Need Help with Power Supply

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
User avatar
Deric
Posts: 775
Joined: Sun Jan 14, 2007 2:56 am

Need Help with Power Supply

Post by Deric »

I want to build a 12AU7 powered amp based on this schematic...

http://www.18watt.com/files/18w_au_3_201.jpg

I have a 190-0-190 PT that I'd like to use instead of the voltage doubler shown in the schematic. Since the schematic does not show any voltages I want to simulate the power supply using Duncan's Power Supply Designer.

How do I determine the current draw at each node of the power supply?

EDIT:
I've figured out the current draw for the preamp and phase inverter but I'm still struggling with the draw of the 12AU7 in push-pull. :oops:
Deric®
User avatar
skyboltone
Posts: 2287
Joined: Wed May 10, 2006 7:02 pm
Location: Sparks, NV, where nowhere looks like home.

Re: Need Help with Power Supply

Post by skyboltone »

Deric wrote:I want to build a 12AU7 powered amp based on this schematic...

http://www.18watt.com/files/18w_au_3_201.jpg

I have a 190-0-190 PT that I'd like to use instead of the voltage doubler shown in the schematic. Since the schematic does not show any voltages I want to simulate the power supply using Duncan's Power Supply Designer.

How do I determine the current draw at each node of the power supply?

EDIT:
I've figured out the current draw for the preamp and phase inverter but I'm still struggling with the draw of the 12AU7 in push-pull. :oops:
Figure 20MA there. But you're really pushing that tube. The designed power supply puts out about 240V and you want to throw 370+ at it. It won't work. That transformer costs about $30 from antique electronics supply. Save yourself some headache and get one. If you use a 560ohm bias resistor on your pushpull pair at 375VDC I think you'll bias that thing up at about 50Volts. Then you've got the 470ohnm into the 47K tail in the PI. No good at those voltages.
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
User avatar
Deric
Posts: 775
Joined: Sun Jan 14, 2007 2:56 am

Re: Need Help with Power Supply

Post by Deric »

I was not planning on using a voltage doubler with the PT I have. I was guessing that with full wave diode rectification I would get about 260v with no load.
Deric®
User avatar
skyboltone
Posts: 2287
Joined: Wed May 10, 2006 7:02 pm
Location: Sparks, NV, where nowhere looks like home.

Re: Need Help with Power Supply

Post by skyboltone »

Deric wrote:I was not planning on using a voltage doubler with the PT I have. I was guessing that with full wave diode rectification I would get about 260v with no load.
It was late. Sheesh. How did I come up with that? OK.
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
User avatar
Deric
Posts: 775
Joined: Sun Jan 14, 2007 2:56 am

Re: Need Help with Power Supply

Post by Deric »

Well I feel better now. You had me thinking I was WAY off base there. :shock:

My plan was to simulate the power supply in the schematic to get an idea of the voltage at each node of the power supply. Then, do another simulation with the 190-0-190 PT using diode rectification and see how close they are.

Thanks for the input! 8)
Deric®
Post Reply