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shyam4uall
10-16-2008, 11:02 PM
Guys I want to vary ( or u can say want to decrease) the speed of the motor inside my RC car.The motor used is a DC one( :? i think) as its a low priced RC car.

Would it be require to alter the readymade circuits which are built in receiver?or is it possible to control the speed externally through some other circuits?I wont go with the option of using gears so if possible is there some other way out i.e some sort of circuits(PWM,some IC etc.)

If anyone can give the links to those circuits ...i will be very thankful...

devpriya
10-17-2008, 01:23 PM
Feed the input to the driver circuit from a PWM signal generator circuit. Like use a 555 timer and create a PWM waveform, then give this waveform as a control input to a MOSFET which would be acting like a switch for the power supply of your motor driver circuit.

Other option can be, use a Microcontroller and write a small timer based code to generate one such signal and feed it again to the MOSFET.

Hope this answers your question :-)

shyam4uall
10-17-2008, 01:52 PM
Can u please elaborate your answer a little bit more?

What do you mean by the driver circuit ?i'm a bit confused :?

The receiver circuit inside the car gets the power supply from the battery so where i have to connect the PWM generator(using 555).

The receiver ckt is on a PCB(as it is said i guess) so i don't think i can modify any of those items on it.

devpriya
10-17-2008, 02:27 PM
Put a MOSFET b/w the Power Supply and the PCB and control it using a microcontroller or a timer cricuit. Thus you would be switching ON/OFF your circuit as per the waveform and that is what PWM means.

ashish_agarwal123456
10-17-2008, 04:05 PM
if you want to decrease the speed permanently and do not want to vary it at runtime, then just put resistance between power supply and motor. but this will also decrease the torque.... so check your requirements...

a7400
10-17-2008, 04:59 PM
you can vary the speed using PWM technique. check the following tutorial
http://www.triindia.co.in/resources/?p=43

shyam4uall
10-17-2008, 10:09 PM
Thanks..to all


Put a MOSFET b/w the Power Supply and the PCB and control it using a microcontroller or a timer cricuit. Thus you would be switching ON/OFF your circuit as per the waveform and that is what PWM means.

will try and post the experience and also whether it worked or not...