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SEM +/-15v Secondary Power

+/-15v Aux Power Board

+/-15v Aux Power Board

My plans for the modifications to my SEMs require the addition of two pcbs.  One is the dual waveshaper board that will add sine and triangle output waves for the two SEM oscillators and the second is a CV processing voltage board that adds 8 inverting/attenuating controls as well as a pair of inverters for the envelopes to add negative going envelopes to the SEM.  I already have a 5u modular system and so all my DIY stuff is designed to run on+/-15v and tapping off the SEM after the power regulation to use its regulated +/-15v seemed more than a little inelegant even by my standards.  I really didn’t want to redesign the boards (although I had to call in massive help on the waveshapers – more on that later) so I decided to add a +/-15v regulator board to provide me the necessary power for the auxillary boards.

One thing about me that is fairly constant is that I’m willing to spend extra cash on a project if it is going to either save me time or likely be of higher quality.   This is true because if you are getting into DIY, it isn’t going to save you anything over purchasing a unit where economies of scale come into play.  A quick look through the Mouser, Digikey, Newark catalog should make it painfully obvious how these companies do not exist to service the likes of you and me where standard pricebreaks beigin in the 1,000s of peices.  Additionally, I despise  working or any kind of strip/proto board.  For my power needs, I noticed that Ken Stone has a power supply board , the CGS66, designed to use an AC wallwart at 18v AC and deliver regulated +/- 15v DC.  I ordered four of the boards and built them minus the AC filter stage so they really are just 15v regulators with standard amp type connectors for the remaining modules.  The SEM in my casework leaves enough room that these boards are mounted to the back panel.  You can see the parts I left of for the AC filtering in the photo on the right.  Works great and now I have power for the other boards.

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