Just looked and the 2 ch board does not use the ULN2003... it uses discrete transistors/FETs to drive the relays, and a diode for the kickback clamp.
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The failure mode of the Songle relays is for the relay contacts to remain ON all the time. There have been other failure modes.
However this is not an intermittent failure. Since you can "recover" from a failure it is likely not the relay.
Where are you getting the 5V power to operate the Zigbee radio and relay driver?
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Are you asking me?
If so, there is a small SMPS on the board for powering the relays and the processor.
Also the USB input.
There is also a 3.3v linear regulator for the processor and the zigbee receiver.
You want to set the board into Self-Locking Mode which I believe is entered upon the third depression of the MODE button. Can't recall if this setting is lost with power loss but be mindful that it might be.
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Thanks, I ultimately figured that out and it does hold on a power outage.
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That setting is persistent on mine.
Great discussion so far. The single channel MHCOZY (ZG-001) has wreaked havoc on my Zigbee network. I find devices will be connected for many days without any issues. All the devices will be connecting directly to the Zigbee coordinator (a Sonoff Zigbee 3 USB dongle). For whatever reason, multiple sensors that have the MHCOZY relay in between them and the coordinator (so it should be repeating their signal) do not connect through the mains powered relay. Nothing does, they all just connect straight to the coordinator.
Today after coming back from a 3 day trip, I used Home Assistant to toggle the MHCOZY relay that is set to momentary/inching mode (btw is "inching" a real thing or a bad translation on the Amazon listing?) and it works fine. Press it again while the Garage Door opener is still going up and it stops it, but doesn't flip back to "off" status in the Home Assistant app. Press the switch again, nothing happens but it does change state to "off" in Home Assistant. The behavior persists through another test run. I didn't have time to keep trying and troubleshoot further to see if it was a fluke two in a row or if the relay was permanently acting up. However, I did notice that after that happened all four of my Zigbee door sensors were now not working. Most Zigbee devices that I would have previously expected to connect through that relay are now doing so according to a network visualization, but none of them are actually "working" in Home Assistant. Sensor events aren't making it to Home Assistant. It almost looks like the relay is repeating for all of the devices but not actually forwarding the traffic. (Please keep in mind that I am still learning about Zigbee and so my terminology may not be right and still looking to figure out how to troubleshoot this further). I reboot HA O/S (along with the Sonoff dongle) and this does not resolve anything. The devices stay this way for 5-6 hours at which point I unplug the MHCOZY relay from power. Then less than a few minutes later, everything reconnects to the Sonoff dongle and is working totally fine. Super frustrating and not the first time something like this has happened, this is just the first time I really put two and two together.
I am wondering if the "inductive kickback" theory applies here. If the MHCOZY device, after toggling it, caused it go into a somewhat functional but mostly zombie state where it's not capable of forwarding all of the Zigbee traffic it's supposed to for the downstream devices?
I was powering the MHCOZY with a USB adapter (Google MST3K-US) providing 5.1V and 850ma.
- Does anyone know what the minimum current needed by these relays is?
a. I assumed 850ma would be more than enough and curious if that's my issue. - How likely is it that the supplied voltage of 5.1V (instead of 5.0) could be causing issues?
- Would switching the relay to run off of 120V AC instead of using the USB port help anything?
I'm curious what others are using to power these devices and if that has anything to do with the issue.
What model is the Sonoff dongle - Sonoff ZBDongle-E or the Sonoff ZBDongle-P ?
Hi -- it's the ZBDongle-E.
It is very likely that changing it to ZBDongle-P will resolve the Zigbee connectivity problems in Home Assistant (ZHA?) mentioned above.
ZBDongle-E uses the same EFR32MG21 Zigbee SoC as in Hubitat C-8, hence the very similar problems with some new Zigbee 3.0 devices (mostly Tuya - for now…)
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