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Im workin today so keep in mind ill respond as I can.
First off, those relay boards require 15-20ma Per channel to switch on and off, the pi can source or sink 16ma per gpio pin and only a total of 50ma for the whole pi, which is why you need to use an uln2803. 8 relays x 20ma each is 160ma with all relays on.
The uln2803 is an 8 channel transistor chip. The pi turns on the 2803, which can handle the current of the relay board much better.
This leads me to another thing. Those relay boards work by supplying VCC to the opticals and each relay input is actually sinking current to ground to turn the opticals on.
Id suggest using a uln2803 between the pi and relay board. Roll your own on a breadboard, or get one of the fantastic hats with one built in.
Yes even with the octocouplers...there are several reef pi specific hats that have the uln onboard...wont find them on amazon.15-20 ma per channel? even if they have optocoupler on-board? ... ok ill'try the uln2803 .. i don't find the hat on amazon.
Yes even with the octocouplers...there are several reef pi specific hats that have the uln onboard...wont find them on amazon.
@Michael Lane sells a nice goby hat on tindie
@robsworld78 sells nice hat type boards
@theatrus sells his pico board
Forgive me if i forgot anyone.
Anyways they make for a cleaner install and are big time savers.
15-20 ma per channel? even if they have optocoupler on-board? ... ok ill'try the uln2803 .. i don't find the hat on amazon.
I think this is something different. I did a quick search and see lots of connection issues for various reasons, one common was wifi issues. If you use wifi I would try a hard wire connection and if you have an extra SD card maybe load the Raspberry Pi OS as it won't be a problem now.
I use a pi zero w, never had a wifi issue, but i have a good wifi router. I did make sure the pi was not in a metal enclosure which would block signal.I did some digging through the syslogs and found a basic pattern - I'd stop seeing API requests, then about 5-10 minutes later it would log a carrier lost, and then unregister everything and reconnect - so I think the problem was that it was dropping off the wifi and not realizing it. I'm not sure if my crappy wifi router is dropping the connection, or if the pi is.
Anyways - I put a script in that basically scans for wifi networks every 2 minutes and then pings the router - and its been up for 12 hours now.
Got pH and temp logging and alerts set up. Knocked the temp probe out this morning and started getting text messages. They're false alarms, but cool to see.
Gonna give it a couple days and make sure it stays up - and if it does I'll start moving my less vital stuff onto it first.
The octocouplers on those boards let either a 3.3 or a 5 v signal turn on the octocoupler to let the relays work. Yes they could spec 5ma ones but i tested my boards which are the same board as the posters and they run 15-20ma.Optocouplers are.. an LED and a photo sensor potted together in a small box, so its quite normal. Usually the optocouplers can run down to about 5mA, it all depends on the part they specced.
To be honest I'm not sure why they add optocouplers to a relay board, unless they're scared of the quality of relay they provide. If you just power both sides of the optocoupler with the same supply there is no isolation or other gain.
It's basically sitting on my desk - router is about 6 feet away. I don't think it's a signal issue.I use a pi zero w, never had a wifi issue, but i have a good wifi router. I did make sure the pi was not in a metal enclosure which would block signal.
Is your stand , enclosure or the combo causimg wifi signal to the pi to be weak perhaps?

It should be possible using an ATO. A momentary switch is set up as an Input should be able to trigger a Macro. When I last played with that, I could not get an input on an ATO to trigger a Macro in any way. But it should be possible as the options are built in.
Those problems all went away since I switched to google WiFi.
Your hysteresis is 0 in the picture, I do not think that will work, maybe better change it to 0.1 like Ranjib mentioned!@Ranjib my ph probe into the calcium reactor didn't work well.
I can't set the hysteresis, every minute the solenoid valve open for one minute and turn off... I think there is something wrong... Maybe a DB wiping could be the solution?
the PH is pretty linear
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It's basically sitting on my desk - router is about 6 feet away. I don't think it's a signal issue.
I think the router was killing the connection because it isn't seeing activity. The router's ui Is awful so I'm not really sure past that.
It's basically sitting on my desk - router is about 6 feet away. I don't think it's a signal issue.
I think the router was killing the connection because it isn't seeing activity. The router's ui Is awful so I'm not really sure past that.
The octocouplers on those boards let either a 3.3 or a 5 v signal turn on the octocoupler to let the relays work. Yes they could spec 5ma ones but i tested my boards which are the same board as the posters and they run 15-20ma.
The board has a jumper that determines if you run completely isolated or commonly grounded. People wiring things wrong were hosing their arduinos so i think that is the reasoning for isolation.
These boards are kind of a universal fit for arduinos and pi and general experimenting. The relays are the songle ones like in the american DJ power strip so not very robust.
That being said, even though i got a great ebay deal on a crapload of nice phoenix contact 24v mini relays with inductive protection and suppression with din rail sockets to go with them, that I was going to change out if my cheapy board failed. The cheapy relays have been working for 2 years running my heaters and return pump. Maybe its because I run most of the relays normally closed in case reef pi goes nuts. Reef pi has to energize the relays to turn them off so most of the time the relay coils are sitting not energized.
We had some sort of power-surge event last year that damaged or killed everything that was connected to our Comcast lines, and nothing else - cable modem, both routers, a pc motherboard, hdmi ports on multiple tvs, ethernet ports on a couple other things - just a mess. It melted the aluminum casing for the RG6 distributor/amp comcast had put in.There are a lot of bad implentations of specs out there for Wifi, especially on home routers. Also, the space is really complex now with multiple power management modes, roaming hand-offs, etc so I'm not too surprised there is some funkiness with idle devices.
If you're 6 feet away, I'd recommend a cable - much more reliable in nearly every case :)
I would recommend using a current limit resistor. I use 220 ohms, but the value isn't critical. The other end of float should be connected to 3.3v since the internal pull down is enabled by default (assuming GPIO 9 or higher).
We had some sort of power-surge event last year that damaged or killed everything that was connected to our Comcast lines, and nothing else - cable modem, both routers, a pc motherboard, hdmi ports on multiple tvs, ethernet ports on a couple other things - just a mess. It melted the aluminum casing for the RG6 distributor/amp comcast had put in.
In the interest of expediency, while trying to get Comcast to replace all the stuff that they fried (I'm still fighting with them) - I bought a cheap router, threw it in my office, and used one line from the cable modem (in the garage with the network distribution ) to my office for the uplink, and the other one back down to feed into the distro panel. So between that, my PC, my work laptop (yay, covid), and a networked printer, I'm out of ports near the tank and on the router.
I really just need to buy a mesh setup at some point, and put a gigabit router back in the garage and clean up all the rube-goldberg nonsense.
On a positive note - we're going on about 36 hours now with no connectivity issues. And the pH fluctuation have gone from 7.9->8.1 up to 8.1->8.25 since I added a DIY chaeto reactor and am running it at night. Gonna start moving timers/etc onto the reef-pi next.