I need reversable DC pulse electro magnet driver

Discussion in 'The Projects Forum' started by anthonydomingo, Aug 29, 2011.

  1. anthonydomingo

    Thread Starter New Member

    Aug 29, 2011
    I am looking for a low part count solution that when you Press the momentary push button switch a home built electro-magnet will be first sent a negative voltage then positive voltage with independently adjustable durations from 50 ms – 400 ms. I have been looking at DC motor control IC's but i might be over thinking this. the magnet is under 1.5 amps at 12 VDC.

    Button Push->Negative pulse->Positive Pulse->OFF

    Any ideas?
    Your help is greatly appreciated.

  2. ian123


    Aug 24, 2011
    this can be done with a 555 timer ic there are many circuits available on the net
  3. ian123


    Aug 24, 2011
    or pretty easily accomplished with a pic microcontroller
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
    I attached a circuit with 2x555s (or 1x556), if you could use a uC it will of course give you a much lower part count.

    The outputs of the two 555s go to the H-bridge drivers.
    The first 555 is triggered by the switch, the second 555 by the end of the first pulse.The best would be to drive four individual gate drives for four n-Mosfets. Each 555 output drives an upper and a lower transistor, on opposite sides of the fullbridge.

    edit: bypass caps and switch debouncing circuit are missing in this schematic.
    Also, in your case it may be sufficient to use a H-bridge with 2 high-side p-FETs and 2 low-side n-FETs. Joining the 2 gates of each leg and driving each leg from one 555 output should also work.
    Last edited: Aug 30, 2011