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Thread: Relays, Voltage Output

  1. #1
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    Relays, Voltage Output

    I'm a computer guy, but not much for electrical engineering. Just had a quick question about 12v 30a SPDT relays, would 5v across the pole be enough to flip it? Working on a rfid starter system and my board is only putting out 5v atm.

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    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by noctorum View Post
    I'm a computer guy, but not much for electrical engineering. Just had a quick question about 12v 30a SPDT relays, would 5v across the pole be enough to flip it? Working on a rfid starter system and my board is only putting out 5v atm.
    I would just use a transistor to put out 12v when 5v is applied, and send its output to the relay.

    if your relay is 12v, 5v wont be enough.
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    Quote Originally Posted by 2k1Toaster View Post
    I would just use a transistor to put out 12v when 5v is applied, and send its output to the relay.

    if your relay is 12v, 5v wont be enough.
    Alright, thanks for the info. I wasn't sure if 12v meant maximum through the throw or to switch it.

  4. #4
    Constant Bitrate kibble's Avatar
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    Most relays should have a marking where the first part would say something like 12V DC. That would be the voltage to make it operate. The rest would be the voltages and max currents that it could switch.

    If the relay is for cars, then it's definitely 12V.

  5. #5
    Variable Bitrate FPeter's Avatar
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    i made a quick example about connecting safely to any output - general TO92 NPN transistors are able to handle up to 100mA, so most of small relays are ok to use with it...

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