Is it normal that I lose about 11 volts in the pre-regulator ?
I have 23 volt unstabilized and 11,8 volt at the output of the LM317T pre-regulator. I measure 9,2 volt max at the output.
I have 2 x 18V transformer and I need 12 volt output
You will always have 2.5 volts over D44/D45 transistor. The rest will be over the LM317/337. How many volts do you have at the Lm317 input? How much load do you have when you test this?
I have 22,5V into/before the LM317 and 11,9V behind it.
I am using a dac as a load, but I have also used a 68K resistor as a load.
I use Lm431 and a 6,8 v zener at dz1. Everthing as in the BOM with trimmers.
positive and negative regulator behave the same.
What is your voltage at pin 2 and 3 on the opamp? The LED's, are they on? It's not a good idea to just add the trimmers. You must at the same time omit resistors.
I have nowhere read something about omitting resistors. I just followed the BOM and soldered all the resistors and the four trimmers on the PCB. What resistors should I move ?
Leds are shining very bright.
Have you used a BOM for a variant? The everything BOM has optional parts so you must use a BOM for a specific voltage. Right now I have made 15, 22 and 24 volts but more voltages will come. The only difference from the 15 volts BOM is that the reference voltage must be tuned down to 6 volts since the gain is set to 2. I see also that I have some problems with the variant generation. I will look into this. I'll come back with updated documents.
I need +/- 12 volt for the DAC. If I can reach this with the trimmers and with some resistors omitted, this would be fine for me.
I used the new BOB for 12 volt and now everything works.
Good! :-D