Reversing polarity (not for a motor)

Discussion in 'The Projects Forum' started by ppenumbra, Jun 16, 2013.

  1. ppenumbra

    Thread Starter New Member

    Jun 16, 2013

    I'm fairly new to electronics - software engineer by trade. I get the basic parts, but have no experience with circuit design or such.

    I picked up a neat WWII era wind speed and direction gauge set with the intention of wiring it to Internet buoy data with an Arduino. The wind speed was easy to manage using PWM. The wind direction gauge is pretty interesting. It uses 3 electromagnets to move the needle. Each magnet corresponds to a pin on the back of the gauge - A, B and C. Each pin has three states, positive, negative and disconnected.

    I documented the settings for the gauge and researched what I thought to be the best way to wire it up. It seems to reverse the polarity, an H bridge is the most popular method for motors. I "designed" (using the term loosely) a basic H bridge with 3 legs to support my idea.

    To prove it out, I made the first two legs and kept the C pin as negative. It all seemed to work properly. However, today I added the gates for the C pin and everything has gone haywire. I keep getting a short circuit somewhere (USB warnings on my laptop of power usage, strange results indicating stray voltage on the gauge, etc.).

    I was hoping someone could have a look at my circuit and suggest whether I've messed up my breadboard or the circuit design. The Arduino seems to perform correctly, as does the gauge.

    Here's a poorly drawn diagram. Any suggestions, tips or thoughts would be greatly appreciated.

  2. wayneh


    Sep 9, 2010
    Here's the circuit.

    Metalmann likes this.
  3. sq-aristo

    New Member

    Jun 1, 2013
    Is there a common wire of any kind to the gauge? To me it looks like you have to have at least one magnet positive and one negative or no current will flow