TWO DC MOTORS ARDUINO REVERSE DRIVERS
Unlike many commercial motor drivers - this driver does not have any "protection" - so if you abuse it too much - it will fail. It's rated at 130% of nominal - or 15.6v. The relay's coil seems to dictate the maximum voltage this circuit can handle. If you're having problems with the controller refusing to reverse - it may be that your input voltage is too low. We'll go through all the connections one-by-one. This is listed as 9.6v - but I've found it to function properly as low as about 7.5v.ĭon't worry if the schematic doesn't make total sense. The minimum voltage to drive this circuit is determined by the "pickup" voltage of the relay. The enable pin may be switched on and off very quickly for PWM (pulse width modulation) speed control.īoth control pins are connected to the microcontroller via 220 Ohm resistors to limit current. The "Base" of the second TIP120 is the "Enable Pin" - turning it on causes the motor to actually run. This is used to turn the motor on and off. The "Base" of the first TIP120 is the "Direction Pin" - turning it on and off switches the direction of the motor.Ī second TIP120 switches power to common on the relay. Since the microcontroller can't quite produce enough current to drive the relay - a transistor (TIP120) is used to switch it on and off. This in effect reverses the wiring whenever the relay is turned on or off. The motor is connected to both normally closed and normally open (in reverse) sides of the relay. This circuit uses a DPDT (Double Pole Double Throw) relay to switch which direction the motor is turning.
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