faton Posted February 23, 2008 Posted February 23, 2008 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?ThanksFaton
nILS Posted February 23, 2008 Posted February 23, 2008 It's all in the WIKI :Dhttp://www.midibox.org/dokuwiki/northernlightx?s=psuhttp://www.midibox.org/dokuwiki/bipolar_12v_psu?s=psu
faton Posted May 4, 2008 Author Posted May 4, 2008 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 Posted May 4, 2008 Posted May 4, 2008 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 Posted May 4, 2008 Posted May 4, 2008 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 Posted May 5, 2008 Posted May 5, 2008 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 Posted May 5, 2008 Posted May 5, 2008 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?
AndrewMartens Posted May 5, 2008 Posted May 5, 2008 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 Posted May 16, 2008 Author Posted May 16, 2008 I have tried again with another 7912 from ST electronic, and now it works fine ;DI have my +5, +9, +12, -12 PSU very clean and stable...Thanks to Northernlight!!
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