Electronic question converting AC out to DC - Troubleshooting - Rachio Community
Electronic question converting AC out to DC
post by scrambler on Aug 14, 2025
Hi, I have an electronic question.
One of my Rachio zones is on a wireless transmitter. I have a Wireless controller that is triggered by the Rachio zone output, and sends a signal to a receiver board that drives the sprinkler valve.
The wireless controller can take either AC or DC input, so for now the Rachio zone output was connected directly to the Controller input.
But it turns out the controller would prefer DC, as the AC input is unreliable and tends to die after a while.
So I want to use a DC input on the controller instead of the 24VAC signal of the Rachio zone output.
I figured there would be two ways to do that.
Use a 24VAC to 24VDC converter like this
That would take the Rachio valve signal and convert it to DC for the wireless controller.
I tried it, but for some reason, the presence of the Converter makes the Rachio detect a valve error (output red) and cuts off the signal.
Anyone knows why adding the AC/DC converter would cause an error on the Rachio output?
- Use a 24VAC relay, that will take the Rachio Output signal to close a circuit feeding 24DC to the controller input.
Or: OONO DPST
Before I try that I would like to know why solution one did not work to get a sense on whether the second one could work.
Thank you to anyone who could shed some light on this.
post by Thomas_Lerman on Aug 14, 2025
The specification says “The AC to DC Converter Input voltage:24V(AC) Output voltage:24V(DC);Current:4A”. I presume the 4A is on the output side and if so, it does not say what is on the input. It seems most valves are 200-300mA when energized. I do not know what kind of current the transmitter draws nor what the loss is from the converter. This information may identify the issue.
post by scrambler on Aug 14, 2025
Thanks,
Given it works when the rachio output goes directly in the controller, I assumed the controller was drawing a compatible amount of current.
So I assumed that would also be true at the input of the converter.
One possible issue is that the losses are so big in the converter that the converter draws too much power and that causes the rachio to shut off the output.
If that is the issue then the relay will work as it will draw very little.
So my question is whether anyone can think of another reason the converter creates the error.
post by Thomas_Lerman on Aug 15, 2025
Do you have a link to specs for the wireless controller?
post by scrambler on Aug 15, 2025
Not much there, and the issue is not with the controller that works when connected directly, but with the introduction of the converter.
I will see if I can find out the overhead power consumption of the converter.
I ordered the $15 24VAC relay that uses only 17mA and will try that too.
post by ady624 on Aug 15, 2025
I would not worry about it and leave it at AC. but if you really insist, maybe use a simple rectifier bridge and capacitor filter to smooth out the output. The problem is that the initial charge of any capacitor in the system would draw more energy (and current, for that matter) to exceed the rachio max output.
A very basic rectifier here Amazon.com
you may still have the same issue during rush current stage. Also note that DC voltage is a little below the ac voltage times square root of 2, meaning a 24V AC will produce around 32-34V DC.
post by scrambler on Aug 15, 2025
Thanks,
I dont have a choice, the Inputs using AC are dying after a while and the manufacturer is aware of the issue and suggested DC should not have the issue.
Testing DC on an input that no longer works with AC appears to work.
I am going to test the relay, that has very little Amp draw and should not trip the Rachio.
The AC to DC converter I bought converts the 27VAC of the Rachio to 24DC exactly.
post by ady624 on Aug 15, 2025
got it. Yes, the relay path is the safest bet as it physically separates the two circuits, shielding each device from the other. Also, no inrush current (well, not large enough).
post by Piney on Aug 15, 2025
I use a couple of 24vac coil relays, triggered by a zone activation. They both work fine
I use these to operate a mosquito misting system.
post by scrambler on Aug 15, 2025
Thanks, good to know
post by Thomas_Lerman on Aug 15, 2025
I also have a relay to run my water feature
post by scrambler on Aug 18, 2025
So the small 24VAC relay works great, when the Rachio activates the 24VAC zone signal, it feeds a 12VDC coming from the controller power supply on the controller input.
Now that relay has a small led, and I noticed the led lights up even when the zone is not activated, So I measured the voltage between the outputs common and the zone output when not active, and there is a residual 3.8Volts there…
Is that normal, and if so what is the purpose of it?
Is that a flaw in Rachio 3 (does everyone has that residual voltage on inactive zone outputs)?
Is that a defect of just my unit?
Appreciate if anyone knows or can measure the tension on some of their inactive zones.
Thanks
post by ady624 on Aug 18, 2025
Rachio uses solid state switching (triacs most likely) which can have residual currents flowing. The LED is most likely in series with a resistor and if the two have high enough resistance they can see enough residual voltage to open the diode gate forward and emit light, but faintly. Is the LED full on or faint?!
post by scrambler on Aug 18, 2025
It is not full on. Halfway I would say.
I just hope it does not mess up the relay.
Do you see that same voltage on yours?
post by ady624 on Aug 18, 2025
I can test when I get home. Do you see the same on other ports? As long as the relay is not humming or buzzing you are ok, there is too little current to energize the coil. Do you see those 3V while open or with the relay connected? What do you see open, what do you see with relay connected (all while zone is off) and what do you see on other off zones?
post by ady624 on Aug 18, 2025
Well, good you asked, because other outputs do not have the issue.
It turns out the leak comes from a second relay also connected to the zone output in question
That relay powers the wireless transmitter only when the zone is active, and keeps it alive a few seconds after it shuts down with a delay on break, to make sure the transmitter can send the close valve command.
So the leak comes from that relay and not the Rachio…
Maybe I need to look for a better one…
post by ady624 on Aug 18, 2025
well that’s not peachy. The silent side is probably putting up more effort to throw the relay, I would say it is safe to assume this is no bueno. Can you possibly drive both devices through two relays driven by rachio? Got any specs on the relay? what is the coil current draw? any part number? As long as it is below 200mA you should be fine driving two relays. Got a master valve? Complicates things as it uses up yet more current…
post by scrambler on Aug 18, 2025
This is the delay on break relay I am using to power the transmitter only when the zone is active
And this is what the wiring looks like
post by ady624 on Aug 19, 2025
Connect pin 4 of the ICM253 to Rachio (-) via an SPST relay driven by zone 3 and Common? this way you insulate Zone3 from the leaky delayed relay. That’s what I would do.
post by scrambler on Aug 19, 2025
Good idea, one more relay… This things is started to look like a refinery!
post by ady624 on Aug 19, 2025
how I designed it…
post by scrambler on Aug 19, 2025
post by scrambler on Aug 21, 2025
Final diagram for anyone interested
post by ady624 on Aug 22, 2025
may I ask, why not leave the transmitter always on and just drive it with a relay from that zone? Any reason you want the transmitter to be powered off (I understand the need for delay) between runs?
post by scrambler on Aug 22, 2025
Two reasons.
I want to minimize the battery usage of the receiver, and I think when the transmitter is on, it keeps a handshake with the receiver possibly making it use more battery.
I thought it would extend its life, the watering is 30mn usually once a week or less in the winter, compare to 24/7.
Both of these may not be a significant as I think, just decided to maximize them.