High Voltage Bias for DIY Electrostatics - Page 4

Ulf Eliasson · 27th February 2010, 02:07 PM

More on safety
You do not normally use transformers to limit current. They have limitations of cause, but in this case it is important to design your high voltage supply to limit current to below a couple of mA to avoid risk of eclectic shock. I use 500kΩ to connect the audio transformers (limits to 0.5mA) and 10MΩ to the membranes.

Running backwards
Running a power transformer backwards is not a good idea if you plan to connect it to the mains. The coil on the secondary side is designed for low voltage and relatively high current, for example 12V 5A (=60VA). If you connect this side (designed to be a source of energy with low inner serial impedance) to the mains (240Vac) you will likely have a short lived smoky 1000W electric fire.

geraldfryjr · 11th March 2010, 06:35 AM

This last weekend I designed a variable bais supply.
Not sure on the maxium output voltage as i haven't built a resistor divider to measure with yet.
It does 0 to 2kv at least and can do more by adding more stages.
It really works as I accidently found out today.
It's really simple and a fairly safe swiitcher that runs off of a 16vdc supply.
The best part is it is 0 to (v)kv variable in order to get the highest voltage possible before arcing.
I will post the schematic as soon as I get it drawn up in circuitmaker. jer

Ulf Eliasson · 12th March 2010, 11:28 PM

Have you tried to disconnect the high voltage supply from the outlet while listening?
Can you observe any change (before the discharge takes its toll of cause)?

kavermei · 15th March 2010, 02:03 PM

Quote:

Originally Posted by Ulf Eliasson

Have you tried to disconnect the high voltage supply from the outlet while listening?
Can you observe any change (before the discharge takes its toll of cause)?

Speaking for myself, I can't. I use a very large series resistor (400 Mohm), forming a ~1Hz lowpass together with my panel capacitance. No issues of hum etc.

Once the diaphragm is charged, the HV supply delivers mere nano-amps.

Kenneth

DUG · 20th March 2010, 11:20 PM

You can use a transformer to step up but operate the winding at the value it was designed for:

use one transformer to step 110 down to 24 (or other available value) THEN step the 24 v up to 110 (or 220) for voltage multiplication

This is not a new idea...VTVM supply used this for filament and 170VDC from two common transformers (110V:6.3V)...more than 40 years ago

isolation and 110 (or 220) AC

Another idea would be a voltage sense transformer 575V:110V. use that backwards for 110V:575V

20th March 2010, 11:20 PM	#35
DUG diyAudio Member Join Date: Jan 2003 Location: mississauga ontario canada	You can use a transformer to step up but operate the winding at the value it was designed for: use one transformer to step 110 down to 24 (or other available value) THEN step the 24 v up to 110 (or 220) for voltage multiplication This is not a new idea...VTVM supply used this for filament and 170VDC from two common transformers (110V:6.3V)...more than 40 years ago isolation and 110 (or 220) AC Another idea would be a voltage sense transformer 575V:110V. use that backwards for 110V:575V __________________ Doug We are all learning...we can all help

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
High voltage, high current super regulator, possible group buy	peranders	Group Buys	54	2nd June 2009 10:43 AM
Wanted - High Power, High Voltage, Audio Frequency Transformer Manual.	kimbal	Tubes / Valves	4	11th May 2009 09:05 PM
bias voltage vs bias current	woodturner-fran	Tubes / Valves	3	25th February 2007 12:24 AM
Could someone explain the ESL High Voltage DC bias supply to me?	jzh797s	Planars & Exotics	4	25th August 2006 04:19 AM
6BY5 High Voltage & High Current Choke Input Design P.S.	snoopyma	Tubes / Valves	7	28th June 2006 02:32 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

27th February 2010, 02:07 PM	#31
Ulf Eliasson diyAudio Member Join Date: Oct 2003 Location: South Sweden	More on safety You do not normally use transformers to limit current. They have limitations of cause, but in this case it is important to design your high voltage supply to limit current to below a couple of mA to avoid risk of eclectic shock. I use 500kΩ to connect the audio transformers (limits to 0.5mA) and 10MΩ to the membranes. Running backwards Running a power transformer backwards is not a good idea if you plan to connect it to the mains. The coil on the secondary side is designed for low voltage and relatively high current, for example 12V 5A (=60VA). If you connect this side (designed to be a source of energy with low inner serial impedance) to the mains (240Vac) you will likely have a short lived smoky 1000W electric fire.

11th March 2010, 06:35 AM	#32
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	This last weekend I designed a variable bais supply. Not sure on the maxium output voltage as i haven't built a resistor divider to measure with yet. It does 0 to 2kv at least and can do more by adding more stages. It really works as I accidently found out today. It's really simple and a fairly safe swiitcher that runs off of a 16vdc supply. The best part is it is 0 to (v)kv variable in order to get the highest voltage possible before arcing. I will post the schematic as soon as I get it drawn up in circuitmaker. jer

12th March 2010, 11:28 PM	#33
Ulf Eliasson diyAudio Member Join Date: Oct 2003 Location: South Sweden	Have you tried to disconnect the high voltage supply from the outlet while listening? Can you observe any change (before the discharge takes its toll of cause)?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)