Phototransistor and motor feedback (7/7) - Run full PWM скачать в хорошем качестве

Phototransistor and motor feedback (7/7) - Run full PWM

Modifying the dodgy full PWM idea, by adding op-amps between the filter output and the transistors of the second timer, to act as a buffer and to try and give adjustment to the transistor base drive. Scope probes on the phototransistor output and mosfet gate. First potentiometer shown is for the active filter's timer, used to adjust the roll-off frequency as motor speed selection. The modified circuit of the second timer, used for the PWM signal out to the mosfet, uses the RHS potentiometer to adjust the base drive of the transistor controlling the width of the off state, and LHS pot for the transistor controlling the width of the on state. Initially adjusting the pots to try and get the motor to run slowly without the pulsing. Then seeing how it reacts over the range of the speed selection. Moving the scope probe from the phototransistor output over to the drain of the mosfet. Having a look how noisey the motor is without and with a 1000uf capacitor added. And seeing an improvement to the smoothness of the motor rotation at lower speeds. But still not great for fine motor speed control over a wide speed range.