Source: Dick Ivers
Here is another F1Q timer to put on your list. This timer is fully operational in at least four airplanes right now.
Two servos plus motor speed control. The current software utilizes one servo which moves sequentially under microproccessor control. A slotted servo disc releases levers holding lines for VIT, AR,and DT. Separate VIT and AR release times can be set to occur either before or after motor shut down.
There are two choices. A Palm handheld computer or on-board manual switches. The Palm is used only as a terminal device, so a laptop computer could be used instead so long as it has a serial connection. With a computer interface all timing is set with 0.1 second resolution. The motor speed can also be preset from 0% to 100%. The manual system is less precise, but does not need any computer equipment to be brought to the field.
A push button switch on the airplane sets up the timing sequence. First press: the servo is moved and held at a position to load the release levers. When ready, the button is pressed again and held for 4 seconds to arm the motor and start it running. Finally, the button is released at launch to start the flight timing. The button also functions as an emergency shut down. If you change your mind about launching just press the button again and the motor stops instantly. Also, there is an on-board switch to power the timer on or off.
An on-board beeper sounds if bad inputs are programmed. For example, if DT time is less than motor run time the alarm sounds and motor start is electronically aborted.
Input ports are available for 2 radio inputs: motor shut down and DT.
The timer works in cooperation with a commercial motor controller which is part of the electric drive train. The controller is powered from the motor battery. It sends regulated power to the timer, receives speed control signals back from the timer, then sends drive power to the motor.