Imp enabled A/C switch

Something you might be interested in if you haven’t come across yet …

I picked up a couple of these last year to use at a second home. They work, but the WiFi can be a bit funky … I believe an Imp-based design would certainly have a big edge over this implementation. (I’ve since moved on to trying out some Belkin WeMo devices, as well as using Z_wave outlets).

My interest in them at this point has become more of a reverse engineering effort … it a pretty reasonable packaging job, and I’ve been starting to look at what they’re using for the +5/+3.3v AC/DC converter to power the processor and WiFi chip. I’d like to come up with a lower cost alternative to the Recom/CUI parts.

Anyway, just an fyi …

@jwehr, Zero Cross … that’s something I had forgotten about. Good catch. Zero Cross are used a lot where I work, for electric kilns and heaters (inductive).

Yeah, its a little frustrating. I really like using SSRs despite the cost, since they don’t click. I want my switches to work with whatever is plugged into them, so unless I can figure out a good solution, I’ll be back to mechanical relays. I’m going to email Crydom and see if they have any solutions. I didn’t notice anything odd with the non-zero cross ssrs that I was using first, but perhaps I didn’t switch enough different loads.

Thanks for you help.

When I’ve used SSR’s in the past for strings of lights, I know the LED ones don’t turn off, even with a full string of LED lights. What I did was added another small decoration to the same outlet … a snowman with an incandescent bulb in it. That’s all it took to clamp the SSR shut (off). I’m guessing it was a 7Watt bulb? Let us know what Crydom says … it would be interesting to learn.

Edit thought I figured this out… didn’t.

Here’s my stupid idea of the day.

Why not do a version with a DMX output, the idea being as well as turning your holiday lights on and off you could change their colours etc

There was a thread before about creating good DMX

Definitely a good idea… As far as my jack-o-latern goes, if we get the next firmware update before halloween, I’ll stop using the switch and just power the NeoPixels with an Imp… change patterns and colors…

Very neat. I just built a similar thing for controlling a hot water cylinder element. I tried a solid state relay to drive an existing contactor but I hit two issues.

  1. Solid State relays have off leakage which was enough to keep the contactor on.
  2. Solid State relays need a minimum load, mine was 50mA but my contactor coil only drew 10mA which meant I had to use wire wound resistors to increase the load, these got way too hot.

I ditched the solid state relay in favor of a small mechanical 5 Volt Coil relay that is good for 240V 10 Amps, more enough to power the contactor. I also could use the normal on contact so if my Imp device fails the my HW cylinder does not switch off. The imp can’t power the relay directly but this was easily solved by using a low power FET. Found that this approach was heaps cheaper than a SSR too.

Welcome to the world of SSR’s. They are what they are.

I personally would not use an imp or any other smart controller to control any critical devices in my home. At least not without a dumb backup system that would protect for overheating or freezing if the controller lost communication or died. The idea of controlling a furnace, for example, is not on my list. Even using “The Nest” doesn’t seem like a good idea to me.

Not that any of that pertains to this discussion … I just want to make sure people consider what they are controlling and how to build-in some protection from failures.

Nest has a “backup controller” in the back of the unit; this is a separate MCU that will, even if the main CPU goes AWOL, ensure that the temperature range is maintained.