Reef-Pi The All In One Pi Challenge

[raketemensch]

Great thread, very useful information all over the place.

I'm hoping to build out a system myself this winter, and it looks like Michael Lane has made the Jebao part even easier -- a mars aqua board, a jebao 3s/4s board, AND a ph board. I hope to order all 3 shortly.

As a former homebrewer, the idea of having a good, cheap pH monitoring solution is kinda mindblowing.

 

[Mikeneedsahobby]

I saw on the main reef-pi thread that you had a doser pump fail on.

I’m using the jebao dp-4 doser as well. I have an adopter from @Michael Lane between the pwm board and dp-4. I have had a few times now that the uln2803 board failed. Twice this caused doser to fail off. The third time triggering 1 particular doser caused all dosers to run, but triggering the other 3 worked fine. The last case I caused by reversing voltage through the chip. The first two though have no reason that I know of to fail.

I’m wondering if you found the cause of your doser failure and if it has anything to do with the 2803 board???

 

[theatrus]

I saw on the main reef-pi thread that you had a doser pump fail on.

I’m using the jebao dp-4 doser as well. I have an adopter from @Michael Lane between the pwm board and dp-4. I have had a few times now that the uln2803 board failed. Twice this caused doser to fail off. The third time triggering 1 particular doser caused all dosers to run, but triggering the other 3 worked fine. The last case I caused by reversing voltage through the chip. The first two though have no reason that I know of to fail.

I’m wondering if you found the cause of your doser failure and if it has anything to do with the 2803 board???

The ULN2803 has on-board flyback diodes, so most motor loads should be safe. Is the COM pin tied to the same power supply that feeds the doser pumps?

 

[AquaRaider44]

I saw on the main reef-pi thread that you had a doser pump fail on.

I’m using the jebao dp-4 doser as well. I have an adopter from @Michael Lane between the pwm board and dp-4. I have had a few times now that the uln2803 board failed. Twice this caused doser to fail off. The third time triggering 1 particular doser caused all dosers to run, but triggering the other 3 worked fine. The last case I caused by reversing voltage through the chip. The first two though have no reason that I know of to fail.

I’m wondering if you found the cause of your doser failure and if it has anything to do with the 2803 board???

The ULN2803 has on-board flyback diodes, so most motor loads should be safe. Is the COM pin tied to the same power supply that feeds the doser pumps?

I tested it and it ended up being the reef pi. I have the latest boards that I helped to revise with @Michael Lane and no shorting or issues occurred. The last board i did have the ULN fail however but all failed off. I know this was a reef pi issue beacuse as soon as i restarted reef pi it fixed the issue and the doser was off and everything has worked fine ever since.

 

[Michael Lane]

The ULN2803 has on-board flyback diodes, so most motor loads should be safe. Is the COM pin tied to the same power supply that feeds the doser pumps?

The COM pin is connected to the same power supply running the pumps. It's a straight-forward design, pretty much straight from the data sheet.

There may be an issue running multiple pumps for extended periods of time, despite expected currents staying within the safe range in the data sheet. I have not been able to reproduce that issue, but I'm working on another version using discrete components in case the ULN2803 is overheating after a while.

 

[theatrus]

Since it has to be asked, what’s the source of the ULN chips?

It’s a pretty common part, and not technically sophisticated, so you know what that means...

 

[tsouth]

@AquaRaider44 Are you still around? We need your help over on the sponsored supporter thread for the Par Meter. Please send me a message.