PWM motor controller

301

03:31:32

PROTOTYPE

published 4 years ago

mlira

4 years ago

Is the signal at 1.7Hz deliberate? For motor control it's normally around 10-20kHz, which gives you a much smoother output without huge capacitors and long delays as they charge up.

sirendude

4 years ago

I don't know how to use a 555 timer very well so that's why this is a prototype.

mlira

4 years ago

It's really just about charging and discarging the capcitor on the left between 1/3 and 2/3 of your supply voltage. When it hits 2/3 of the supply pin 7 is switched to ground and the capacitor discharges through the resistor between the cap and pin 7 until it reaches 1/3 of the supply, then pin 7 is dissconnected from ground and the cap starts charging again. Whenthe cap is charging the output is high and when it's discharging it' low.

mlira

4 years ago

Your circuit uses diodes (which don't need to be zeners) to force the cap to charge and discharge along different paths. By giving the capacitor diffenent resistors to charge and discharge through, you can change how quickly it charges and diacharges individually (between the 1/3 and 2/3 values). The pot then makes it so if you remove resistance from the charging path (shorter charging) you add it to the discarge path (longer discharging) so the time for a complete cycle stays the same.

mlira

4 years ago

Also just ignore pin 5 unless you need to change the voltage it triggers at.

BillyT

4 years ago

All that mlira says is correct, I have enclose a circuit to show a example of the circuit's possibilities, even though the frequency is limited by the abilities of the simulator. http://everycircuit.com/circuit/5569576672428032

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