Anton Gÿsen wrote:

Eeyore wrote:
Anton Gÿsen wrote:

I have a capacitor rated 0.22 microfarads 250 V AC which came out of a
broken power tool (it was wired in series with the mains supply IIRC) -
would that do?

GOD, you're thick. You shouldn't be allowed ANYWHERE NEAR electricity.

Keep spreading the love, Graham.

Your idea was so stupid it deserved that reponse. People like you meddling
with electricity can KILL people.

Graham

Anton Gÿsen wrote:

Eeyore wrote:
Anton Gÿsen wrote:

But I don't care about the drop-out in sound when I switch my TV on.

So why are you whining about it ?

It makes me think that the DAC and/or its PSU is poorly designed as it
can't cope with a short power surge.

There shouldn't BE a 'surge'. Not for an effing 14" TV ! Something more fundamental is
wrong.


I do pull the plug but it's a drag... I'd rather a physical power switch
in an accessible place.

About 45 mins ago I was using a '4 way extension' with individual power switches.
Too much trouble for you to find one ?

No, I'm just a cheapskate.

As well as an idiot ?

Graham

Serge Auckland wrote:

"Anton Gÿsen" wrote
Eeyore wrote:
Anton Gÿsen wrote:

I have a capacitor rated 0.22 microfarads 250 V AC which came out of a
broken power tool (it was wired in series with the mains supply IIRC) -
would that do?

GOD, you're thick. You shouldn't be allowed ANYWHERE NEAR electricity.

Keep spreading the love, Graham.

What I'm sure Graham meant to say was that the capacitor you have was
designed to go across the mains switch of the power tool as a suppressor. It
would only be in series with the mains supply when the switch was off, and
be shorted out by the switch when switched on. I would not want to use
capacitor rated at only 250 volts on the mains, I would prefer one rated at
least 350v.

NEVER put capacitors across switches without a serious watty R of about 100 ohms
in series too. I've seen the results. DRAMATIC barely explains it.

Ever seen a capacitor literally EXPLODE and shower the internals with metallised
foil ?

Graham

Anton Gÿsen wrote:

Serge Auckland wrote:
"Anton Gÿsen" wrote
Eeyore wrote:
Anton Gÿsen wrote:

I have a capacitor rated 0.22 microfarads 250 V AC which came out of a
broken power tool (it was wired in series with the mains supply IIRC) -
would that do?

GOD, you're thick. You shouldn't be allowed ANYWHERE NEAR electricity.

Keep spreading the love, Graham.

What I'm sure Graham meant to say was that the capacitor you have was
designed to go across the mains switch of the power tool as a
suppressor. It would only be in series with the mains supply when the
switch was off, and be shorted out by the switch when switched on. I
would not want to use capacitor rated at only 250 volts on the mains, I
would prefer one rated at least 350v.

Thanks.

And it MUST be 'X-rated'. Don't expect to find it in Maplin.

Only X and Y rated caps are approved for use in mans application.

X for 'across the mains'
Y (pref Y2) for 'mains to ground'

See BSEN 60065.

Unless you fancy an early death of course.

Graham

Arny Krueger wrote:

The good news is that a full-wave rectifier will turn 12 VAC into about 17
volts DC, but the bad news is that the voltage drop across the regulator
plus a reasonable allowance for low line voltages will pretty well eat up
the 5 volt advantage.

Perfectly true and don't forget ripple voltage (min value of) too.

Graham

Arny Krueger wrote:

"Eeyore" wrote

He's in the UK though.

Yes, but you've got to have power line fluctuations, and the slings and
horrors of field operations.

You don't really get power line fluctuations of any note in the UK. Better
infrastructure you see.

Graham

Arny Krueger wrote:

When you were designing power supplies, did you use 12 volt transformers to
produce 12 volts DC regulated, or did you throw in a safety factor?

I never went as low as 12V.

15V was my lowest ever and for several recent decades I was using +/- 17V for
extra headroom.

Of course do you mean the O/C transformer voltage ? With the lossy but very low
field R cores I was speccing up to 25-0-25 O/C IIRC to get a well regulated +/-
17V.

We did test them down to 208V for 'low line' operation though. Never had more
than a few hundred uV of audio band noise on the rails.

Graham

Arny Krueger wrote:

"Eeyore" wrote
Adrian C wrote:

Use a PC switchmode power supply?

To make it sound REALLY crappy ?

I've run a lot of audio gear off of PC power supplies without bad things
happening.

Car audio stuff is pretty happy running off of the 12 volt lines, which have
pretty impressive current ratings.

Car power rails are massively noisy so if course they're designed to cope with
that.


I've seen a lot of switchmode supplies in DVD players and the like.

So ? You can make an SMPS very quiet if you know how. I do for example.

Graham

Phil Allison wrote:

"Eeyore"

http://www.maplin.co.uk/Module.aspx?ModuleNo=13156

I don't see any safety approval mark.

** Such switches are approved for use in 2 wire circuits - ie lamps.

Doesn't exempt them from safety tests.

Graham

Phil Allison wrote:

"David Looser"

The CE mark is required for power supplies sold in Europe and India.


But bringing this back to the original point, the operative word above is
"sold".

** No it is not the " operative word" at all - it would not matter if you
gave them away.

If you put a transformer in a box for your own use you don't need "type
approval" (though if it's dangerous and somebody dies as a result you
might find yourself up on a charge of manslaughter).

** The issue here is NOT what someone might **choose** to do in the
privacy of their own workshop - but rather one of folk instructing
someone via a public forum ( hence ANYONE) to build an unsafe electrical
device that would not be permitted on sale BECAUSE it is unsafe.

I use my real name on usenet, so do you and many others - so are legally
responsible for what we post.

It is just NOT ON for any poster to declare he has no concern for safety
laws as the ****wit OP just did here.

Quote from Anton Gysen:

" Balls to health and safety. "

What an utter ass.

Agreed. Especially with his wonky mains wiring.

Graham