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Thursday, August 5, 2010

Power supplies and VCO

Nyle and I had another good discussion about power supplies and he reported the VCO, "is standing tall." He is very happy with it and has the output voltages about the same level. I've made what I hope are the last modifications so I can get some PCBs in production.

Nyle strongly suggested, and I agree with it and have done it on my MOTM and JH VCOs, to put the V/Oct trimmer on the panel or at least front panel accessible. I've used a Vishay-Spectrol adapter which lets you mount a 3/4 inch multiturn trimmer on a panel and the adjust it with a fine screwdriver or a trimmer adjusting tool. the make tuning the V/Oct so much easier. Nyle also suggested losing the "VAR VC" and making the third VC input be some defined fraction (like 1/2) of a volt /per octave. Or, the user could just have 3 matched v/oct inputs. To that end, I've modified the panel and the schematic/PCB to reflect this.

We also discussed power supplied, but no firm decisions were made. We mostly discussed the advantages of making his circuits run on +/- 12 instead of the +12 / -10 they use now. When we figure out what we're doing on that front, I'll post here.


  1. +/-12V would be super.
    That would cover a lot of possible territory (Euro, Serge, etc), and you don't have to fuzz about with regulators and stuff. :-)

    Also, please make sure you have a GND banana socket somewhere available. Like STS does on their PSU blocks.

    Keep going !

  2. I agree. +/- 12 without having to trim a regulator would be ideal. It all came up when Nyle and I were discussing the V/Oct tuning and he said he had to re-tune the prototype I gave him because he was using a +/-12 volt supply. We talked about it and decided we should maybe just make sure they run on +/-12 volts.

    Nyle confirmed there is nothing special with the +12 -10 configuration.

    What or where would you want a GND banana socket? I'm not understanding.

    Thanks! I'm going as fast as time and money will let me :)

    I've got the Gerber files ready to go and as soon as I give them a final look, I'm ordering what I hope will be the production version of these first modules. There are a few comments, like yours, I want to clear up first, too.

  3. You'll need a GND socket when you want this system to interface with another system which doesn't use grounding at its sockets, like Serge, Modcan A and Cynthia.
    Simply connect both GND sockets (pref' w/a banana), resulting in both grounds being "equal", and thusly avoiding hum and other problems.

    Likewise, similar systems (say, different Serge panels powered by separate PSU's) are connected in the same way, so they can 'talk' to each other.

    I'm often surprised most Euro/Frac/etc manuf's don't implement this, because it's easy and doesn't cost more than 70 cents.

    IMHO, this would be a gentle & friendly nod & wink to all those banana-people out there. :-)

    Of course, if this is going to be a DIY system, then those particular folk can take care of themselves easily, and I didn't say anything.

  4. OK, I've got it. To start, this will be a DIY system where I'm going to sell the PCBs I'm laying out and panels if people want them. assembled modules will come later if there is sufficient interest.

    Thanks for the comments.

  5. What about those of us with +/-15v systems (Modcan, MOTM, Blacet, etc.) - will the PCBs just need some part substitutions to work properly?