Modifying Tuya Mini for No-Neutral Installation: Experiences with Diode Polarity Reversal?

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How can I wire a Tuya/Aubess mini relay for no-neutral operation so the wall switch on S1/S2 still toggles the relay without the module going offline?

Yes, but the thread says your current polarity change is not enough: with that configuration T1 stays on and S1-S2 stay closed, so you need to reorient D5, C1 and D6 so T1 turns off and S1-S2 open when SW1 is open [#20529187] The practical consequence of the simpler diode reversal is that the mini works, but it loses connection when the wall switch is off; in that setup you only get remote control when the wall switch is closed [#20526471] The switch input also needs to be configured in Toggle mode for S2 [#20523207] After the final reconfiguration, spin55 reported that “it works with this assembly,” and the original poster confirmed the working diagram [#20531832]

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#31 20534937 11 Apr 2023 18:25

spin55 spin55

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Post #31
20534937 11 Apr 2023 18:25

ferbulous wrote:
@spin55 thanks for the successful test & the working diagram!
I think I’ll move to using cables this time instead of pcb and redo this again

Thank you for the links to those interesting videos.

p.kaczmarek2 wrote:
@spin55 very good job, you should post it separately to Smart Home Tutorials section with a better description (in a form of tutorial) and get a free gift:

Thanks. I'll try but I don't promise you anything. My wife threatens me with divorce every time I take over the kitchen room to take videos or photos.

Regards
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#32 20536016 12 Apr 2023 12:44

ferbulous ferbulous

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Post #32
20536016 12 Apr 2023 12:44

@spin55 what's your opinion on using this hack with ceiling fan? could it be used?
I think the channel mention that it depends on the fan itself if it can be powered by half wave dc.
I have these ones at home, one with a knob speed controller and another using remote
#33 20536172 12 Apr 2023 14:34

spin55 spin55

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Post #33
20536172 12 Apr 2023 14:34

All the assembly would be valid, except that it would be necessary to "play" with these three components. How many watts does it consume?
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Estimated motor wattage from Tuya Mini specs
#34 20536194 12 Apr 2023 14:47

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Estimated motor wattage from Tuya Mini specs
Post #34 20536194 12 Apr 2023 14:47

spin55 wrote:
All the assembly would be valid, except that it would be necessary to "play" with these three components. How many watts does it consume?

I might need to get the tuya mini with power monitoring to verify the wattage
According to the specs sheet, these are the estimates

Motor W : Low 14.1 – 19.9
High 67.5 – 82.5
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#35 20536220 12 Apr 2023 15:04

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Post #35
20536220 12 Apr 2023 15:04

Do you know that you can control it remotely with SW Closed and this configuration?:
#36 20536279 12 Apr 2023 15:52

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Post #36
20536279 12 Apr 2023 15:52

spin55 wrote:
Do you know that you can control it remotely with SW Closed and this configuration?:

This would require neutral behind the switch, correct? And you'd need to lock the switch in always on position
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#37 20536339 12 Apr 2023 16:32

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Post #37
20536339 12 Apr 2023 16:32

ferbulous wrote:
And you'd need to lock the switch in always on position

This is correct, but the neutral wire is already in the ceiling.

This is how I have ceiling lights in my house.
Neutral already present in ceiling wiring
#38 20536356 12 Apr 2023 16:50

ferbulous ferbulous

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Neutral already present in ceiling wiring
Post #38 20536356 12 Apr 2023 16:50

spin55 wrote:

ferbulous wrote:
And you'd need to lock the switch in always on position

This is correct, but the neutral wire is already in the ceiling.

This is how I have ceiling lights in my house.

I see, so this is another alternative just that it turns off openbk if the switch is toggled off.
And that startup command turns on the relay once it boots up, and remote control is back.
I have a 2 way switch that controls a ceiling fan which I'm still figuring out if it's safe to use the hack
Clarifying two-way switch use for fan control
#39 20536416 12 Apr 2023 17:40

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Clarifying two-way switch use for fan control
Post #39 20536416 12 Apr 2023 17:40

ferbulous wrote:
I see, so this is another alternative just that it turns off openbk if the switch is toggled off.
And that startup command turns on the relay once it boots up, and remote control is back.

OK

ferbulous wrote:
I have a 2 way switch that controls a ceiling fan which I'm still figuring out if it's safe to use the hack

Two ways for what? One for light and one for fan?. Doesn't control light and fan with remote control? If so, you only need one way.

Regards
#40 20536534 12 Apr 2023 18:54

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Post #40
20536534 12 Apr 2023 18:54

spin55 wrote:
Two ways for what? One for light and one for fan?. Doesn't control light and fan with remote control? If so, you only need one way.

