Qwiic Quad Relay fails to trigger (coil voltage?)

Qwiic System
1

Hello SparkFun support,

I am having an issue with two Qwiic Quad Relay (COM-15102) boards that I ordered. The problem is that one relay from each board does not trigger (we can refer to them as Relay #1 on board A and Relay #2 on Board B). The LEDs light up as expected. The other relays trigger as expected.

Build Details:
I have two of the board hooked up to an Raspberry Pi 3 B+ using the Qwiic pHat v2.0 (DEV-15945). There is also a Qwiic Keypad (COM-15290) on the i2c bus. I have the python code already written and everything is working as expected. No issues with communication.

I suspect the issue is related to power. The ATTiny84 on each board is receiving power from the Qwiic pHat, so that’s fine. I have a 12V 30A power supply hooked up in parallel to each barrel connector to power the relay circuit. I did not solder the 5V jumper on the underside of the board. Most of the relays operate as expected, it’s just these two where the LED lights but the relay does not flip. I used a meter across the relay contacts while their respective LEDs were lit, and measured 3.05V. I also measure 1.83V across the current limiting resistor in series with the coil, and 4.9V out of the onboard regulator, so everything checks out. If I use an external supply to put 3.3V accross the two misbehaving relay coils, they flip as expected. They’re just not getting enough voltage to go over the threshold using the onboard configuration.

I would have been fine with this and just bought another board, but it happened on two different relays on two different boards. I was planning to use these for several installations, and I don’t want to have to do rework on a dozen boards. I’ve gone through all the guides, checked the forum, and reviewed the Eagle files. It seems to just be a manufacturing defect. Any suggestions?

2

Greetings, XanthousKing. Thanks for the post and my apologies for the delay here.

We have ran into some similar issues while testing units at HQ and discovered that there is a design issue related to how much power is reaching the relay trigger circuit resulting in relays not working properly. A revision is in the works at the moment which will solve this issue, so keep an eye our for that.

Please fill out a return form here: https://www.sparkfun.com/returns

Once you have submitted a returns ticket it will enter our que and we will take care of this issue from there.

Please private message me if you have any more specific questions regarding your order. We apologize for the inconvenience and thank you for your patience on the matter.

Cheers.

3

Sorry for the delayed response, I was out-of-office due to the quarantine. I purchased the quad relay boards through Digikey because the SparkFun site was out of stock, and I’m well beyond the return window. I guess I’ll just eat these boards. Any estimate on when the next revision of the board will be released? I won’t be able to wait until 2021 to get this deployed.

4

In the final revision of my project I used another power supply, and it seems to have fixed the issue. The output voltage of the new 12V supply is nearly identical, and it’s well above the drop-out for the onboard regulator so I don’t know what’s up. Sounds like a me problem, though.

While there may or may not be something wrong with the board design itself, consider my particular issue resolved.

5

Awesome, glad to hear that the issue is resolved for now.

I hope you the best with your project.

Cheers for now.