Capacitor in box for touch switch

Found this Tuya Zigbee touch switch on AliExpress

There is a capacitor in the box that the schematic shows should be wired in series with the neutral side of the circuit. Yet the instructions state :’ Without neutral wire is installed. The yellow Capacitor components must be distributed in parallel to L and N of the lamp holder connected in L1 position (As shown in the wiring diagram)’

The diagram shows a series connection yet the instructions state parallel.

What is the purpose of this capacitor? I have connected the switch with the capacitor and without and did not notice any difference. Used the ‘Generic Zigbee Switch’ driver.

Possibly it is something like this?

So it appears that it is to keep the light from flickering. I don’t notice that, so am I safe to leave it out?

If that's what it is for, probably. But I don't know enough about those sorts of things to give you a good answer.

All dimming levels? They don’t usually flicker on high.

This is just an on off switch. The capacitor is used when the load is 4 watts or less to remove the flickering. This is supposed to be in parallel right at the load.


I see. Maybe it’s an issue at 50Hz, which is what their generators output.

When a smart dimmer is installed in a location where no neutral is available, the dimmer/radio "steals" power from the load. When the load is OFF, the dimmer allows a small current to flow through the load. This current needs to be large enough to power the dimmer/radio but small enough to not light the controlled device.

To help this out, a capacitor will allow current to flow, some through the load and some through the capacitor. For reasons we won't discuss here, the capacitor does not consume any real power so it is the ideal component for such use.

I've NEVER seen a similar capacitor in series with any lighting system. I suspect it's a typo.

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Thank you for the clarification. Again, this is not a dimmer. It is a on/off switch.

Been working great and no flickering.

Interesting, I've not seen a "no neutral" switch only before. I guess the "touch" circuitry requires the same "leakage" current as a dimmer. Note if you have to change the bulb, with this unit connected there is some power on the bulb. Usually not an issue but good to know.

I actually bought one on Amazon, but I haven't tried it yet. I thought one of my Third reality switches, the type that goes over the top of a switch, had died and I saw this and decided to give it a try. Turned out it was the early Zigbee issues with my C8. They are still in the box.

The picture is correct. It shows the cap is in parallel to the load. The load is the circle with the x inside. The L1,L2.... etc are the connection terminals to the switch.

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