I’m not an electronics engineer; I think I’d call myself an intermediate hobbyist, amd I’m not really knowledgeable about the details of dimmer switches. In particular, I get the general concept of how the switch works in non-neutral mode, but definitely don’t know the specifics of what limitations that introduces. But in my mostly-uneducated opinion, what he’s saying sounds reasonable to me.
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I’m surprised they are using the dimming mosfets for zero cross detection. I’ve mostly seen dedicated/isolated circuitry for that. Perhaps theress no room/cost of components, but then you’re free to use trailing edge dimming.
So the relay is energized the entire time the switch/load is turned off? Seems backwards, but i guess relays can fail in either position.
It only has to operate for dumb switches. You don’t really enable it for dumb switches, when you select 3-way with a dumb switch mode it starts operating because it has to.
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Well, the switch doesn’t click when you turn power on, right? It makes sense for the relay to only be on in dumb 3-way mode when the traveler is in use. That would keep it off in 1-pole mode and aux switch mode so off in most modes. The click was added just so you could hear a click when you turned it on or off. Well, it might keep the MOSFETs turned-on so the relay click immediately connects the MOSFETs to the load. That part can’t be determined from looking at output waveforms.
Not sure, I’ve not installed mine yet! 
They were slated for ballast loads and plans changed once I started reading that it wasn’t what I remembered.
The relay swaps the MOSFETs output from being connected to the load terminal to the traveler terminal. For the dumb three way the AC has to swap terminals to work but for a single way installation that is optional as the MOSFETs are used to interrupt the AC so it is not required to switch it from the Load to Traveler terminal. Ideally the design would have had a second relay that bypasses the MOSFETs for ON/OFF operation but it seems there was not enough room.
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It is energized because that is the state for the incoming AC to be passed from the Line to Traveler and not Line to Load.
Ya, kind of exactly like the explanation I posted first in this thread describing what the relay does. You’re not telling me anything I don’t already know.
Honestly the more I see how these devices work the more I really wish it was multiple SKUs
People who are buying HA gear typically don’t want or care that the other switch in a 3 way needs to be smart.
Get rid of the relay (or make the relay actually bypass the MOSFET’s), use the traveler for communication, this can still work in dumb mode but it means the smart switch has to be at the load wiring. There is no reason you need to be switching line power to/from the traveler.
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For an on-off switch, to me it should
- require a neutral
- have a physical or solid-state relay with pure sine wave output
For dimmers, I always buy the neutral version (if available) as my locations all have it. Dimming seems to just work better with one.
I hope the next series of Blue products have the same SKU as the Red series did.
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For an on-off switch I’d actually prefer the simplicity and increased current carrying capacity of a relay.
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Just chiming in to add that I’ve been really disappointed with the dimming tech. I’ve installed 20 dimmers and nearly every one has flickering issues when dimmed - across at least ~7 different fixture types all with explicitly-dimmable LED bulbs. Really hoping something can be done at the firmware level vs requiring a new SKU+buying new switches.
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+1 I’m also not thrilled with the dimming.
Most of my ceiling lights are (from Costco) Feit Flood Lights. I changed from both dumb dimmers and some TP Link dimmers (HS220) . Neither of these had issues and dimmed smoothly.
These dimmers both have flickering when not at 100% brightness… and the ramp up / ramp down is very quantized / visually steppy. I’ve avoided the ramp up / down frustration by setting the ramp rate to zero, but I know the HS220 worked smoothly at least.
I also hope there is a FW possibility for an update. I’ve got neutral wires in my house and would prefer to use them if it makes the dimmer better.
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Reading this thread, it sounds like (at least some) MOSFET dimmer implementations can work either on the leading or trailing edge, depending on when the gate signal is switched. I assume (and hope) that this gate comes from the SOIC that makes the switch smart. If so, there’s some hope that a firmware update could make these switches run with trailing-edge.
@Eric_Inovelli @EricM_Inovelli there do seem to be at least some folks interested in this- does your manufacturer think it’s possible? If so, perhaps a forum poll to gauge real interest before you pay them to write new firmware. There’s the small detail of bifurcating firmware branches, since some people won’t want to lose non-neutral 3-way detection, but that’s a problem for down the road. For now: is it possible with existing hardware? If yes, is there enough demand to make it happen? You know how I’d vote…
Edit- better yet, firmware that can handle both gate timings would keep everyone on the same branch, assuming appropriate checks are implemented to disable functions that won’t work when using reverse-phase mode.
Not to shoot down your bulbs, but Feit bulbs have been known to cause issues with other switch manufacturers too. I had Feit bulbs (from Costco) with my a red series dimmer and it was very choppy (never did have flashing issues though). I changed out the bulbs where I could in my last home.
Zooz even puts a statement on their website.
I’ve always wondered what are different about Feit that Zooz explicitly calls them out. We’ve used a couple of Feit LEDs on red and black dimmers and didn’t notice anything odd.
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I don’t dispute that Feit bulbs are cheaply made and of generally poor quality- too many reports of issues. However, the one Blue I have installed replaced a Zooz Zen 27- that circuit consists of six Feit bulbs in ceiling cans. The Zen 27, which uses trailing edge dimming, worked perfectly wrt dimming- no buzzing, flickering, or flashing. The Blue 2-1 that replaced it causes a noticeable buzz when dimming below 90%, and is incapable of driving those bulbs to very low dimming levels. I have other bones to pick over the Zen 27, but in terms of dimming it’s by far thr better choice for my single room with Feit bulbs.
Wow. I didn’t realize these were so widely disliked. Okay so noted about them not being high quality bulbs. I’ll look for others as I gradually replace them. Its just unfortunate because my previous switches didn’t show off their flaws.
Thanks for the information!
You can look here for some potential candidates. I wouldn’t replace all at once. Maybe try a couple from HD and see which work. If they don’t work, return for refund.