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BS2 reset problem (solenoid-related) — Parallax Forums

BS2 reset problem (solenoid-related)

BronsonBronson Posts: 44
edited 2010-10-22 05:49 in BASIC Stamp
Hi,

I am doing a project with BS2 for driving 220V solenoid. I use relay between BS2 & solenoid.
The problem is sometimes my BS2 resets when I switch on/off the 220V solenoid.
The problem only occurs when I connect the solenoid to the relay. BS2 & relay (without solenoid) works perfectly. Based on that, can I assume that the problem is not "relay kick-back" issue?

I am also using ULN to interface between BS2 & relay. To power up BS2, I use switching supply.

Desperately need help.....Any advice?

Thx
Bronson

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-21 10:48
    You've got some kind of electrical noise somehow conducted back from the solenoid to the Stamp's power supply. It might be induced through the wiring or somehow conducted back through your switching supply. You may need some shielding around the power supply, the Stamp, and anything associated with the Stamp. You may need some additional filtering on the output (or input) of your switching supply. You may need some shielding around your wiring. It's impossible to tell without much more detailed information.
  • BronsonBronson Posts: 44
    edited 2010-10-21 11:06
    Mike,
    Thanks for your quick reply.
    In your opinion, is it more likely EMI/RFI problem or "relay kick-back" problem?

    For additional info, at the BS2 board side (at power section), I do exactly like BOARD OF EDUCATION. Do I need to put additional filtering on that? If yes, pls tell me how.

    What about bad ground plane of PCB? Could it be the culprit?

    Thanks
  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-21 11:24
    There are so many possibilities that I'm tempted to just say "Yes". Like I said, you haven't given much detail about how things are connected, how things are mounted, etc. When you're switching 110VAC or 220VAC into an inductive load, there's so much that can happen. If the AC cycle is at peak, you can get a big "kickback". Consider using a SSR (solid state relay) with a zero-crossing detector rather than an electromechanical relay. You'll also avoid the need for a driver transistor. Make sure the 220VAC wiring for the solenoid is routed separately from the wiring to the logic board's power supply.

    The ULN drivers have a built-in "snubber" diode so it's unlikely that you're getting relay "kickback". Also, you're not getting the problem when the solenoid is disconnected.
  • BronsonBronson Posts: 44
    edited 2010-10-21 18:02
    Mike,
    I just did a test to my board. If I turn off the board for approx 0.5sec then turn it on again, BS2 doesn't reset.
    Base on that, can I say that it is not the power supply related-problem?

    Thank,
    Bronson
  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-21 20:26
    You have to provide more information for me to say anything more.
  • TinkersALotTinkersALot Posts: 535
    edited 2010-10-21 20:51
    I have something like this before. The problem was that the current capacity of the supply did not meet the load demands of the switched components and would cause a power sag on the BS2, causing it to reset.
  • BronsonBronson Posts: 44
    edited 2010-10-22 05:49
    Tinkers,
    Thanks for your input. I will pay attention on that

    Regards,
    Bronson
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