hi!

i wanted to control my dc motor speed, so i made an astable multivibrator ( analog cuz i want to learn to do it manually)

this schematic works okey ( the dc motor speed increase and vice versa) and the transistor doesnt get hot so much ( when i prevent with my hand to run to motor forward)

but i have a doubt, is this really a PWM DC Motor Controller? or i just made something else?

link:



http://s18.postimage.org/qtrqro3hl/my_astable_pwm_schematics.jpg

 

Yes, definitely PWM. There are better ways to do this, but I've seen worse!

Next step, replace the two multivibrator transistors with a 555.

It's important that the transistor driving the motor can handle the motor current and that the base current is sufficient to fully switch it on at full motor current. Then it should not get hot.

 

Astable multivibrator is anno tobacco in terms of technology.

It is not guaranteed to start oscillating, or to continue to run, even if these astable MV usually do work.

PWM? I do not think.