Electric bicycle stepless speed regulation circuit with overcurrent protection

In the figure, RC is the compensation network to improve the torque characteristics of the motor. The specific value is determined by experiment.
The circuit is shown in Figure 16-91. It is suitable for electric bicycles or electric tricycles. By adjusting the potentiometer RP,
the square wave duty cycle of the square wave generator composed of the 555 time base integrated circuit A can be changed to achieve the purpose of speed regulation. Rs is the overcurrent sampling
resistor. When the motor is overloaded, the voltage drop on Rs increases, causing the transistor Vtz to conduct, triggering the bidirectional thyristor V to conduct, shunting
part of the load, thereby protecting the power tube VTi.