"Larry Jaques" wrote in message
...
...
Air dream: I'd love to build a small electric car or motorcycle for
kicks.


I had my fun with those, building prototypes at Segway. The machine
itself wasn't as big a challenge as monitoring, logging and analyzing
its performance and changing the controller parameters as needed.
That's what set me looking to buy or build my own low cost, high
resolution portable datalogger, first a microcontroller-based one with
a troublesome common ground and then separate optically isolated DVMs.

A compact Campbell Scientific datalogger was hard enough to mount
securely on a motorcycle, a laptop would be quite a challenge. Laptops
are a great solution on machines that carry a passenger, they were the
original control and display terminals for prototypes of this:
http://www.freeflightsystems.com/products/ads-b

At the same time I was adding a hydraulic bucket loader to my garden
tractor. Hydraulics took more machining to implement but were easier
to debug. The pump puts out a constant flow volume per turn so I only
needed to control engine speed and watch pressure and lifting force,
both easy static measurements. I made a knob-adjustable pressure
relief to replace the fixed one on the control valve assembly and run
it as low as will do the job. The valves are open in the center
position and the fluid just circulates freely with only frictional
losses.

The controls for electric wheelchairs would be excellent for a
homebrew vehicle although I wouldn't divert them from the grey market
for non-subsidized repairs.

-jsw