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Electrical Interference in USB Keyboard

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  • Electrical Interference in USB Keyboard

    I am trying to work out the last major problem in my system, and it is proving to be a pain in the ***. I have used the factory steering wheel audio controls to control a modified Apple USB keyboard. The facotory control had only one wire (a data wire) coming from it, and I needed to control 5 contacts on my keyboard. What we did to make this work was tricky - We used resistors and relays to interface the factory controls to the keyboard. It works well, but of course, there is a problem. Whenever I lock the doors, electrical interference is introduced, causing the keyboard to send a signal to the laptop. This is a major problem for my system, since it wakes from sleep when the external Firewire drive is not powered, causing the system to crash (soundjam is attempting to access the drive). Also, when the engine is being started, commands are sent from the keyboard. The relays are not activated, so my best guess right now is the keybaord itself is receiving the interference. I relise this is most likely a very specific problem with my particular setup, but if anyone has any ideas on how to shield something from this kind of electrical interference, please post a note. Or email me, and I will send you pictures of the hardware in question.

  • #2
    Putting it in a small metal box will usually shield it pretty well... if you have room for a small metal box.



    • #3
      You might want to try installing a noise filter such as a capacitor across the power leads going to the keyboard. Also, you may want to try grounding the keyboard ground at the keyboard PCB to the vehicle's ground (frame, engine block, etc.)

      [This message has been edited by jjohnson (edited 01-22-2001).]
      Jason Johnson
      Yorba Linda, California

      MPC Phase IV - *** PENDING ***