Newbie question about relay coil voltage
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  1. #1
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    Default Newbie question about relay coil voltage

    I have a small cnc router and I want to use relays to turn on the spindle and dust collector, both 120v motors. The power supply in my router has both 36v and 5v dc outputs. I'm wondering if there's any reason to use a relay with 5v or 36v coil?

    The router draws 7 amps, the collector 11amps. DC output to the relay is 1 amp.

    I appreciate any advice or information, I hate being so ignorant, how does an old fart learn this stuff?

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    How are you going to control the relays?

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    Quote Originally Posted by Yan Wo View Post
    How are you going to control the relays?

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    Quote Originally Posted by Yan Wo View Post
    How are you going to control the relays?
    My cnc controller is Mach3 software on a Windows computer, out-putting to a Gecko G540 4-axis stepper drive, which has 2 auxiliary outputs to control relays. I can use either voltage from the power supply for the relays.

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    Quote Originally Posted by richard newman View Post
    My cnc controller is Mach3 software on a Windows computer, out-putting to a Gecko G540 4-axis stepper drive, which has 2 auxiliary outputs to control relays. I can use either voltage from the power supply for the relays.
    I'd go with 36 volt. But check with Gecko to see if you need snubbers across the coils. Or post a schematic of the output circuit, if it's available.

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    Thank you. I've read that the Gecko doesn't require snubbers across the coils, I think it's handled by the device itself, but I'll check for sure.

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    I think you'll find 36VDC relays are not as easy to find as 5V, 12V or 24VDC relays.

    If it was me, I'd add a 24VDC supply and use 24V relays.

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    24 and 12 volt are common.

    You could get one of each connect in series and make the 36 volts.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

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    Looks to me 36 volt coil relays are quite readily available.

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    Maybe it's just me, but I would not use the 36VDC for relays. I suspect that is your stepper motor power supply.

    I'd just add a small 24VDC supply and use 24VDC relays.

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    I agree with those who suggest adding 24V for the relays. No need to risk disrupting something sensitive that runs off the other ones and 24V is pretty much industry standard. A supply to run a couple of relays can be as simple as a large wall wart type. I've got one I use for experimental lash-ups that puts out 2 amperes and has screw terminals.

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    I agree that you can't go wrong by using a separate 24 volt supply, assuming the Gecko outputs can accommodate that, which they probably can.

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    The 36v is for the stepper motors, certainly wouldn't want to disrupt them. My power supply has a 5v output also, which was capped off, I was wondering whether I could use that for the relays?

    I know that machine had a spindle power relay as an option, perhaps that was what the 5v was for.

    I have no problem using a 24v relay and power supply, but I really want to understand this stuff better, hence my original post


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