5V device NOT 5V logic - Pi Automation Hat

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1

I have a Raspberry Pi 3 B+ and I have a device that uses 5V… Can I put a Pimoroni Automation Hat Mini (PIM487) “between” them and control the one with the relay on the other?

Everytime I Google I keep running across things that tell me about 5V logic controlled relays and that I shouldn’t use them with the 3.3V logic controlled Pi.

The specs I can find on the Automation Hat say “relay that can tolerate up to 2A at 24V” but I wanted to make sure before I dived in.

Thanks in advance!

2

The Raspberry Pi uses 3.3V logic. And has a limit on how much current a GPIO pin can supply. It would never be able to turn on a 5V relay if directly connected to a GPIO pin.
It will also likey damage that GPIO pin. Also, if you feed a 5V signal into a GPIO it will damage the Pi
Your plan to use the Automation Hat sounds to me like a good idea. You can either use the onboard relay, or one of the sinking outputs to ground / turn on the relay you have now.

3

To be clear, I don’t have any relays now. Just that when I searched for a relay that could control a 5V device all I found was “horrors” about using a relay designed for Arduino with the Pi.

Since this is a Pi Hat I assumed it would be safe for the Pi but I wanted to be sure that “up to 24V” meant I could still control something that used a MUCH lower voltage (which, again, is coincidentally the same voltage as an Arduino which generated a lot of “white noise” in my search results)

Thanks!

4

When it comes to relays, “up to 24V” means just that; you can run 0.5V through it if you like.

That said, it depends what sort of control you’re looking at; I suspect trying to do PWM through a relay will result in Bad Things :-)

5

I’m replacing the Time Clock from “yesteryear” that we still used to control the bells on the production floor. Apparently someone didn’t think it should stay on the wall and ripped it down.

So a Pi, the Automation Hat and a cron job that triggers a script that doesn’t really do anything but wait a few seconds between “relay on” and “relay off” should be all I need.

Thanks!