OpenSprinkler › Forums › Hardware Questions › OpenSprinkler › Does Open Sprinkler AC have power supply minimum/maximum amperage? › Reply To: Does Open Sprinkler AC have power supply minimum/maximum amperage?
Why I’m asking–I’m not really going to have lots of irrigation zones running at the same time….
One of my OpenSprinkler Pi’s is located in the same area as my pool equipment. I’ll have four irrigation zones there, at most two zones on at a time (but probably just one, depending on the flow I can get at 50 psi at that location).
I’d also like to control the pool lights from the pi. They’re low wattage, LED lights, 5W max, 12VAC. The lights themselves (under water in the pool) are more than just LEDs–their color can be controlled by manually doing an on/off sequence to get the color you want. So, I’d be worried about trying to use DC instead of AC.
I was thinking I would use three channels of the OpenSprinkler board for powering (and color controlling) the three LED lights. I’d have to hack the board to power those channels from 12VAC instead of 24VAC needed for the irrigation valves.. Since I’d be hacking the pcb anyway, I could add wires not only for the 12VAC, but also the gnd connections for the pool light triacs.
I’d need a 24VAC to 12VAC transformer (haven’t found one yet, any suggestions would be welcome!).
The lights are 5W (max) each. At 12 volts, that’s 417 ma (each). So well within the maximum OpenSprinkler spec of 800 ma per channel. But, I think the sum is too much for the 16 mil triac gnd trace on the OpenSprinkler pcb.
Alternately, I could put 2:1 transformers on the OpenSprinkler channel outputs. That way I wouldn’t have to hack the OpenSprinkler pcb. Current would be 200 ma for the 5 watts at 24 volts, but sum still of the current looks too big for what looks like a 16 mil trace on the OpenSprinkler pcb.
I could also just add jumper wires for the triacs on the pcb and the “downstream” transformers. But, while that approach wouldn’t require me to cut traces on the pcb, I’d still have to do an “add wire” hack AND use multiple transformers.
So, I’d to hear that I’m missing something and the OpenSprinkler pcb can actually handle more total channel current than what a 16 mil trace would limit. But, I can certainly make it work, if I can find the transformers. Worst case, I guess I could wind my own.