Hi there
I'm new to the site and building circuits
I've completed building a PWM Controller , I'm getting square wave out of the pin 3 from my 555 timers and the motor is spinning but the 10k pot isn't varying the speed of the motor this is my only issue , and I'm unsure how to resolve it
Any help would be great
Thank you !
Welcome here.
I think you have somethign wrong around U1, double check all your connections on this chip.
If you know you have a square wave then I assume you have access to a 'scope, if so check the o/p of U1, its pulse width should change as you vary the pot, speaking of which the wires to the pot should be connected to one of the outer pins and the centre.
Thanks for the advice , I'll test output of U1 tomorrow .
If the pulse width doesn't change what can I look to do to resolve this situation
Also the pot is the connected with one outside and inside terminal .. the final terminal is left untouched
Welcome here.
I think you have somethign wrong around U1, double check all your connections on this chip.
If you know you have a square wave then I assume you have access to a 'scope, if so check the o/p of U1, its pulse width should change as you vary the pot, speaking of which the wires to the pot should be connected to one of the outer pins and the centre.
Driving a motor via PWM isn't linear.... The PWM on the second 555 cannot be a smaller ratio than the pulse from the first 555 so try and make the generated pulse as small as possible...
I think that the pulse is big enough to give nearly full speed so the control is not available.
Try and change the 420 ohm with a 100 ohm and see if you get more control.. As a plan B... Use Alex's PWM here
Driving a motor via PWM isn't linear.... The PWM on the second 555 cannot be a smaller ratio than the pulse from the first 555 so try and make the generated pulse as small as possible...
I think that the pulse is big enough to give nearly full speed so the control is not available.
Try and change the 420 ohm with a 100 ohm and see if you get more control.. As a plan B... Use Alex's PWM here
Basically, the way to look at the 1k on the base of the output transistor is this:
The transistor will divide the resistance of the base resistor by 100 (the gain of the transistor) and the transistor can be replaced by a 10 ohm resistor. Do you want a 10 ohm resistor in series with the motor?????
You can get a much simpler PWM circuit using one 555.