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Whats the best way to send a signal down 60' of wire? — Parallax Forums

Whats the best way to send a signal down 60' of wire?

GICU812GICU812 Posts: 289
edited 2008-10-16 12:30 in General Discussion
I have a device, it has 2 pins, and 2 signals (its a garage door opener for what its worth.

There is approxamately 16 volts when the circuit is working, but if you remove the switch module, its 22v, so I need to be able to cope with up to 25v

From taking apart the switch, Ive determined how it sees the diffrent signals.

Signal A: Short pin 1 to pin 2
Signal B: Connect pin 1 and 2 with a 1uf cap

I have a BS2 about 60' (by the wire) away. What is the best way to send a signal?
I was thinking of having 2 relays at the opener, one for each signal, then two PNP transistors to fire the relays.

I guess my question is, where should I have the transistors, at the opener, or at the stamp?

It would be one less wire to use if I had them at the stamp, and I think the stronger 12 volt signal (relay activation signal) would travel better than the 5v logic signal.

Or am I going about this all wrong with relays, would you reccomed just using transistors instead?

Im assuming the 1uf cap just allows power to flow for a brief instant, so could I just use one relay\circuit and pulse it briefly to immitate that, or am I thinking wrong?



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Comments

  • Lab RatLab Rat Posts: 289
    edited 2008-10-16 10:12
    i would imagine shielded cable

    or twisted pair but i think twisted pair works the best

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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2008-10-16 12:30
    I would say a twisted pair with RS-422/485 drivers, but RS-232 will work on 60' at slower baud rates. The main thing about RS-422/485 is that the driver transcievers are easier to wire than a MAX232 chip and run a lot cleaner data stream if you are actually sending data.

    If you just want to toggle a 25v line on and off, that is a different animal. To handle the 25V at the end of the line, use a rely to isolate it from your microprocessor. Relays always isolate a jump in voltage or a change from DC to AC, so they certainly are a good choice. Transistors or optoisolators may seem more 'high tech', but at times they just don't work at well.

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