Controlling valves and 12VAC LED lighting

[davethomaspilot]

I started this in another thread where I asked about total current carrying capacity of the OSPi (I think there’s a 16 mil trace that must carry the sum of all the channel currents).

I started this post because I’d be doing something a bit wierd, and would appreciate more “sets of eyes” to see if there’s a better or easier way….

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 four channels of the OpenSprinkler board for powering (and color controlling) the four LED lights. I’d have to hack the pcb board to power those channels from a separate 12VAC input instead of 24VAC needed for the OSPi (so it can provide 24VAC to the valves).

I’m thinking I coul remove TVS 5-8 and wire 12VAC to there. 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. This would eliminate any issue with the 16 mil traces.

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.

Currently, there’s a huge 12VAC transformer with a cable to the same post that I’ll locate the OSPi+ box. I’d use that supply for powering four of the OSPi triacs. I’d use the secondary of a 12VAC output, center tapped transformer to get the 24VAC to power the OSPI so the valves can get 24VAC.

Something like this from Digikey, with the secondary windings series connected:

http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=194802880&uq=635965052582209734

Seems like I should be able to apply 12VAC to one of the windings, and get 24VAC at 1A across the two windings connected in series. I’d insulate the “primary” side, since 110VAC or higher will be on that side.

It’s a hack, but the end result seems much cleaner than dedicating another Ospi, and power supply for the 12VAC switching.

Comments welcome!

[Ray]

Before I start responding here, maybe I will wait for you to respond to my reply to the other thread:
https://opensprinkler.com/forums/topic/does-open-sprinkler-ac-have-power-supply-minimummaximum-amperage/#post-42097
as I don’t want to ask the same questions repeatedly.

[insight3fl]

Not sure this will help you, but I am powering my 12v pool light using a 24v relay connected to zone 6 of my controller. While it is just one color, I would imagine you could program the zone to go on and off in quick sequences to get the color you want? I mounted the relay in the transformer box for the light and ran the two wires back to my sprinkler value manifold where I had zone 6 wire unused. I am breaking the existing switch to the light with the 110v relay contacts to control on and off leaving the switch in the on position all the time now.

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