Modular synth madness

Aaaaaaaaaaaaaaaaand then I built another low frequency oscillator. ;-)

Next on the solder up list, two of these... envelope generators. 

Then work out remaining space and build a low frequency oscillator. Actually, thinking about it, I've got a couple of spare LFO's which need debugging due to them being designed with horrible Soviet era transistors, which I'll replace with Western 2N3904's or 6's. 

Soviet transistors (KT series) are great. They're light and IR sensitive, which is ... interesting... and the pinouts are completely different than Western ones. Oh yes, and they're unreliable. So there's fun.

Envelope generators below - attack, decay, sustain, release. These are easy to build. Actually, I might replace the timing capacitors with tantalum ones - again, old stuff, they're snappier, but if you accidentally reverse the current to them, they quite literally go bang, and they have a definite shelf life. 

Old electrolytic or tantalum capacitors age, they still hold the same amount of charge but the rate at which they fill and discharge changes as they get older. This is why you don't buy an old synth (or any vintage electronics, such as a reel to reel tape recorder) without first thinking "are the electrolytic caps in it going to be shot ? " - as that's (a) money and (b) a risk in desoldering old components and resoldering new ones - you can lift traces and damage PCBs if you do it wrong. 

Had a count up last night - about 9,000 individual components, 25,000 solder joints, I think. It's all going to eventually spill over into a third cabinet, which will be full of more complicated stuff, so it's going to be about 14-15,000 components and 40,000 solder joints. 

"Congratulations, Dr Meacham, you've successfully built an Interociter." 

Believe it or not, it's all fairly straightforward to do. Just fiddly (in the extreme) and time consuming. After all, it's 1970's technology, so there's nothing massively complicated in there. Mistakes can be costly, you spend three weekends building something, miss one bad connection or do something slightly wrong, and fzzzzzt, it cooks when you switch the power on. 

The main expense is power supplies and cases, believe it or not (although I'm not building my own DC supplies and working on building cases) - the rest, in kit form, is relatively cheap. I'm now building from bare PCBs and panels. 

If anyone out there is tempted to build one.... drop me a PM. Drop your bank manager and wife a PM, too. 

Well, I could always make you one - come back in about three years ? ;-))))))

Two more envelope generators to build, that's two cabinets essentially finished. Possibly one more to go. 

Back to the soldering. ;-)