Replacement wall-wart help needed

[tele...@gmail.com]

This is a total "noob" question and I have done some searches but want to be sure before I go and purchase a replacement.

I own something called a Bitscope which I use for tinkering with electronics. It an older one and I'm pretty sure the wall-wart power supply is dead. The creator of the Bitscope isn't responding to my emails so I'm sorta stuck trying to find a replacement one and so far no luck on an exact match.
If I'm reading the PS correctly it says that the output is:

10VAC
1A

My electronics knowledge is pretty basic, but am I right in that I could choose a supply that is rated higher in amperage but would need the exact voltage specified? I've looked on digikey and a few places and can't seem to find a supply that puts out 10VAC.

Any help/info would be greatly appreciated.

thanks,
~brian

[Ecnerwal]

In article <e34985b6-de75-474c...@googlegroups.com>,

First off, check the power adapter with a voltmeter. If you don't have
one, go buy at least a cheap one - less than $10 will get you some piece
of chinese junk that will be handy for working on the car or anyplace
else you wouldn't want to take a nice one lest you should drive over it,
and see if the wall wart is, or is not, putting out 10VAC.

There are only a few things that might kill a simple transformer
wall-wart like this, so odds are good (barring you've already tested it
and not mentioned that fact) that the more likely to die device is what
it plugs into, rather than itself.

Yes, you need 10 VAC and any amperage 1 or above will work (note that
his may be written as 1000mA - just one amp in different notation, like
100 cents to a dollar.) Whether it would work on 9VAC or 12VAC is not
something we can figure out - some things are quite picky about supply
voltage, others not so much. Best to stick with what it used originally
unless you hear otherwise from the unresponsive developer.

ebay (also known as sleazebay, so caveat emptor to the max) is probably
your best source for a 10VAC wall wart if it's actually dead. They are
out there, especially in the used market, just not stunningly common
these days. I think they were a common voltage for modem wall-warts at
one point.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

[Rich Webb]

Since it's rated as AC then you know that there's a converter inside and
so it should be fairly forgiving in terms of what you can feed it. Let's
see now <clickety click> Yup, it's a linear:
<http://www.bitscope.com/design/hardware/pdf/Bs11-2.PDF>

A 12 VAC wart may be easier to find than a 10 and it'll work fine.

--
Rich Webb Norfolk, VA

[Ecnerwal]

In article
<MyNameForward-473...@news.eternal-september.org>,

Ecnerwal <MyName...@ReplaceWithMyVices.Com.invalid> wrote:
> Whether it would work on 9VAC or 12VAC is not
> something we can figure out

Rich Webb posted:

<http://www.bitscope.com/design/hardware/pdf/Bs11-2.PDF>

And I sit corrected. 10-12VAC right there on the drawing.

[Rich Webb]

On Sun, 19 Aug 2012 16:33:37 -0400, Ecnerwal
<MyName...@ReplaceWithMyVices.Com.invalid> wrote:

>In article
><MyNameForward-473...@news.eternal-september.org>,
> Ecnerwal <MyName...@ReplaceWithMyVices.Com.invalid> wrote:
>> Whether it would work on 9VAC or 12VAC is not
>> something we can figure out
>
>Rich Webb posted:
>
><http://www.bitscope.com/design/hardware/pdf/Bs11-2.PDF>
>
>And I sit corrected. 10-12VAC right there on the drawing.

Yes, the regulators will run a little hotter but (presumably) they've
accounted for that in the design.

OTOH, they used Comic Sans so who knows? ;-)

[Bob Engelhardt]

Rich Webb wrote:
>...
> <http://www.bitscope.com/design/hardware/pdf/Bs11-2.PDF>
...

Since the OP's question has been answered, he shouldn't mind if I divert
this thread with a couple about the BitScope power supply.

1. What is the purpose of the choke on the Analogue Power common?

2. What is the purpose of diodes D12 & 13 on the Analogue Power inputs?
My guess would be to prevent the Digital Power section from drawing on
the A-P caps C19 & 20.

