Octoprint Relay board

I tested this relay board out on a breadboard. seems to work well. I had to move some components around to scale it down to the size board i had laying around. This is for a remote switch for the 3d printer i got. I'm going to connect it to the gpio pints of the raspberry pi/ octoprint server to shut it down remotely.

I'll test it out on a something else like a light before the printer to ensure i don't fry it. Fingers x'd.

Top Comments

rctho over 7 years ago +3

I finally got this thing up and running and it works great turning the printer on and off. After the breadboard prototype, i had to move stuff around and went a lil' off track from the original design…
carmelito over 7 years ago +2

This is a great idea.Hoping you will post an update, as soon as you have it working with your 3D printer..Thanks
jw0752 over 7 years ago +2

Hi Craig, This is a good example of planning and testing prior to building. With this approach you have a much better chance of success. John

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mcb1 over 7 years ago

What voltage is the relay contacts going to switch.?

If you are switching mains voltages then using optocouplers might be the safer method of ensuring isolation.

Mark
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rctho over 7 years ago in reply to mcb1

The voltage is 12 with 7 amps. You think that will require optocouplers? Not gonna lie, I don't know what that is. I'm going to search online then see if there are any kicking around in the lab in case i need them.
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rctho over 7 years ago in reply to mcb1

The voltage is 12 with 7 amps. You think that will require optocouplers? Not gonna lie, I don't know what that is. I'm going to search online then see if there are any kicking around in the lab in case i need them.
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Robert Peter Oakes over 7 years ago in reply to rctho

You should not need an opto isolator but you should be aware of keeping the POWER current away from the microcontroller current

So power the relay / LEDs from a separate supply to the PI and just share a common ground

Regards

Peter
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rctho over 7 years ago in reply to Robert Peter Oakes

Thanks Peter. I'll give that a shot. I wanted to try to power both the pi and relay with the same line but somehow divide it with a 5v transformer/regulator and the relay with a common ground, but you're saying that's not a good idea?
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Robert Peter Oakes over 7 years ago in reply to rctho

Correct, you can get it to work but it is much easier to keep the power side separate from the PI, the PI wants 5V, nice and clean, the relays and the LED loads want probably 12V and it will have quite a bit of noise when switching so if you want to avoid hard to diagnose issues, keep them separate except for a common ground
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mcb1 over 7 years ago in reply to rctho

The voltage is 12 with 7 amps
In that case you should be fine.
You'll need to add some wire onto the pcb traces.

If it's using a supply from a computer, they often fool it by bridging out the enable wire.
You might be able to interupt that instead.

Mark
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rctho over 7 years ago in reply to mcb1

Thats a good idea. I am concerned about how much juice is flowing through such a lil' circuit. I'll add today. Thanks for the tip.
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