remote control for a 3V motor

[davidbenjamindix]

I purchased an infrared emitter and detector (radio shack model # 276-0142), and trying to build a remote control button/switch that powers a 3V DC motor (range 1.5-3V). the problem is that the emitter to collector is 5V. Do i need a transistor for the detector? I also want the motor to be 'timed' so it only runs for a short period of time, and possibly have an adjustment on the timer. also, i wonder if 4.5V would be enough power to sent a signal from the emitter to collector? im not too sure how to build the circuit board.

 

[cdh7]

Hi,

Yes, you will need a transistor in the receiver because the phototransistor you specified can only handle 25 mA (and your motor presumably needs more current than that).

In order to time the motor, the easiest way is with a 555. Your phototransistor can be used directly to trigger the timer. Then just hang a transistor on the timer output to turn the motor on and off.

Note that the 555 needs 5V compared to your 3V motor, so you will have to use separate supplies or operate the transistor in its linear mode to keep the motor voltage at an acceptable level.

Regards,
Chris