3. Why is there separate (but equal) regulators for analog & digital?

Thanks,
Bob

[fungus]

On Sunday, August 19, 2012 9:43:43 PM UTC+2, (unknown) wrote:
> This is a total "noob" question and I have done some searches but want to be sure before I go and purchase a replacement.
>
>
>
> I own something called a Bitscope which I use for tinkering with electronics. It an older one and I'm pretty sure the wall-wart power supply is dead. The creator of the Bitscope isn't responding to my emails so I'm sorta stuck trying to find a replacement one and so far no luck on an exact match.
>
> If I'm reading the PS correctly it says that the output is:
>
> 10VAC
>
> 1A
>

According to the web site, that's correct, yes.

http://www.bitscope.com/design/hardware/?p=power

>
>
> My electronics knowledge is pretty basic, but am I
> right in that I could choose a supply that is rated
> higher in amperage but would need the exact voltage
> specified?

Yes.

> I've looked on digikey and a few places and can't
> seem to find a supply that puts out 10VAC.
>

I'm not sure you'll find a simple wall-wart that
puts out AC. They're all DC.

Have you measured the output of the power supply
to make sure that's the problem?

If there's no output can you open it up and look
if there's a fuse inside?

[John G]

fungus wrote on 20/08/2012 :
> On Sunday, August 19, 2012 9:43:43 PM UTC+2, (unknown) wrote:
>> This is a total "noob" question and I have done some searches but want to be
>> sure before I go and purchase a replacement.
>>
>>
>>
>> I own something called a Bitscope which I use for tinkering with
>> electronics. It an older one and I'm pretty sure the wall-wart power supply
>> is dead. The creator of the Bitscope isn't responding to my emails so I'm
>> sorta stuck trying to find a replacement one and so far no luck on an exact
>> match.
>>
>> If I'm reading the PS correctly it says that the output is:
>>
>> 10VAC
>>
>> 1A
>>
>
> According to the web site, that's correct, yes.
>
> http://www.bitscope.com/design/hardware/?p=power
>
>
>>
>>
>> My electronics knowledge is pretty basic, but am I
>> right in that I could choose a supply that is rated
>> higher in amperage but would need the exact voltage
>> specified?
>
> Yes.
>
>> I've looked on digikey and a few places and can't
>> seem to find a supply that puts out 10VAC.
>>
>
> I'm not sure you'll find a simple wall-wart that
> puts out AC. They're all DC.

Please do not make Categorical statements about which you know
Nothing.

Many Modems and some small audio mixers use 10 volts AC to get + and -
supply rails.
The first one I picked up in my obsolete stuff heap was 10 volts AC 1
Amp. And it is just a simple iron and copper wall-wart. :-?

>
> Have you measured the output of the power supply
> to make sure that's the problem?
>
> If there's no output can you open it up and look
> if there's a fuse inside?

--
John G

[Rich Webb]

On Sun, 19 Aug 2012 19:31:43 -0400, Bob Engelhardt
<bobeng...@comcast.net> wrote:

>Rich Webb wrote:
> >...
> > <http://www.bitscope.com/design/hardware/pdf/Bs11-2.PDF>
>...
>
>Since the OP's question has been answered, he shouldn't mind if I divert
>this thread with a couple about the BitScope power supply.
>
>1. What is the purpose of the choke on the Analogue Power common?

I'd guess HF noise suppression to the outside world.

>2. What is the purpose of diodes D12 & 13 on the Analogue Power inputs?
> My guess would be to prevent the Digital Power section from drawing on
>the A-P caps C19 & 20.

Sounds plausible.

>3. Why is there separate (but equal) regulators for analog & digital?

Presumably to help isolate digital noise (lots of switching and fast
edges) from the analog section.

[tele...@gmail.com]

Wow, thanks for all of the excellent help (and info). I didn't realize I could just check the power supply output. For some reason I assumed it there would have to be a load attached. It's very possible the unit itself has gone belly up (it's almost 8 yrs old I believe).

Also good to know that a 12VAC one will work also.

You folks are thorough!

thanks,
~brian

[Michael Black]

On Sun, 19 Aug 2012, Bob Engelhardt wrote:

>
> 3. Why is there separate (but equal) regulators for analog & digital?
>

Someone else has already posted that it keeps noise from the digital logic
out of the supply to the analog.

But it's worth adding that the three terminal regulators were introduced
as "on card regulators". The plan was that you'd have a single supply of
transformer/diodes/filter capacitor and feed that to the various boards,
with each board having regulators to get to the proper voltage. It helped
isolate noise on the supply line, but also distributed the heat from the
regulators.

