PSU noob...

[faton]

Hello,

I am building my first MBsynth and I want to built my own PSU... I have saw on pictures that TK mades his own PSU for his two units 19" rack OPL3 synth...

Where can I find the components list, and a PCB for that 5 v and 12 +/- v PSU?

Thanks

Faton

[nILS]

It's all in the WIKI :D

http://www.midibox.org/dokuwiki/northernlightx?s=psu

http://www.midibox.org/dokuwiki/bipolar_12v_psu?s=psu

[faton]

Thanks ;D

[faton]

I just finished my PSU based on northernlightx shematic. I have +5V, +9V, +12V, but -17V at the 7912 output...

Do you think it can be dangerous to connect the OPL3 on +12/-17 V?

Maybe the regulator is dead?

[stryd_one]

but -17V at the 7912 output...

Sounds like you measured from the +5V line, you should measure from GND to -12V. Could you double check? 

[nILS]

I've had the same problem (-17V at the 7912) with various 7912s from the same manufacturer. Solved the problem by getting different 7912s.

[stryd_one]

Heh, what's a 7912 when a 7912 is not a 7912? a 7917, of course!

Who's the dodgy brand we should avoid, nILS?

[nILS]

Can't check right now, as they are back home. But, they're the ones Conrad sells in their stores :-) I'll check when I get back home next weekend. Um, if I don't post an update here within the next 10 days, could someone remind me, please?

[faton]

Thanks, I will try another brand...  :-\

[AndrewMartens]

I've had issues with 7912s as well.  IIRC the problems I was experiencing were with ST's 79xx regulators.  From a bit of Googling, I believe it had something due to them locking up (?) when there was no current draw on the output.  Supposedly it could be fixed by  adding a resistor to ensure a constant current draw during power-on, but that didn't seem to resolve the issue that I was having, either.  Recently I picked up some 7912s from two other sources... and both of those sent me ST units as well.  ARGH.

I think I'm going to be reduced to using a MAX660 or an SI7661, etc. as a voltage inverter for my bipolar supplies.

[faton]

I have tried again with another 7912 from ST electronic, and now it works fine  ;D

I have my +5, +9, +12, -12 PSU very clean and stable...

Thanks to Northernlight!!