S&H: Sample and hold/track and hold (2HP)

A simple (emphasis on simple) sample and hold module

Does what it says on the tin - this module does not contain a free-running clock so will need some sort of external trigger/gate mechanism (eg. envelope generator or LFO will do) in order to work. It'll do both sample and hold and track and hold. 

So what's the difference between sample and hold and track and hold? Basically it depends on what kind of signal you use at the gate/trigger input. A trigger will sample and hold the incoming voltage at the point at which the  trigger goes high and then will be held once it goes low again. A gate will behaving in much the same way, except the signal is tracked for as long as the gate is high and held once it goes low again.

If you want to replicate the stereotypical 'bleepy bloopy' computer sound from the 50s and 60s, you'll need a noise source, a trigger generator and a VCO - run the trigger and noise into the S&H module and pipe the output to a VCO and there's your retro computer noise right there. 

Hold time/acquisition rates are determined by the value of the hold capacitor (the polypropylene cap on the mainboard) and there's a significant trade-off between acquisition speed and voltage droop. By default I use 4.7nF as this has worked well in the past - if you're handy with a soldering iron, you can remove the capacitor and replace it with something different (I'm happy to do this on request, but there would be a modification charge)