Andrew Davie wrote: Before I embark on motor control experimentation (really, I want anything that will work), I though I'd ask for opinions.
I've not built any of the suggested club circuits - but the particular one you show does seem to be a popular club solution and it certainly does have the merrit of having built in synchronisation (assuming of course you have the sync seperated out already).
Personally I just started with a low value potentiometer (though these can more than a bit hot!) - and rapidly moved on to the following circuit:
http://www.electronics-lab.com/projects ... light/038/
I modified it slightly to use both coarse and fine value potentiometers to give better control. Having said that - the circuit isn't that stable so I doubt I'll build another one like this.
One tip I picked up from the clubshop was to try the LM317 variable voltage regulator. So far I've built a general bench variable regulator which is useful for all sorts of things as well as controlling motor speed. I'm going to build another one with both coarse and fine value potentiometers to give better control specifically for NBTVA use.
The LM317 is cheap and amazingly easy to use - but does (in my opinion) require a small heatsink - even to drive a 200ma cassette motor like I use.
Roland.