is this schematic okei?

Discussion in 'General Electronics Chat' started by leonheard, Mar 12, 2013.

  1. leonheard

    Thread Starter Member

    Jan 8, 2013

    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?

  2. JDT

    Well-Known Member

    Feb 12, 2009
    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.
    leonheard likes this.
  3. takao21203

    Distinguished Member

    Apr 28, 2012
    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.