My setup is:
- Raspberry Pi Zero 2
- Waveshare USB/Ethernet Hub hat stacked on top (https://www.waveshare.com/eth-usb-hub-hat.htm), it communicates with the Raspberry via USB connector
- Waveshare Relay Board hat (https://www.waveshare.com/wiki/RPi_Relay_Board) is at the top, with 3 Relays.
On the Waveshare USB hub, I have plugged in two USB NFC Readers. I control the relay when I read a card.
Everything is working fine with the relay if I try to control 12 V light bulb. However, when I try to control a 12 V electric lock, even though the Waveshare relay board supposedly has an optocoupler, I guess what's happening is I experience EMF back from the inductive load of the electrical lock when I try do switch it.
![Image]()
(4)
(https://www.waveshare.com/rpi-relay-board.htm)
After switching it 2-3 times, sometimes even once, what's happening is it affects the USB readers, and they disconnect/reconnect, behave weirdly, or sometimes even turn off. That's not happening if I only try to switch ON/OFF the relay without anything connected to it, or as I said, If I try to control a 12 V light bulb. In that case, everything works well. The circuit for the bulb / lock is separate; I use the relay only as a switch.
I tried to power unstack the relay and power it separately, but the same thing was happening. I am pretty much convinced the problem is due to EMF, but I don't know what to do about it. I don't know if EMF is harmful enough for RPi0, but it certainly affects the USB devices. What could I possibly do to mitigate this?
- Raspberry Pi Zero 2
- Waveshare USB/Ethernet Hub hat stacked on top (https://www.waveshare.com/eth-usb-hub-hat.htm), it communicates with the Raspberry via USB connector
- Waveshare Relay Board hat (https://www.waveshare.com/wiki/RPi_Relay_Board) is at the top, with 3 Relays.
On the Waveshare USB hub, I have plugged in two USB NFC Readers. I control the relay when I read a card.
Everything is working fine with the relay if I try to control 12 V light bulb. However, when I try to control a 12 V electric lock, even though the Waveshare relay board supposedly has an optocoupler, I guess what's happening is I experience EMF back from the inductive load of the electrical lock when I try do switch it.
(4)(https://www.waveshare.com/rpi-relay-board.htm)
After switching it 2-3 times, sometimes even once, what's happening is it affects the USB readers, and they disconnect/reconnect, behave weirdly, or sometimes even turn off. That's not happening if I only try to switch ON/OFF the relay without anything connected to it, or as I said, If I try to control a 12 V light bulb. In that case, everything works well. The circuit for the bulb / lock is separate; I use the relay only as a switch.
I tried to power unstack the relay and power it separately, but the same thing was happening. I am pretty much convinced the problem is due to EMF, but I don't know what to do about it. I don't know if EMF is harmful enough for RPi0, but it certainly affects the USB devices. What could I possibly do to mitigate this?
Statistics: Posted by noumenon — Wed Oct 23, 2024 11:57 am — Replies 0 — Views 21