how can i make an inexpensive walk around unit for DC control?
MRC made one once for $10. It was rheostat in a box.
CVP makes ‘wireless’ DCC one’s for $150,
One has to duplicate the ‘control’ circuit.
Check TracTronics (http://www.tractronics.com) and look for the Cooler Crawler article, which includes schematics for a transistor walk-around throttle that you can build yourself.
Check www.thegmlenterprises.com for some of the best hand-held throttles built.
I’ve used them for over 20 years with no problems whatsoever.
They start at about $50 bucks and worth every penny.
gtirr
if you are feeling adventurous you could always try http://home.cogeco.ca/~rpaisley4/CircuitIndex.html
a small word of warning though. make them on breadboard first. also most circuits for model railroads require relitivly high current (2 amp) transformers. you can make a much cheaper alternative from a computer power supply. just make sure you put a load resistor across the feed.
Peter