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Switching problem — Parallax Forums

Switching problem

Brian MillerBrian Miller Posts: 25
edited 2004-08-12 14:38 in BASIC Stamp

I'm getting ready to start ordering some Stamp boards and chips. I keep reef (saltwater) tanks and have a large central filtration room in my basement for the 400+ gallons of water. I would like to use the stamp as a automation controller to turn pumps and lights on off. I also what to add in some safety float switches to monitor water levels in various tanks.

I have been thinking about using relays but I have concerns about the coils in the relays being energized all the time. The main system pump runs 24/7 but I would like to be able to turn it off via the controller. I don't want to use a normal closed relay because I want the chip to instruct the pump on in the event of a power down and up again.

So I guess my question is... Is there a device that acts like a relay but is more of a toggle switch? Thinking I could send a signal to turn it on and another to turn it off?

Thanks

Comments

  • NewzedNewzed Posts: 2,503
    edited 2004-08-12 13:49
    If you stop to think about it, a DPDT relay is really a toggle switch.· Use a PC board relay to control a contactor .



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    Sid Weaver
    USB-powered Stamp Board

    http://hometown.aol.com/newzed/index.html
    ·
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-08-12 13:52
    You can get latching relays, but they come with their own set of complications.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • AlWilliamsAWCAlWilliamsAWC Posts: 135
    edited 2004-08-12 13:52
    What you want is called a latching relay. I'm sure they are still around. However, this will keep the relay in its last state in event of a power failure (I think).·Keeping the relays energized should not be a big deal unless you are worried about power consumption.

    Regards,

    Al Williams
    AWC
    Basic Stamp FAQ
    http://www.wd5gnr.com/stampfaq.htm
    ·
  • AlWilliamsAWCAlWilliamsAWC Posts: 135
    edited 2004-08-12 13:52
    Woo hoo Jon! You are a little faster than I am this morning smile.gif
  • Brian MillerBrian Miller Posts: 25
    edited 2004-08-12 14:01
    Damn, I love message boards!!! Thanks guys.

    That is what I needed "latching relays" I knew they existed just didn't know what to call them.

    In the event of a power failure I plan on having a·battery backup running so I can start a controlled shutdown. So I should have plenty of time to switch my "latching relays" smilewinkgrin.gif back to where they should be.

    Thanks for the help guys.
  • AlWilliamsAWCAlWilliamsAWC Posts: 135
    edited 2004-08-12 14:07
    Consider getting another pair of contacts or having a logic level the Stamp can sense so you can figure out which way the relay is set when the Stamp resets.
  • Brian MillerBrian Miller Posts: 25
    edited 2004-08-12 14:38
    Thats a good idea. Thanks.

    I can't wait to order my stuff tomorrow.

    ·
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