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MOS Doubler works... kind of...

5/6/1998 3:02 PM
R.G. MOS Doubler works... kind of...
I proto'ed the MOS Doubler. Worked first time, oddly enough; a sine wave in produces a double-frequency sine wave out, no muss, no fuss. That's almost scary. A couple of observations came out of this.  
 
(1) Damn! Mike Rejsa's modification to the stock proto board to allow you to have a proto board with jacks, controls and a bypass switch is an incredibly good idea. Although I have previously posted the picture of his board, I also took some pictures of mine(never let well enough alone...) and I'll post them on the web site ASAP. Getting a guitar through this thing took 12 minutes from the time I sat down to start plugging in parts. If you mess with effects, you gotta do this.  
 
(2) I first tried discrete MOS devices, reasoning that I could pick devices for best characteristics, and select for matched ones. It turns out that having a matched pair is more important than the exact device characteristics. The CD 4007 two pairs plus inverter is ideal. The matching of monolithic devices overshadows better gain/threshold/etc.  
Out of ten VN10L's I only got one good pair.  
 
I'll try to get the circuit and a PCB on line as soon as possible. I'd like to put PDF style documentation on line for this thing, but I found that apparently you have to pay Adobe's $300 for the Acrobat full version to get PDF Writer.

 
Replies:
anonymous I'd like t... -- 5/6/1998 9:48 PM