Original Royer MXL mod power supply

[sr1200]

I created a power supply (PTP on some perf board) from the original Royer schematic for the 2001 mod. and im getting some high voltages and would like to know 2 things

1) does there have to be load to get proper readings
2) if not, im getting +121.7 v on pin 4 (should be 93-100v) and on pin 5 im getting +40.5 volts (should be 6v)

Any thoughts?

 

[dmp]

For the B+, it is an unregulated powersupply so the output voltage does depend on the load.
If you create a dummy load to represent the mic, you will get a better idea what the B+ will be in use. Perhaps try 100k.

The way the unregulated psu works is the input AC from the transformer is an RMS voltage. This means that the peak voltage is times sqrt(2). So for a 100v rms AC input, the peak voltage is ~141v.
With no load at all, the capacitors will charge up towards this limit.
With a load, you have a voltage drop across the resistors in each PI stage (called this because each CRC looks like Greek PI).

The heater should be regulated if I recall correctly, which means it should be 6.3v under load or unloaded. Also  40.5v should not be possible from 9v AC. I'm guessing here since I don't have the schematic in front of me and do not know what transformer you are using

 

[dmp]

Why a new thread? You are asking about this in the other Royer mic thread as well.

 

[sr1200]

i actually had removed the question from the other thread... since im not doing the big ugly version i didnt want cloud that up being that im not using the PS board that was being offered.  as far as what tx im using its a 41 fk 600 (http://recordinghacks.com/articles/one-tube-microphone-from-berlin/ the one mentioned at the bottom of this article)  i hear what youre saying... unless my meter is on the fritz, its 41 vdc

 

[dmp]

Actually looking at the Royer psu it is unregulated for the heater as well.
The tube draws 150 mA I believe, so use a dummy resistor for the load. 6.3v/.150 A = resistance. Power rating should be greater than 6.3v*0.150A.
(V=IR, P=IV)

 

[sr1200]

Hahaha. This is really funny!  The answer.... Its the same as the meaning of life!

 

[dmp]

Took a minute for me to get that 
FWIW, I used a 50 ohm, 5 watt since it is what I had on hand when I wanted a dummy load for the heater.