !!

Toroidal mains transformers have all got " IRON " cores too.

GOSS to be precise.

Do I need to justify this choice as well?

** Absofuckinglutely !!!!!!!!!!!!!!!

Cos toroidal mains transformers are * NOT LEGALLY APPROVED * as SAFE
for the same applications that plug packs ALL are.

Cos they have no better voltage regulation than plug packs of the same VA
rating - most are worse.

And because NO common AC supply transformer regulates against mains
variations.

Because they do not need to !!!!!!!!!!!!!!


THIS is absolutely bloody CLASSIC !!!

This ASININE, TOP POSTING, PITA DAMN FOOL

has just gotta be another ADD fucked audiophool MORON !!

What a bloody HOOOT !!!!!!!

Lets all keep the CRETIN on the fishing line as long as possible !!

What top entertainment !!





......... Phil

 

[Mark]

Three things:

1) "7815" gives about 4 million hits on Goggle.

2) I asked for the help a little over 48 hours ago, and since that time I
have had to suffer about 30 attacks, but NO HELP what-so-ever.

3) I have a family and one particular dependant who is bed ridden.

What did you expect from me?

"Poxy" <pox@poxymail.com> wrote in message
news:mHtOh.2873$M.1140@news-server.bigpond.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a43dc$0$24869$c30e37c6@pit-reader.telstra.net...
It certainly would be reassuring to know that I have more head room than
I
remember.

Show me your spec please. I remember reading something less (much less),
but
I haven't got it in front of me.

You haven't tried Googling 7815 datasheet?

I think you also need to revise basic power supply design, in particular,
the manner in which regulators work, and the recommended filtering
configuration on the input and output of the regulator.

As others have pointed out, it may well be that your AC power supply isn't
supplying adequate voltage to prevent one or both of the regulators
dropping
out under load.

I am sure that you can appreciate that since I am replacing a wall-wart
power supply with a toroidal step down transformer, the cost of an
additional IC regulator is rather trivial when compared to the cost of
the
rest of the project.

No, I don't appreciate that perspective, because it isn't the most obvious
answer to what you've explained. The fact that you believe a regulator
requires an input voltage within some percentage, either postive or
negative, of the output voltage underpins where your thinking has gone
wrong.

You're also convinced the issue is overvoltage, whereas looking at the
whole
system, it looks more like the AC transformer isn't putting out enough
voltage. It could well be that another plug pack with a higer output
voltage
and suitable current rating would solve the problem, or it could be that
the
plugpack you have is a dud.

The application certainly occasionally behaves erratically (on/off
clipping
of output) and I know that this behaviour coincides with over voltage
supply
problems. I monitor the domestic supply using software which queries and
records data from an UPS. So there is no doubt about the cause. 100%
correlation.

Possibly, but there's a much more obvious answer that does a better job of
explaining your problem.

If the cost of certainty (solving the problem by putting in a bigger,
better
IC regulator) is about 10 bucks (and, apparently, putting up with a few
arse-clowns because I was foolish enough to ask for help @
'aus.electronics') then I can go the extra distance, I guess.

Perhaps if you had stated from the start that your plugpack-powered preamp
(I'm guessing) is exhibiting distortion and that you suspect a power
supply
issue, you might have gotten more rigorous and methodical advice. The next
question would have been what are the regulators, what voltage is
appearing
at the input of each regulator, and are they getting hot.

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.

Also, if you are asking for help and advice, it's polite to observe
accepted
etiquette - that inlcudes refraining from top-posting particularly if
asked
not to.





"Poxy" <pox@poxymail.com> wrote in message
news:MIqOh.2795$M.1126@news-server.bigpond.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a28af$0$24860$c30e37c6@pit-reader.telstra.net...
The way I understand it, the regulation that already occurs within
the
application can only operate within a tolerance of the regulating
IC's
nominal input voltage. The application is using 15 Volt DC
regulators
(output), after the bridge rectifier, and can only operate (+/- x%)
of
15
volts DC input.

A common 7815 regulator will put out a stable 15v for input voltages
between
17.5v and 30v. That's plenty of headroom for any overvoltage situation
on
the mains side.

 

[Bob Parker]

On 29/03/2007 00:00 Mark wrote:

Three things:

1) "7815" gives about 4 million hits on Goggle.

2) I asked for the help a little over 48 hours ago, and since that time I
have had to suffer about 30 attacks, but NO HELP what-so-ever.

3) I have a family and one particular dependant who is bed ridden.

What did you expect from me?

I haven't been paying close attention to this thread, but no item of
audio (or any other mains-powered) equipment which is working properly
is going to be affected by tiny mains voltage variations. If that's
happening, then it's faulty and it should be looked at and repaired by
someone who understands electronics.
All this talk about toroidal transformers, voltage regulators and
acoustically transparent capacitors seems irrelevant, or did I miss
something by not reading everything?
BTW: 'wall wart' is another Americanism creeping into the Australian
vernacular. I suppose one day we'll have 117V 60Hz mains and beoome the
51st or 52nd or whatever it is state of the USA.

 

[Poxy]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:56v86vF2ai8ouU1@mid.individual.net...

"Poxy"

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.



** Oh yes they do - plus a whole lot more besides.

The likes of " Mark Ilsley " are among the most vile creatures infesting
the face of the earth.

Oh be nice and go to bed Phil.

 

[Poxy]

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a7519$0$24869$c30e37c6@pit-reader.telstra.net...

Three things:

1) "7815" gives about 4 million hits on Goggle.

