Hi Carter,
2 potential solutions
Solution One
Why not use the brakes to stop the reactor. Just connect the brake light on a relay "normally open" and put a capacitor between the brake light and the relay. The capacitor will give a delay of about 5-6 seconds and avoid unnecessary stops when short braking.
Exemple:
brake, 5-4-3-2-1 -> the reactor stop
Solution two
Use RPM TACHOMETER with ajustable SHIFT LIGHT and a relay "normaly close" at the voltage of the RPM shift light . Set the shift light to the desired RPM. Use the shift light to open the relay and start the reactor.
Ref:
http://cgi.ebay.com/ebaymotors/ws/eB...87949090190346
What do you think?