user0068334
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Joined: Mon May 20, 2019 12:24 am

Down convert +24DC to 5V

Mon May 20, 2019 12:30 am

Hi all!

I was going to turn one of the Pis I have into a wireless remote for my garage door following some tutorials online (first ever use with GPIO).

It all seems fairly basic on the backend stuff but I wanted to know what the repercussions would be in my situation:

I have 4 terminals on my garage door motor:
1. Wall switch 1
2. Wall switch 2
3. COM
4. +24VDC

I was going to get a DC converter to go from 24V to 5V for the Pi, but then started getting confused because the terminal is only +ve 24V and there's no -ve terminal.

What would happen if I plugged it into the DC converter without the negative half? Would I fry the Pi, or would it not be complete and just not work?

dl324
Posts: 107
Joined: Mon May 06, 2019 7:33 pm
Location: Pacific Northwest, USA

Re: Down convert +24DC to 5V

Mon May 20, 2019 12:36 am

You'd fry your Pi.

-ve could refer to a negative supply but, in your case, it probably means ground. Measure the voltage from +ve to GND, I suspect you'll get 24V.

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Gavinmc42
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Joined: Wed Aug 28, 2013 3:31 am

Re: Down convert +24DC to 5V

Mon May 20, 2019 1:56 am

COM is short for COMmon ground.
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scotty101
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Re: Down convert +24DC to 5V

Mon May 20, 2019 6:50 am

dl324 wrote:
Mon May 20, 2019 12:36 am
You'd fry your Pi.
Wrong answer. Nothing would happen because there wouldn't be a complete circuit.

In this case the COM pin should be used as ground
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davidcoton
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Location: Cambridge, UK

Re: Down convert +24DC to 5V

Mon May 20, 2019 8:20 am

scotty101 wrote:
Mon May 20, 2019 6:50 am
dl324 wrote:
Mon May 20, 2019 12:36 am
You'd fry your Pi.
Wrong answer. Nothing would happen because there wouldn't be a complete circuit.
Depends what else is connected and how. I wouldn't rely on "Nothing", but "fry" is not certain.
scotty101 wrote:
Mon May 20, 2019 6:50 am
In this case the COM pin should be used as ground
+1
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ankith26
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Re: Down convert +24DC to 5V

Mon May 20, 2019 10:11 am

I would suggest getting something like thishttps://www.amazon.co.uk/Adapter-Conver ... way&sr=8-4
Connect +24 VDC to red wire and COM to black wire.
And please don't post asking whether 3amps will fry the pi..
If you know about electronics, you will know that any device always consumes current that is sufficient to overcome load, and in case of pi it will range from 1 to 2.5 amps. Make sure not to connect anything more than pi, since 3amp is the max this device can give.
And just to tell , your pi will be fine if you do things right
My website is at https://pratt.ml
Hope it runs (which it wont)

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