Separate lights and fan, just that each have 2 way wiring
#41 20536620 12 Apr 2023 19:43

spin55 spin55

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Post #41
20536620 12 Apr 2023 19:43

Mini switch for fan. Same thing if you want individual manual control of each light. Same assembly as before but you would need a mini switch for each line.
#42 20536689 12 Apr 2023 20:10

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Post #42
20536689 12 Apr 2023 20:10

spin55 wrote:
Same assembly as before but you would need a mini switch for each line.

yes, that's what I plan to do with all the lights
I'm just not sure if it's safe to use the hack for the ceiling fan, I mean would it affect the fan motor or something since it's using half wave dc
Proposed fan-safe rectifier assembly for the hack
#43 20536819 12 Apr 2023 23:57

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Proposed fan-safe rectifier assembly for the hack
Post #43 20536819 12 Apr 2023 23:57

ferbulous wrote:
I'm just not sure if it's safe to use the hack for the ceiling fan, I mean would it affect the fan motor or something since it's using half wave dc

With this assembly you should not have a problem with the fan:

Forget about this assembly, because as you say, it works with pulsating direct current and needs alternating current to work. And you can't suppress the diode because it would blow up the electrolytic capacitor. Thanks for making me see. what a mistake.

Don't even try it because the impedance of the motor winding is too small in DC, it may damage the fan!!!

Added after 2 [hours] 36 [minutes]:

I think this assembly might work with the fan:
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#44 20537878 13 Apr 2023 16:17

spin55 spin55

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Post #44
20537878 13 Apr 2023 16:17

spin55 wrote:
I think this assembly might work with the fan:

I did tests with a hand dryer because I don't have a fan and I can confirm that this setup only works when the wall switch is closed. AC devices do not work with a single half cycle.

https://www.elektroda.com/rtvforum/topic3971605.html#20537876

Regards
Half-wave DC only works with DC loads
#45 20538103 13 Apr 2023 18:34

ferbulous ferbulous

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Half-wave DC only works with DC loads
Post #45 20538103 13 Apr 2023 18:34

spin55 wrote:

spin55 wrote:
I think this assembly might work with the fan:

I did tests with a hand dryer because I don't have a fan and I can confirm that this setup only works when the wall switch is closed. AC devices do not work with a single half cycle.

https://www.elektroda.com/rtvforum/topic3971605.html#20537876

Regards

Thanks for the detailed explanation on how it works with dc or ac
From your test, the hand dryer (ac) didn’t turn on when the relay is toggled on with half wave dc (switch in open position).
So if my fan is using dc motor, then technically half wave dc could still power the motor as normal with no issues?

Also, since you’ve excluded the fusible resistor in the diagram with fan, is it advisable to do that since the youtube channel did mention fusible resisor is needed for safety reason
Half-wave DC fan supply with diode and capacitor sizing
#46 20538272 13 Apr 2023 20:23

spin55 spin55

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Half-wave DC fan supply with diode and capacitor sizing
Post #46 20538272 13 Apr 2023 20:23

ferbulous wrote:
o if my fan is using dc motor, then technically half wave dc could still power the motor as normal with no issues?

In my opinion, I would only have to choose the diodes D1 and D7 based on the consumption in amps of the load.
The rest would be the same as the devices that have power supplies that are connected to AC but internally work with DC. That's why I think that the DC fan could work by "playing" with the diodes and the value of C2, increasing it if the ripple is excessive.

These are the characteristics that you have to pay attention to when choosing the diodes:

ferbulous wrote:
Also, since you’ve excluded the fusible resistor in the diagram with fan, is it advisable to do that since the youtube channel did mention fusible resisor is needed for safety reason

It's right, all assemblies should have a protection fuse for safety reason!!.

Resistor R3 is there to protect D7 when you plug the entire assembly into the mains AC for the first time. At that instant the capacitor is discharged and there is a significant current peak that must not exceed the maximum supported by D7. It also protects if there is an excessive consumption of C2 or fan due to failure. During the negative half-wave, D7 acts as a switch and prevents C2 from being destroyed which begins to discharge through the fan by supplying it with the current it needs. This is repeated every 10 milliseconds (for a mains frequency of 50Hz) and the set of C2 and fan impedance have to make C2 hold as much charge as possible.

NOTE: Before trying the assembly 4 with DC fan I would make sure what type of internal power supply it has.

NOTE2: Please, if someone is not sure what it does, don't try it. This can be dangerous for people if they don't understand what they are doing and why.

Regards
#47 20539610 14 Apr 2023 18:32

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Post #47
20539610 14 Apr 2023 18:32

spin55 wrote:
NOTE: Before trying the assembly 4 with DC fan I would make sure what type of internal power supply it has.

