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Old 10th October 2006, 03:00 PM   #1
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Default Cheap toroid xfmrs for ESL audio

I recently ran into this listing for toroidal power transformers at $5 each-

http://www.halted.com/commerce/catal...=1160264716423

I emailed them to get an idea of the size and they came back with:

"The transformer is 2.2 in. x 1.2 in. and it,s weight is .64 lbs. We do not
have any additional spects."

This looks to me like about a 25VA core. A little small, but still useable in pairs.

I_F
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Old 15th October 2006, 06:24 PM   #2
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Default Re: Cheap toroid xfmrs for ESL audio

Quote:
Originally posted by I_Forgot
I recently ran into this listing for toroidal power transformers at $5 each-

http://www.halted.com/commerce/catal...=1160264716423

I emailed them to get an idea of the size and they came back with:

"The transformer is 2.2 in. x 1.2 in. and it,s weight is .64 lbs. We do not
have any additional spects."

This looks to me like about a 25VA core. A little small, but still useable in pairs.

I_F

D00D! J00 R0><><04Z!

I'd like to try building a pair of electrostatic drivers, if only for the heck of it. (However, I'm of the "if you're going to do it, do it right" school of thought).

These should produces roughly 3-3.6KV when connected backwards, right? Is this enough for a small electrostatic panel, or would two in paralell or series be needed?

As a side note, I've been looking at amplifiers used with electrostatic panels ;they usually require a transformer to get a +, - and ground for the output. Could I use a bridged amplifier, and the center tap for the connection to the high-voltage power supply?
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Old 29th October 2006, 03:01 PM   #3
v-bro is offline v-bro  Netherlands
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It says it's 30:1, 130V in 3.5V out....
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Old 29th October 2006, 03:32 PM   #4
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Quote:
Originally posted by v-bro
It says it's 30:1, 130V in 3.5V out....

Wire it backwards. 30:1 on 120v (american line voltage) is 3600 volts.
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Old 29th October 2006, 04:26 PM   #5
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Probably a bad idea to wire that xfmr backwards.

The low turns side has a low DCR, which placed across the 120vac line will likely get very hot! .

The best way to get HV is to use a multiplier from a relatively modest starting AC voltage. It's also the easiest by far.

Some mfrs have taken a wallwart style xfmr to dump in a nominal ~12vac, then take a suitable transformer to take the 12vac up to some nominally high AC secondary. Back-to-back xfmrs. The advantage of this scheme is that the first part is almost free, and is low voltage (somewhat safer)... then that higher voltage goes to a multiplier, which is just some diodes and caps...

Also the breakdown voltage of the windings on that toroid is FAR less than the voltage you'd get from a backwards connection.

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Old 30th October 2006, 02:03 AM   #6
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My suggestion was to use these for the audio step-up, not for the bias supply. If you connect a 3V winding to 120VAC the thing will surely burn up.

For audio step-up, connect two 3.5V windings in parallel to your amplifier and connect the two 130V windings in series. The "center-tap" will go to the bias supply, and the other two connections to the stators.

I_F
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Old 30th October 2006, 08:52 PM   #7
v-bro is offline v-bro  Netherlands
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This might work, and you can always parallel the amp-side and place the esl-side in series....

Here they use 100V speaker tranny's (4 tranny's connected 1 side parallel and one side in series)...
http://sound.westhost.com/project1053.htm

This guy uses power supply tranny's too:
..didn't know how they sound till i made me one..
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