So I have tech 3 9500 and Control Master 20 MRC transformers 2 of each. I have been using this set up for humm perhaps 20 years every Christmas. Normally for the shows I have 1 or 2 of these transformers set up with the momentum switch turned on and the speed set to where the engine runs OK. They run for a about 6 weeks all day reliably at the Christmas displays with the motion detector turning them on as people are moving in front of the display this keeps the motion detector on and the timer is set to about 1 minute so when they walk away it shuts off after a minute. So it would simple I think to on the Control master 20 to open the hand held remote control and clip one of the wires to the rheostat. Wire this to a relay, when the motion detector turns this on it is like having someone turn the throttle up quickly then when power to relay is cut it is like turning the throttle off and the momentum control will lower the volts slowly. Then I need to find some way to keep the power on on the power pack longer then the relay. Humm perhaps two motion detector circuits???