A POSSIBLE 10 TO 30 SECOND ELECTRIC FLIGHT TIMER CIRCUIT for free flight model aircraft.
Inspiration for this circuit design came from Ian Kirkpatrick (see page 23 of the Norcim website). The model electric flight motor is connected to the Lipo 2C battery via the circuit with the switch in the off position. At the point of ‘switch on’ the flight motor will run for a time depending on the position of the variable resistor setting. This should be between ten and thirty seconds.
FLIGHT TIMER CIRCUIT LTspice SIMULATIONS
<< PROTOTYPE USING STRIPBOARD
The circuit gives instant motor at ‘switch on’ with a ‘soft’ switch off of around 1>2 seconds which will help prevent a stall. Increasing C2 would make the switch off softer. Assembly using strip-board. Note if R4 = 100R will give 0 to 30 seconds motor run. The circuit also works well using a single cell Lipo battery. The timings appear to be the same.
The large UK following of Free Fight Model Aircraft can be seen at. http://www.sam1066.org/