Hi,
I have a question Whether It can be possible to control The speed of Rc Car motor using Transistor using PWM in Arduino ?
If So what kind of Transistor.
I had tried wit hobby motor wit a transistor BC 337-40 Its works. but with rc car brushed Motor Doesnt. Any Body Know The reason
Whats the required stall current to run this kind of motor?
I had a RC speed boat, the motor took 26 amps at 7 volts so I used 5 FETs in parallel, fortunately the output from the receiver was PWM. Should have no probs doing PWM from an Arduino
The BC337 has a collector current of 800mA max, seems a bit feeble for an RC motor. Did the transistor ever function again and did you put a diode across the motor.
Suitable FET STP120N4F6 drives straight from the output of the Arduino but at 5V gate voltage it will only drive about 8 to 10 amps so if you want more drive then parallel them up.
Dead_Ard
Thanks for the reply. The Bc transistor does not works again. Below i had attached the circuit. i used the parallel connection motor and diode.
I am using 6v 1200mah external power supply to breadboard.
Could you share your FET circuit. It might help me to control my RC car using PWM .
I read your earlier submission.
Drive the motor from the 7.5 volts with the FETs / transistor to ground. Connect the grounds of the Arduino and the 7.5v supply together, Drive the arduino from the 5volt supply but do not connect this supply to the drive motor. I suggest you throw the BC337s in the bin that motor is way to powerful for that transistor. Without climbing into the loft, I beleive that my power boat motor was the the same one or very similar. I used 5 x C2 nicad batteries to power the boat and they only lasted 20 mins before recharge. They were so heavy they made the boat very low in the water. Good job we have NiMh batteries now. As I said the motor took 26amps at max torque. I used 5 FETs to drive that motor. they were 90mOhms each so gave me 18mOhms when parallel. They only needed a very small heatsink and were driven directly from the ouput of the radio receiver.
Don't be fooled be the Newbie label. I am only new to this forum, I've been an Electrical/Electronic/Control Engineer all my life.
Dead_Ard
The FET circuit is easier than the transistor. Replace the BC337 with the FET (available from RS components 877-2955 £1.56 each but you will have to buy five). The data sheet is also available there online.
The FET is labelled Source, Drain and Gate. The Source takes the place of the Emitter, the Gate takes the place of the Base and the Drain takes the place of the Collector. Then wire the other FETs in parallel with the first FET, Source to Source, Gate to Gate and Drain to Drain. Change the base resistor to 100 Ohm, this is not really needed but will protect the Arduino from high gate capacitance discharge currents. If you do not wire enough FETs in parallel then they may not pass enough current for the load and they won't turn fully 'ON' for the 4.9v Arduino output voltage. Remember each FET can only supply about 9 amps with a gate voltage of 4.9V and I reckon that you are going to need at least 15 amps if not more so parallel three or more FETs (this also reduces the 'ON' resistance and thus the power dissipated and therefore the size of the heatsink. You probably won't need a heatsink.
Dead_Ard
Thank you so much for your detailed explanation.
