> You're on the right track, but you need to re-calculate
> everything: V = I * R, not I/R.

d'oh!  What a dumb error !!

Well I gave it a shot, and things are working beautifully - a $30
boombox with one speaker removed and feeding a little transformer from a
3/4.5/6/9/12v voltage-selectable wall warts (giving what appears to be
about a 1:60 ratio at the max) produces a nice clean sinewave on the
output, and I can go to at least 250VAC out.  The "flute" tone on my 10
year old $80 casio keyboard is the signal source and is close to
sinewave, and after going thru the transformer it looks more or less
exact.  This is at 1Khz, the highest note I can get with the keyboard.
Now to get tone gen sw and try other frequencies.  I dunno how well
higher freqs will go thru the transformer - but tomorrow I'm going to
buy a honker power xformer from radio shack and hope for the best.  1Khz
is acceptable, but at 10Khz I get 2x the brightness from the wire.

This is going to make my life so much simpler.

Thanks for your post!  I had kind of assumed at much above 250Hz power
transformers wouldn't pass much of anything, but that's not the case
with this little trial one at least.

Best regards
Jesse




>
> Your overall approach should work OK, and I'd suggest trying a
> power transformer with a 120V primary and 24V secondary, with
> your amplifier feeding the secondary.
>
> I don't know whether this will give you absolutely optimal
> efficiency, but so long as nothing overheats, who cares.
>
> Try it and see.
>
> Dave
>
> Jesse wrote...
>
>
>>I'm in need of a power supply for electroluminescent wire.  I'm going to
>>be running many strands of 1 to 5 feet each.  I'm going to be running 24
>>strands per "box", and at approx 1W per strand on average (and not all
>>on at the same time) I think a 20W power supply will suffice.  I'd like
>>to be able to run multiple "boxes" as this project grows.
>>
>>But this is a somewhat unusual thing - 100VAC (can be anywhere from 50
>>to 150V, prefer 100V) @ 10Khz (also can be anywhere from 5-10Khz, and
>>variable would be nice too).
>>
>>I'm not very good with analog EE stuff and this is for an "art" project
>>happening shortly so taking any shortcuts now (and building it "right"
>>later) is desirable.  Also keeping it cheap...
>>
>>Here's what I'm thinking.
>>Use an audio amplifier (basic solid state cheapie which I already have).
>> 100W amp into 8 ohms: P=IV, V= I/R, so V= sqrt(P/R), so V= sqrt(100/8)
>>= 3.5V at full power, or sqrt(20/8) = 1.6V at 20W out.  Feed the audio
>>amp a 10Khz (or whatever) tone, and using a 30:1 to 40:1 transformer "in
>>reverse" to give me 50-140VAC out.  The transformer needs to handle up
>>to 10Khz.
>>
>>1) Does this make any sense?
>>2) What should the transformer rating be?  I see power ratings on (some)
>>transformers in mail-order catalogs.  Is this max power delivered to
>>load on secondary?
>>3) I'm guessing either a toroidal (as used in switching power supplies)
>>or an audio transformer (output stage of tube amps) would be the way to
>>go.  Correct?  Any recommeded sources?
>>
>>Any other suggestions?
>>Much thanks in advance!
>>Jesse
>
>
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>
>


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