It didn't take long before the three terminal regulators were used in the
power supply, so many things not needing more than 1amp, might as well
power everything from the one regulator. And it does work, it's just the
initial vision was for something that used a lot more current than 1amp so
multiple regulators dealt with the current draw and had advantages.

The advantages are still there, and it's often worth considering using
multiple regulators rather than trying to figure out how to get more
current out of a 3 terminal regulator (as we've often seen).

And since those initial 1amp TO-3 regulators came out, there have been
much smaller 3terminal regulators, making it easier to split things up
with lower current levels.

Michael

[Michael Black]

On Sun, 19 Aug 2012, fungus wrote:

> On Sunday, August 19, 2012 9:43:43 PM UTC+2, (unknown) wrote:
>> This is a total "noob" question and I have done some searches but want to be sure before I go and purchase a replacement.
>>
>>
>>
>> I own something called a Bitscope which I use for tinkering with electronics. It an older one and I'm pretty sure the wall-wart power supply is dead. The creator of the Bitscope isn't responding to my emails so I'm sorta stuck trying to find a replacement one and so far no luck on an exact match.
>>
>> If I'm reading the PS correctly it says that the output is:
>>
>> 10VAC
>>
>> 1A
>>
>
> According to the web site, that's correct, yes.
>
> http://www.bitscope.com/design/hardware/?p=power
>
>
>>
>>
>> My electronics knowledge is pretty basic, but am I
>> right in that I could choose a supply that is rated
>> higher in amperage but would need the exact voltage
>> specified?
>
> Yes.
>
>> I've looked on digikey and a few places and can't
>> seem to find a supply that puts out 10VAC.
>>
>
> I'm not sure you'll find a simple wall-wart that
> puts out AC. They're all DC.
>

Considering they'd just be a transformer, then if that was true,
one could just dig out a suitable voltage and current transformer and hook
it up, though likely needing some box to make it safe.

But, there are plenty of AC adapters that put out AC. Sometimes the
AC is used for clocking (it's not a great example, but the power supply
for the Commodore 64 included 9vac for counting by the CPU but maybe for
incidental voltages). As someone pointed out, plenty of modems use AC
supplies, because they need multiple voltages, and it makes more sense to
use a stnadard AC out adapter than create an external power supply that
supplies the multiple voltages.

Don't forget that the whole reason for AC adapters (other than to make
portable equipment smaller, hence if you need to run it off AC power you
use the adapter at home) is to make UL and CSA approval easier. If they
have the transformer inside the unit, the unit has to be approved. If
they move the transformer to the AC adapter, it can be approved separately
since the unit doesn't have 120VAC roaming inside it. Since there's more
demand for AC adapters of standard voltage, the cost of approval can be
spread over the multiple units. If you have a piece of equipment that
will sell only a few units, using an external supply makes sense.

If you only need one voltage, (or can step it down to other voltages) it
makes sense to use an AC adapter with DC output. If you need multiple
voltages with different polarity, it makes sense to use an AC adapter with
AC output.

It's also worth noting that since the unit does specify an AC voltage,
then that shows that such things have to exist.

Michael

[fungus]

On Monday, August 20, 2012 2:07:03 AM UTC+2, John G wrote:

> fungus wrote on 20/08/2012 :
>
> > I'm not sure you'll find a simple wall-wart that
>
> > puts out AC. They're all DC.
>
>
> Please do not make Categorical statements about which you know
>
> Nothing.
>

Ooops! Something was lost in translation
(English isn't my everyday language).

I didn't mean to be categorical, I meant
you won't find them in everyday places.
Almost all electronic gadgets use DC
these days.

> The first one I picked up in my obsolete stuff heap was 10 volts AC 1
>
> Amp.

I think your obsolete stuff is older than my
obsolete stuff.

> And it is just a simple iron and copper wall-wart. :-?
>

Yes, it will be just an iron transformer
inside, very little to go wrong. If there's
no output from it then look for a fuse.

[Tom Biasi]

Before you go crazy check the wire where it meets the connector. Pull on
it a little (I said a little) and see if the insulation stretches, if it
does the wire is broken inside. This is quite common.

Tom

[BeeJ]

tele...@gmail.com was thinking very hard :

So if you bought a 120 VAC to 10 VAC (or 12 VAC) transformer and used
the cable from your dead walwart for the output side (wire nuts) and
screwed on an ac plug on the 120 VAC side (no soldering required) ...
then what? You would have a quick and cheap fix.

--
Present and unaccounted for.