Control string of lights with OpenSprinkler Pi

[navy2x]

Are there any modifications I would need to make in order to control a string of lights with the OSPI, such as this one? Could I just cut the plug off the end and hook the negative wire into the common on the OSPi, and the positive into one of the relay switches? I’m thinking I need at least a resistor, or some other modification so I don’t blow up my board.

I’ve read though this post already: http://rayshobby.net/?page_id=806. I’m just not sure if it applies to a string of lights. Thanks for any help anyone can provide.

[Ray]

This depends on the electric spec of the lights. Just quickly glancing over the link you provided, it seems this is using E12 light bulb, and I suppose it means it requires 110V powerline voltage, so you can’t directly light it up with OSPi, because OSPi outputs 24V AC which is far below 110V. There are several options

1. use OSPi to drive a relay and use relay to switch the lights. OSPi does have a built-in relay, but that’s only rated 3 Amp contact current, so likely you need an external relay.
2. use OSPi combined with an RF remote power socket to switch powerline devices. I have a blog post about it: http://rayshobby.net/?p=3381 (note that the blog post uses OpenSprinkler as example, but the same functionality can be implemented for OSPi).
3. instead of using 110V light bulb, use 12V LED lights. 12V LED lights can be directly connected to 24V AC output (because LED is intrinsically diode, it blocks half of the AC waves, making the effective voltage 12V).

[navy2x]

Ray, thank you for your assistance. In my online quest for a solution I came across this neat toy, the PowerSwitch Tail II.

The input takes anywhere from 3-12V to trigger the device, so if I use a voltage divider to lower the output voltage from the OSPi, I should be able to control this nicely from the OSPi. Do you see any problem in my logic?

[Ray]

Yes the power switch tail is a good solution.

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