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Switching polarity to load with two transistor circuits

Discussion in 'General Electronics Discussion' started by gooisous, Mar 31, 2017.

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  1. gooisous


    Mar 31, 2017
    Hello, my electronics experience is quite limited.

    I am using a raspberry pi to control a servo - But I am switching it on/of via a transistor, not using pwm. Reason being, pwm is limited to the servo's 90 degrees rotation. I power the servo motor directly to get 360 degrees rotation.

    Problem: To turn the servo the other direction, I need to reverse the polarity.

    Currently I have the following circuit (the lamp is my servo):

    This works fine, but I can only rotate the servo one way when switching gpio to high.

    I am thinking of a way to do the following somehow:
    - duplicate the transistor circuit using another gpio
    - use the same voltage source for the second transistor circuit in reverse - somehow blocking flow with diodes maybe to prevent the short circuit? Only one of the gpio/transistor bases will be on at any point in time.

    I would appreciate any advice.

  2. Tha fios agaibh

    Tha fios agaibh

    Aug 11, 2014
    Google H bridge circuit
  3. gooisous


    Mar 31, 2017
    Last edited: Mar 31, 2017
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