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Proximity of AC coil to snubber network

Discussion in 'Electronic Design' started by Jon Danniken, Jan 30, 2011.

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  1. Jon Danniken

    Jon Danniken Guest

    I have a contactor with an AC coil, controlled by a small SPDT relay, and I
    have the need for a snubber to reduce kickback when the relay opens.

    It would greatly simplify things if I were able to mount the snubber network
    on the board with the relay, which is a few feet from the AC coil on the

    I do realize that having the snubber network seperated from the AC coil by a
    few feet is going to have the wires acting as little antennae, but for the
    purposes of protecting the contacts on the little relay, will it be fine?


  2. Jamie

    Jamie Guest

    That snubber will do it's job fine there. If you're worried about noise
    then use a twisted pair to drive the coil. If the snubber is properly
    sized, it should do well in reducing RF radiation. Some use a shielded
    pair with the shield connected only at the driver end to ground.

  3. Jon Danniken

    Jon Danniken Guest

    Nice, thanks Jamie. I hadn't thought about using twisted or coax, but
    that's a perfect idea to reduce any emissions that might want to propagate.

  4. legg

    legg Guest

    Actually, it will be most effective at the breaking-contact location.

  5. Jon Danniken

    Jon Danniken Guest

    Cool, even better! Now that I think about it, that would explain why
    snubbers get mounted on silicon power devices instead of the transformers
    which they control.

  6. Jamie

    Jamie Guest

    Oh really. Think about that for a moment.

  7. Jamie

    Jamie Guest

    Really,, You've never heard of shielded grounds?

  8. Jamie

    Jamie Guest

    Come on John, I know you have it in you!

  9. Rich Grise

    Rich Grise Guest

    No. What's a shielded ground?[/QUOTE]

    I've heard of grounded shields. ;-)

  10. Guest

    That's not true. Of the major pro audio intercom standards, one of three is
    balanced. Even with the one that is, there is no guarantee that there isn't
    several volts between systems.
    But things can sure get hot!
  11. Jamie

    Jamie Guest

    I find it hard to believe to that none has ever used coax or the
    like cable as a ground leg.

    The end that is attached to the ground source has both the shield
    and center conductor combined. On the other end for the device that
    wants the ground with out the noise with it, you use only the center
    conductor and tape off the shield as close to the device as possible.

    In the past, I've used RG8/213 type cable from a good out side ground
    source, and led them up to the entrances of the shack/house with a metal
    plate that had a coax female connector on it where we would attach this
    coax. On the inside, you simply use the center conductor only..

    This same is done noisy environments to reduce noise from traveling
    along the ground legs and along the shielded signal wires.

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