Hi, how do I check for the internal power supply? Any specific ones I need to look out for

spin55 wrote:
These are the characteristics that you have to pay attention to when choosing the diodes:

Since i'm already using IN4007 diodes, would that be sufficient?

spin55 wrote:
Resistor R3 is there to protect D7 when you plug the entire assembly into the mains AC for the first time. At that instant the capacitor is discharged and there is a significant current peak that must not exceed the maximum supported by D7. It also protects if there is an excessive consumption of C2 or fan due to failure. During the negative half-wave, D7 acts as a switch and prevents C2 from being destroyed which begins to discharge through the fan by supplying it with the current it needs. This is repeated every 10 milliseconds (for a mains frequency of 50Hz) and the set of C2 and fan impedance have to make C2 hold as much charge as possible.

Thanks for the detailed explanation
Test C2 with UF5408 diodes and K15V0 fan
#48 20540862 15 Apr 2023 15:50

spin55 spin55

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Test C2 with UF5408 diodes and K15V0 fan
Post #48 20540862 15 Apr 2023 15:50

ferbulous wrote:
Since i'm already using IN4007 diodes, would that be sufficient?

Yes, to check how many watts you can handle with that value of C2 with the test of accumulating light bulbs.
1.- SW1 in open position and remotely controls the relay from the web.
2.- Add another bulb in parallel and keep adding bulbs until they blink.
3.- You will already have a reference of the watts that you can control with those components.
----------------------------
I used UF5408 diodes instead of 1N4007 because it was what I had to do the test.
With these diodes and a value of 470uF/450V for C2, I would test the model K15V0 fan.

ferbulous wrote:
Hi, how do I check for the internal power supply? Any specific ones I need to look out for

If you are sure that the fan is DC, don't worry, you can connect it without fear.
Do the test with C2 (470uF/450V), D1 and D7 (UF5408) and Fan model K15V0.
Half-wave supply may keep ESP8266 powered
#49 20542441 16 Apr 2023 15:26

ferbulous ferbulous

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Half-wave supply may keep ESP8266 powered
Post #49 20542441 16 Apr 2023 15:26

spin55 wrote:
Do the test with C2 (470uF/450V), D1 and D7 (UF5408) and Fan model K15V0.

I can't quite confirm yet if the fan that comes with speed regular (K15V0) is using dc motor, I do believe the remote controlled fan model is using ac

spin55 wrote:
If you are sure that the fan is DC, don't worry, you can connect it without fear.

what's the worst that could happen if tested with AC device ? seems like from your testing with ac hair dryer, the device just doesn't turn on with half wave

Considering the circuit is still powered by half wave when the switch is off position (half wave dc only), could i use that so it always powers the esp8266?
Half-wave supply can keep ESP8266 powered
#50 20542515 16 Apr 2023 16:20

spin55 spin55

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Half-wave supply can keep ESP8266 powered
Post #50 20542515 16 Apr 2023 16:20

ferbulous wrote:
Considering the circuit is still powered by half wave when the switch is off position (half wave dc only), could i use that so it always powers the esp8266?

Yes

ferbulous wrote:
I can't quite confirm yet if the fan that comes with speed regular (K15V0) is using dc motor, I do believe the remote controlled fan model is using ac

With this assembly:

1.- SW1 Closed. Relay On via web. It should work.
2.- SW1 Opened. Relay On via web. If there is movement it is Fan DC.

Do the same for the other fan if you want to compare.
Suggested test setup for comparing fan movement detection
#51 20543240 16 Apr 2023 23:00

ferbulous ferbulous

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Suggested test setup for comparing fan movement detection
Post #51 20543240 16 Apr 2023 23:00

spin55 wrote:
Yes

Awesome, I have some diy mmwave sensors that could really benefit from this, just have it hidden away in the ceiling under the light fixtures

spin55 wrote:
With this assembly:

1.- SW1 Closed. Relay On via web. It should work.
2.- SW1 Opened. Relay On via web. If there is movement it is Fan DC.

Do the same for the other fan if you want to compare.

Thanks for the instructions, i'm gonna start small with the stand fan first
Wouldn't want the wife to get angry if the ceiling fan stops working
Diode polarity test for Aubess mini switches
#52 20745181 24 Sep 2023 12:08

franfj franfj

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Diode polarity test for Aubess mini switches
Post #52 20745181 24 Sep 2023 12:08

This is a great idea. I've successfully used it on Aubess mini switches.

The easy way to start is with just a diode in series in the Line In, noting the polarity which powers on the mini-switch, and build the rest of the circuit according to that polarity.

I wonder if it's better to always put the 400V capacitor near the bulb, or avoid it if the light does not blink? Not having the capacitor allows to put it in small spaces.
Capacitor only needed to prevent half-cycle flicker
#53 20746946 25 Sep 2023 18:44

spin55 spin55

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Capacitor only needed to prevent half-cycle flicker
Post #53 20746946 25 Sep 2023 18:44

franfj wrote:
I wonder if it's better to always put the 400V capacitor near the bulb, or avoid it if the light does not blink? Not having the capacitor allows to put it in small spaces.