A Google on 7815 datasheet gets you the answer - very first result.
Secondly, it isn't really about the specific attributes of the 7815 - as
soon as you've had anything to do with power supplies, you get familiar with
some very basic rules, one of which is that you need 2-3v extra at the input
of a regulator for it to work - that applies to 7805s, 7812s etc.

2) I asked for the help a little over 48 hours ago, and since that time I
have had to suffer about 30 attacks, but NO HELP what-so-ever.

That's because you didn't provide sufficient information from the start, and
I don't mean to be rude, but what you initially suggested was absurd - it
was. Really. It might have made sense to you given your background, but to
anyone with experience in almost any field of electronics, regulated power
supplies are such common and basic things that we pretty much all understand
how they work, the issues that arise and how to deal with them.

What you said initially was the equivalent of saying: "How can I synthesise
better fuel?" Then you say "I've purchased lots of really expensive fuel
filters, which are black by the way - that hasn't helped, so I clealry need
to re-sythesise my existing fuel to make it more consistent".

Everyone laughs at you. Particulalry when we discover how much those fuel
filters cost.

Finally you say: "My engine is running badly, I think it's a fuel problem".

And if you were really being straight-up with us, you'd also say "Actually,
I built the engine, it's running badly, does anyone want to buy some really
good fuel filters?"

3) I have a family and one particular dependant who is bed ridden.

What did you expect from me?

I'm honestly sorry to hear that one of your family is ill, and I'm also
sorry that you've had to endure such unpleasant language and abuse, but it's
Usenet, a base level of mocking and general derision comes with the
protocol.

If you really want help, rather than seeking confirmation of your various
theories, just tell us what the actualy device is, who designed and built
it, what the voltage is at the input of the regulators is and what caps you
have on each side of the regulator.

Oh, and maybe refrain from top-posting - it really does annoy people.

"Poxy" <pox@poxymail.com> wrote in message
news:mHtOh.2873$M.1140@news-server.bigpond.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a43dc$0$24869$c30e37c6@pit-reader.telstra.net...
It certainly would be reassuring to know that I have more head room
than
I
remember.

Show me your spec please. I remember reading something less (much
less),
but
I haven't got it in front of me.

You haven't tried Googling 7815 datasheet?

I think you also need to revise basic power supply design, in
particular,
the manner in which regulators work, and the recommended filtering
configuration on the input and output of the regulator.

As others have pointed out, it may well be that your AC power supply
isn't
supplying adequate voltage to prevent one or both of the regulators
dropping
out under load.

I am sure that you can appreciate that since I am replacing a wall-wart
power supply with a toroidal step down transformer, the cost of an
additional IC regulator is rather trivial when compared to the cost of
the
rest of the project.

No, I don't appreciate that perspective, because it isn't the most
obvious
answer to what you've explained. The fact that you believe a regulator
requires an input voltage within some percentage, either postive or
negative, of the output voltage underpins where your thinking has gone
wrong.

You're also convinced the issue is overvoltage, whereas looking at the
whole
system, it looks more like the AC transformer isn't putting out enough
voltage. It could well be that another plug pack with a higer output
voltage
and suitable current rating would solve the problem, or it could be that
the
plugpack you have is a dud.

The application certainly occasionally behaves erratically (on/off
clipping
of output) and I know that this behaviour coincides with over voltage
supply
problems. I monitor the domestic supply using software which queries
and
records data from an UPS. So there is no doubt about the cause. 100%
correlation.

Possibly, but there's a much more obvious answer that does a better job
of
explaining your problem.

If the cost of certainty (solving the problem by putting in a bigger,
better
IC regulator) is about 10 bucks (and, apparently, putting up with a few
arse-clowns because I was foolish enough to ask for help @
'aus.electronics') then I can go the extra distance, I guess.

Perhaps if you had stated from the start that your plugpack-powered
preamp
(I'm guessing) is exhibiting distortion and that you suspect a power
supply
issue, you might have gotten more rigorous and methodical advice. The
next
question would have been what are the regulators, what voltage is
appearing
at the input of each regulator, and are they getting hot.

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.

Also, if you are asking for help and advice, it's polite to observe
accepted
etiquette - that inlcudes refraining from top-posting particularly if
asked
not to.





"Poxy" <pox@poxymail.com> wrote in message
news:MIqOh.2795$M.1126@news-server.bigpond.net.au...

"Mark" <marknospampleaseilsley@dodo.com.au> wrote in message
news:460a28af$0$24860$c30e37c6@pit-reader.telstra.net...
The way I understand it, the regulation that already occurs
within
the
application can only operate within a tolerance of the regulating
IC's
nominal input voltage. The application is using 15 Volt DC
regulators
(output), after the bridge rectifier, and can only operate (+/-
x%)
of
15
volts DC input.

A common 7815 regulator will put out a stable 15v for input voltages
between
17.5v and 30v. That's plenty of headroom for any overvoltage
situation
on
the mains side.

 

[Phil Allison]

" Poxy"

That said, *nobody* deserves the kind of response and language that a
certain person has used in this thread.

** Oh yes they do - plus a whole fucking lot more besides.

The likes of " Mark Ilsley " are among the most VILE parasites infesting
the face of the earth.

A bullet to the forehead would be far too kind a fate for this cretin who,
due
to his manifest, congenital mental defects has continually tortured the
lives of
so many innocents for so many years.

No surprise that a * total prick * like POXY is in sympathy with this
utterly disgusting oxygen thief.


Cos POXY is another of the same sub human species.


Peeeeeuuuukeeeeeee !!




........ Phil