Silent X10 Mod (cheap SSR)

I’m feeling a bit retro for the holidays, so here’s another classic: If you’ve got a non-dimming X10 switch, you’ve experienced the incredibly loud, obnoxious sound that it makes when you switch it on or off. (Mine’s in my stairwell) There’s a simple mod to silence the thing: remove the triac relay and replace it with a solid state relay. SSRs are a bit expensive, running at least $10 each last time I checked. [Willis Dair] realized that he could build his own, inexpensive SSR with an optoisolator and an alternistor(AKA Triac). The resulting circuit runs about $3 in parts.

21 thoughts on “Silent X10 Mod (cheap SSR)

  1. It’s important to remember that the mechanical relays in these switches are designed to handle high load items, which an electronic relay often can’t handle. It’s what allows the $50 switch to power motors, and heavy loads like 600V of incandescent lights, or a water heater. Replacing it could jeopardize the relative safety of the mechanical relay. The noise of the relay moving might be annoying but it’s providing a safety feature

  2. what kind of light would a normal household have thats 600w? I have a shop halogen light thats 500w. I couldn’t imagine a single light in a house with a normal plug requiring 600w.

    As far as safety is concerned a solid state relay is a lot more safe in my opinion, given its rated to handle it load obviously. The spark a mechanical relay causes could lead to more problems than a SSR. Further more after extended use of a mech relay the contacts start to deteriorate(like welding). A SSR is only unsafe if not used properly, just like everything else in the world.

  3. “13. what kind of light would a normal household have thats 600w? i have a shop halogen light thats 500w. i couldn’t imagine a single light in a house with a normal plug requiring 600w.”

    e.g. Multiple recessed lighting like kitchens and living rooms have a cumulative load. Exterior house lighting like spot lights, two on each unit 2 to 4 units adds up.

    It’s the same for dimmers. If you want to dim 6 recessed fixtures that have 100W bulbs you would need a 600W dimmer.

  4. I agree with boyd – those stylish indoor recessed lights or mini-spotlights for paintings etc. can be 50w each, and with 20 of them around a room you could easily end up with 1kW of lighting.

  5. I’d hope that if you’re messing with home electronics, and hacking them, no less, that you’d know how to calculate total load and choose the appropriate SSD. You could also put a pair of SSD switches in to get the load needed if one wasn’t enough.

  6. @14,15

    the X10 modules are for outlets. I dont play with x10 at all so maybe they make some for hardwiring, but I dont know. My questions is what kind of light with a standard plug on it would require 600w, as the article shows how to modify a x10 module for a standard electrical outlet.

  7. He’s using a 15 amp TRIAC, with fairly large heat sink. If something fails, it’s not going to be because he plugged in 700W of anything. He’s even using what Teccor calls a “snubberless” triac, which means it deals pretty well with reactive loads. He’s also using a zero-crossing-detecting optoisolator, i.e. what he’s built is _identical_ to a commercial SSR — just not potted in lots of epoxy.

    Furthermore, unlike conventional relays, SSRs won’t fail after N switchings (due to mechanical wear and that it arcs inside the relay every single time you switch with a load). It’s pretty clear to me that the X10 guys used conventional relays because they cost 1/10th as much (and 1/3rd as much as the home-built SSR here), nothing more.

  8. The (outdated) article discuss the multiple types of switches X10 makes including the wall switch, which use the same electronics. I have 480 W of lighting on a single switch in my living room. It’s normal in a lot of houses to have a high load on a single switch. It’s not just a plug-in module they have all sorts of hard wired units.

    The updated version of the website that started the blog states that there is a 300W maximum load on this mod. They are using 5 amp SSR’s in many of their mods except the hot water heater mod, where he used a 50 amp.

    I’ll keep my UL rated relays that control my 480W of incandescent recessed lighting and my 600W transformer (9 amp draw). At least we didn’t start talking about dimmer loads too.

    Here’s the updated site for X-10 mods.

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