Sonoff Wi Fi DIY MINI smart switch issue.

[PeakSteve]

Has anyone had an intermittency issue with a Sonoff DIY MINI smart switch?

This switch takes a voltage-free switch circuit (i.e. your old switch cable(s), separated from the mains) across it's inputs S1 and S2. Any change of state of the light switch(es) will change the output of the device (along with its wi-fi control) so regardless of whether it is on or off, switching the switch will toggle it.

The problem is I'm finding this intermittent (the wi-fi switching is fine, but the S1/S2 switch sometimes does nothing). I've tried 3 different devices on 2 different 2-way switch circuits.

I suspect noise on the switch wires. Has anyone else had this issue? How was it resolved?

It is otherwise a remarkable little device, at a remarkably low price.

 

[Andy-1960]

It may be that the existing switch(es) is/are giving a poor connection when making due to the contacts being carbonised (or just poor quality) giving a high resistance connection when turned on. The electronics within the Sonoff unit will be low voltage low current. Might be worth trying a new good quality switch.

 

[1Justin]

I ordered one two months ago to try out. It has not arrived yet from China..
Provided you are sure you have the 2-way wired correctly, then It's probably just what you get for less than a fiver

The S1 S2 will be a very high impedance input, so there is hardly any conceivable way it would really care even if the switches you used were dangerously high resistance for mains low voltage (I'm imagining even in the hundreds of ohms ought to be fine).

I'll also add that on inspection of the Sonoff devices, it seems to me that even the "basic" (ie the original bigger torpedo shaped one) which looks like it should not need secondary containment, would do. The mains PCB sits directly within the plastic case, single layer. Hence it's neither Class 1 earthed metallic or class 2 double insulated. It is in fact Class 0 AFAICT. (I stand here to be corrected on that). - As such not suitable for the method of use intended (which is potentially exposed to touch, the cables clamped to the integral clamps).

Given the above, I have slightly cold feet about the general process which went into the design of these. I may well decide to put my DIY mini in an all-steel enclosure for safety if it ever arrives. (I'll ought to leak ok at the joints for 2.4GHz).

 

[PeakSteve]

It may be that the existing switch(es) is/are giving a poor connection when making due to the contacts being carbonised (or just poor quality) giving a high resistance connection when turned on. The electronics within the Sonoff unit will be low voltage low current. Might be worth trying a new good quality switch.

Done! (Replaced with Hager).
[automerge]1577610901[/automerge]

Done! (Replaced with Hager).

However, I have found that, when the device is non-responsive, flicking the switch ON/OFF/ON/OFF half a dozen times usually makes the device toggle. (This is what led me to think there might be noise on the wires that is confusing the device.)
P.S. One circuit is about 10m in length, driving 2 small LED panel lights, the other about 20m, driving 6 x LED GU10s - both behave in a similar way.
[automerge]1577611187[/automerge]

I ordered one two months ago to try out. It has not arrived yet from China..
Provided you are sure you have the 2-way wired correctly, then It's probably just what you get for less than a fiver

The S1 S2 will be a very high impedance input, so there is hardly any conceivable way it would really care even if the switches you used were dangerously high resistance for mains low voltage (I'm imagining even in the hundreds of ohms ought to be fine).

I'll also add that on inspection of the Sonoff devices, it seems to me that even the "basic" (ie the original bigger torpedo shaped one) which looks like it should not need secondary containment, would do. The mains PCB sits directly within the plastic case, single layer. Hence it's neither Class 1 earthed metallic or class 2 double insulated. It is in fact Class 0 AFAICT. (I stand here to be corrected on that). - As such not suitable for the method of use intended (which is potentially exposed to touch, the cables clamped to the integral clamps).

Given the above, I have slightly cold feet about the general process which went into the design of these. I may well decide to put my DIY mini in an all-steel enclosure for safety if it ever arrives. (I'll ought to leak ok at the joints for 2.4GHz).

I take your point re. insulation, but - to be fair - the MINI is small, and designed to be installed inside an enclosure, so this is not so much of an issue. (However, as you suggest, the wi-fi range may be somewhat compromised!)
I installed my 2 in the loft, inside a patress box (with blank plate lid)

 

[PeakSteve]

Update:
Sonoff have written back (ignoring my suggestion that either S1 or S2 is connected to Earth (the switch has no Earth reference otherwise, so one would merely be clamping one of the control wires to Earth to minimise any noise, IMHO) but suggesting I install "an Electrodeless capacitance between S1&S2". Presumably a non-electrolytic capacitor, but no indication of value!

They also say "We are developing a new plan to solve the problem, but it will take some time".

Still amazing value for money. I've even fitted one in place of a time switch, where the switch would otherwise have to be armoured!