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Old 22nd November 2007, 01:24 AM   #1
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Default Cheap ESL bias supply parts

Resistors are $2.50 each, the inverter is $5. Put a voltage doubler or tripler after the inverter and use a resistors in series to make a good bias supply for an ESL.

5 Meg, 2000V resistor:
http://www.goldmine-elec-products.co...?number=G16413

10 Meg, 2000V resistor:
http://www.goldmine-elec-products.co...?number=G16411

18 Meg, 2000V resistor:
http://www.goldmine-elec-products.co...?number=G16374

5VDC in 1000Vrms out DC to AC inverter:
http://www.goldmine-elec-products.co...?number=G16565

12VDC in, -7.5 kVDC out. Use one of these with a couple resistors to divide the voltage to 5kV or less:
http://www.goldmine-elec-products.co...p?number=G1783

I_F
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Old 22nd November 2007, 09:07 PM   #2
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Default Great Heads Up Post!!!

Thanks for taking the time to post this useful information.
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Old 3rd December 2007, 02:26 PM   #3
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Default Inverted ESL

Hello, All:

I am having a problem with one of my Beveridge ESLs, in that on power-on, one of the transducer diaphragms is drawn to one of the stators. Rick Beveridge says that this is a symptom of old age...reduced tension on the Mylar..., and that the other 5 diaphragms are probably not too far behind. Apparently, the built in OTL amps will (or can) go to full +/- 5kV potential when first turned on, and this will draw a weak diaphragm into one of the stators. When this problem first appeared, the diaphragm would release itself after a second or two, but now it clings to the stator until power is switched off. This is accompanied by a loud "whine" while it occurs...not very musical and perhaps destructive.

In an effort to prolong the life of these expensive to service transducers, I was contemplating converting them to transformer driven electrostats like the Beveridge 3, which uses the same high resistance stator design and the same aluminized Mylar diaphragms. In these speakers, the stators carry the bias charge and the low resistance diaphragms carry the audio signal.

OK, so can you guys help me design a bias supply and recommend a suitably audio transformer? And/or does anyone here have a schematic for the Bev 3's?

BTW, my version is the original full range one and doesn't have the built-in sub crossover.

Thanks in advance,
David
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Old 3rd December 2007, 03:21 PM   #4
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Default Re: Inverted ESL

Quote:
Originally posted by david yost
Hello, All:

I am having a problem with one of my Beveridge ESLs, in that on power-on, one of the transducer diaphragms is drawn to one of the stators. Rick Beveridge says that this is a symptom of old age...reduced tension on the Mylar..., and that the other 5 diaphragms are probably not too far behind. Apparently, the built in OTL amps will (or can) go to full +/- 5kV potential when first turned on, and this will draw a weak diaphragm into one of the stators. When this problem first appeared, the diaphragm would release itself after a second or two, but now it clings to the stator until power is switched off. This is accompanied by a loud "whine" while it occurs...not very musical and perhaps destructive.

In an effort to prolong the life of these expensive to service transducers, I was contemplating converting them to transformer driven electrostats like the Beveridge 3, which uses the same high resistance stator design and the same aluminized Mylar diaphragms. In these speakers, the stators carry the bias charge and the low resistance diaphragms carry the audio signal.

OK, so can you guys help me design a bias supply and recommend a suitably audio transformer? And/or does anyone here have a schematic for the Bev 3's?

BTW, my version is the original full range one and doesn't have the built-in sub crossover.

Thanks in advance,
David
This probably ought to be in its own thread... nevermind, I see it already is...

I_F
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Old 23rd October 2009, 02:31 AM   #5
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5VDC in 1000Vrms out DC to AC inverter:
http://www.goldmine-elec-products.co...?number=G16565


If I use the inverter with 1000Vrms output and feed into the doubler / tripler circuit,should I use a diode with 2000V rating or higher?I am afraid the cheap 1N4007 cannot meet the requirements here.

Thanks.
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Old 23rd October 2009, 02:15 PM   #6
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Audio ESL, I found your link did not work for me. Yes I think you would need a diode with a higher PIV than a 1N4007. It needs to be 1.414 times the RMS ac supply voltage plus a safety margin so you would need to be thinking of a rating around 1.5 to 2KV.

Keith
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Old 23rd October 2009, 02:40 PM   #7
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Quote:
Originally Posted by Keith Taylor View Post
Audio ESL, I found your link did not work for me. Yes I think you would need a diode with a higher PIV than a 1N4007. It needs to be 1.414 times the RMS ac supply voltage plus a safety margin so you would need to be thinking of a rating around 1.5 to 2KV.

Keith
Excuse me,may I confirm one point?
For the diode,the voltage across on it in 1.414 times Vrms,
For the capacitor,the voltage across on it is 2.868 times Vrms.

Thanks!
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Old 15th January 2011, 07:38 PM   #8
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Default Dirt cheap, safe bias supply

Electronic Goldmine has 3VDC in, 2KVDC out modules for $6.

Battery Operated High Voltage Generator-The Electronic Goldmine

All you need is a wall wart and a high voltage resistor to make a small, safe bias supply for your ESL or headphone project.

I_F
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Old 16th January 2011, 01:28 AM   #9
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Neato, bug-zapper HV! My concern would be that this chopper inverter might be radiating power all around at some noxious audio frequency.

A ladder multiplier with maybe 8 steps is about as simple and cheap a HV supply as anyone could wish.

Either way, you start with some kind of power supply into the multiplier section.
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