DC brush motor drive circuit using LM339 chip

DC brush motor drive circuit using LM339 chip

The DC brush motor drive
    circuit shows the circuit schematic diagram of the DC brush motor drive circuit using the LM339 chip . LM339 is internally composed of four voltage comparators.     ①Power supply circuit.     The 36V output voltage of the battery is directly added to the power supply terminal of the motor. At the same time, after the voltage is stabilized by the three-terminal voltage regulator ICl 7812, its ③ pin outputs a +12 V voltage. This voltage is filtered by the capacitors C6 and C5 and becomes the motor's voltage. The excitation amplifier and control integrated circuit IC2 (LM339) are powered. At the same time, this voltage is also sent to the ③ pin of the three-terminal regulator IC3 78L06, and its ① pin outputs a +5 V DC voltage.     Ten 5 V voltage provides operating voltage for components such as brake handles and speed control knobs.     @Start the circuit.     Electric auto. When driving and turning on the power supply, the +12 V voltage is sent to the @ pin of IC2A to provide it with the basic working voltage. The IC2A and IC2B parts of IC2 constitute a PWM signal modulation and sawtooth wave signal generation circuit. The @ pin outputs the PWM signal. The amplifier circuit composed of VT1 and VT2 outputs the amplified control signal to drive the field effect transistors VT3 and VT4 to conduct. At this time, the battery, motor, VT3, VT4, and resistor R18 form a loop, and the motor starts to rotate.     ⑤Brake circuit.     The braking circuit of this circuit is mainly composed of the brake switch, VD1 and IC2 internal circuits. When the brake handle is pinched, the normally open, closed, and conductive parts of the brake handle are turned on. The voltage at the IC2A@ pin is connected to ground through VD1 and the gate switch. At this time, the IC2A@ pin becomes low level. This low level signal turns off VT1 and VI2, which also turns off the field effect transistors VT3 and VT4, and the motor is powered off. Stalled.