tweedclassic
Active member
- Joined
- Nov 22, 2008
- Messages
- 25
i just finished building my power supply for the 12au7 vari-mu pioneered here by PRR.
my problem is i am getting the voltages +,- 20v dc for the opamps (i need +,- 16vdc)
and the heater supply is giving me 20v dc as well(i need 12v dc).
the problem lies in the power transformer i got is a little out of spec and giving me 15.23vac instead of 12 so i am getting 20v dc on the output of the bridge rectifier.
my questing is can i knock the voltage down buy just increasing the 220 ohm resistors in the op amp power supply
and the increasing 16 ohm resistor in the heater supply?
how would i go about calculating larger resistor sizes? (i have no electronic education more or less trial by fire i would say. but would like to know what i am doing)
would i need higher wattage resistors?
here is a link to the schematic and pcb layout i am using.
http://www.diyfactory.com/projects/diy12au7comp/diy12au7comp.htm
Kind regards
Robert
my problem is i am getting the voltages +,- 20v dc for the opamps (i need +,- 16vdc)
and the heater supply is giving me 20v dc as well(i need 12v dc).
the problem lies in the power transformer i got is a little out of spec and giving me 15.23vac instead of 12 so i am getting 20v dc on the output of the bridge rectifier.
my questing is can i knock the voltage down buy just increasing the 220 ohm resistors in the op amp power supply
and the increasing 16 ohm resistor in the heater supply?
how would i go about calculating larger resistor sizes? (i have no electronic education more or less trial by fire i would say. but would like to know what i am doing)
would i need higher wattage resistors?
here is a link to the schematic and pcb layout i am using.
http://www.diyfactory.com/projects/diy12au7comp/diy12au7comp.htm
Kind regards
Robert