power supply problem

chopchip · 01:25 AM

can anyone tell me why im not getting 250 votls from the voltage doubling circuit in the bottom right of the diagram? im measuring 60 volts across each capacitor when they should read 120 each i think.

this is a circuit based on an 13em7 tube

thanks

nigelwright7557 · 28th June 2010, 01:37 AM

Measure the voltages on the transformers that might give a clue.

chopchip · 28th June 2010, 01:51 AM

Quote:

Originally Posted by nigelwright7557

Measure the voltages on the transformers that might give a clue.

i get 120 volts after T2

gootee · 28th June 2010, 01:52 AM

You must have D2 connected to the bottom of the transformer instead of the top.

chopchip · 28th June 2010, 01:57 AM

Quote:

Originally Posted by gootee

You must have D2 connected to the bottom of the transformer instead of the top.

there is a bottom and top? but it is ac, i thought it wouldnt make any difference. do you mean the secondary or primary windings?

gootee · 02:05 AM

Quote:

Originally Posted by chopchip

there is a bottom and top? but it is ac, i thought it wouldnt make any difference. do you mean the secondary or primary windings?

On the schematic, D2 should connect to the transformer where D1 does, not on the other end of that winding. Otherwise, the voltage will not be doubled.

chopchip · 28th June 2010, 02:10 AM

Quote:

Originally Posted by gootee

On the schematic, D2 should connect to the transformer where D1 does, not on the other end of that winding. Otherwise, the voltage will not be doubled.

i have it wired exactly like the diagram. maybe i need to sleep on it and take fresh look to-morrow

gootee · 02:48 AM

Are you measuring for DC across C3?

If it's wired correctly and you get about 160 to 180 V DC (or average) across C3 instead of about 330 V DC, then one of D1, D2, C1, or C2 might be shorted.

Actually, if D1 or D2 were shorted, you'd get about 174 volts average (177 V RMS) across C3, but with about 95 volts of 60 Hz AC riding on it.

If C1 or C2 were shorted, you'd get about 165 V DC across C3, with probably about 306 mV of 60 Hz ripple riding on it.

And if everything is OK, you should get a nominal 329 V DC across C3, with about 320 mV of 60 Hz ripple. (Values may be different, depending on load. I assumed you would be pulling about 70 mA from it.)

Cheers,

Tom

chopchip · 28th June 2010, 02:41 AM

im looking at a java voltage doubler demonstration and i dont see a ground connection there. is this a problem?

gootee · 28th June 2010, 02:52 AM

Do you have the ground connected as shown in your schematic?

P.S. You might want to do a CTRL-Refresh, in case you didn't get all of the edits I did on my last message.

28th June 2010, 01:37 AM	#2
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Measure the voltages on the transformers that might give a clue. __________________ http://www.murtonpikesystems.co.uk PCBCAD50 pcb design software.

28th June 2010, 02:29 AM	#8
gootee diyAudio Member Join Date: Nov 2006 Location: Indiana Blog Entries: 1	Are you measuring for DC across C3? If it's wired correctly and you get about 160 to 180 V DC (or average) across C3 instead of about 330 V DC, then one of D1, D2, C1, or C2 might be shorted. Actually, if D1 or D2 were shorted, you'd get about 174 volts average (177 V RMS) across C3, but with about 95 volts of 60 Hz AC riding on it. If C1 or C2 were shorted, you'd get about 165 V DC across C3, with probably about 306 mV of 60 Hz ripple riding on it. And if everything is OK, you should get a nominal 329 V DC across C3, with about 320 mV of 60 Hz ripple. (Values may be different, depending on load. I assumed you would be pulling about 70 mA from it.) Cheers, Tom Last edited by gootee; 28th June 2010 at 02:48 AM.

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28th June 2010, 01:52 AM	#4
gootee diyAudio Member Join Date: Nov 2006 Location: Indiana Blog Entries: 1	You must have D2 connected to the bottom of the transformer instead of the top.

28th June 2010, 02:41 AM	#9
chopchip diyAudio Member Join Date: Feb 2010 Location: calgary alberta tundra canada	im looking at a java voltage doubler demonstration and i dont see a ground connection there. is this a problem?

28th June 2010, 02:52 AM	#10
gootee diyAudio Member Join Date: Nov 2006 Location: Indiana Blog Entries: 1	Do you have the ground connected as shown in your schematic? P.S. You might want to do a CTRL-Refresh, in case you didn't get all of the edits I did on my last message.