Logically, if the bulb does not blink without a capacitor, you don't need to put it in.

The reason for putting the capacitor is so that the bulb does not flicker during the negative half cycle of the mains wave. The diode acts as a switch that only conducts during the positive half cycles and recharges the capacitor. During the negative half cycle, the diode does not conduct and the capacitor keeps the light bulb on during the 10 milliseconds that the wave lasts (for a 50Hz network).

It could remove the capacitor if the mains frequency increases. In this case, you could also remove the diode and the protection resistor. The light bulb would turn off during the negative half cycle, but we would not perceive it due to the persistence of images on the retina.

Greetings
10R fusible resistor sizing for lamp load
#54 20772394 16 Oct 2023 12:46

franfj franfj

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10R fusible resistor sizing for lamp load
Post #54 20772394 16 Oct 2023 12:46

Sounds logical.

Any recommendations for the 10R fusible resistor? I tried with one of 1/2W and worked for about a month, but it got fused. Maybe it was a bad quality resistor, or maybe it was not well calculated.

The theory is that this resistor gets a lot of power for a short time during the power on because of charging the capacitor, but since all the power for the LED lamp passes through it, it must also be able to dissipate the corresponding current.

In my calculations, 1/4W for 10R should be enough for up to 30W lamp, 1/2W for up to 50W lamp, am I right?
Resistor power calculation for no-neutral LED load
#55 20772829 16 Oct 2023 19:13

spin55 spin55

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Resistor power calculation for no-neutral LED load
Post #55 20772829 16 Oct 2023 19:13

The 50W of the LED lamp refers to a given alternating current supply and a cosine of phi, so P=V.I.cos phi.

There you could calculate the effective current intensity consumed by the lamp, which would be I=P/(V.cos phi). For a mains voltage of 230V/50Hz and a cosine of phi=1, the current would be 0.227A.

Therefore, the power dissipated in the resistor would be P=I(squared).R, which would result in 0.515W. But the electrical voltage allows a variation margin of +-10%, therefore you must always allow for excess. In this theoretical case I would try a resistor of 1W or the nearest standard value.

But you will see in the videos that here we are not applying an alternating current and therefore the voltage and current calculations differ.

https://www.youtube.com/watch?v=sekdEc5wU6k
https://www.youtube.com/watch?v=J8lNkVzukSM

Greetings
#56 20775066 18 Oct 2023 13:13

franfj franfj

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Post #56
20775066 18 Oct 2023 13:13

Right, that's the formula that I've used. I forgot the 10% variations on 230V... and I didn't remember well the power of my LED lamp, I thought it was 40W but after checking, it was actually 55W so 1/2W is clearly not enough.
#57 20824558 20 Nov 2023 15:26

franfj franfj

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Post #57
20824558 20 Nov 2023 15:26

If anyone wants to try the new circuit https://youtu.be/mznx0xoF8Ck?feature=shared

The fusible resistor placement is changed to support more power-hungry LEDs.
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#58 20894879 06 Jan 2024 20:01

MyProjectBox MyProjectBox

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Post #58
20894879 06 Jan 2024 20:01

>>20531832
Hi I'm the author of the NO-NEUTRAL circuit youtube video, for the Sonoff mini-R2. I'm sorry to see this discussion so late 😪. I could of helped to clarify some things. I appreciate all the good work you are doing. I might do a youtube video a tuya mini NO-NEUTRAL circuit, if you don't mind?

Added after 12 [minutes]:

@franfj have you tried my new NO-NEUTRAL circuit yet?
Offer to help with OBK flashing guide and schematics
#59 20894932 06 Jan 2024 20:20

p.kaczmarek2 p.kaczmarek2

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Offer to help with OBK flashing guide and schematics
Post #59 20894932 06 Jan 2024 20:20

That's a great video, @MyProjectBox ! I haven't personally tried it because I am lucky enough to have both L and N wires routed to switches in my house, but I am confident that many houses in Poland don't have N available so your no-neutral mod will certainly come useful for our users.

By the way, if you are interested in making some kind of OBK-related video (flashing guide or something), let me know, I can help with that, maybe even provide schematics or other media.

Added after 40 [seconds]:

We can feature your video on our page if you're interested:
https://openbekeniot.github.io/webapp/devicesList.html

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
#60 20895043 06 Jan 2024 21:11

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Post #60
20895043 06 Jan 2024 21:11

MyProjectBox wrote:
>>20531832
Hi, I'm the author of the NO-NEUTRAL circuit YouTube video for the Sonoff mini-R2. I'm sorry to see this discussion so late 😪. I could have helped to clarify some things. I appreciate all the good work you are doing. I might do a YouTube video on the Tuya mini NO-NEUTRAL circuit if you don't mind?

Added after 12 [minutes]:

@franfj have you tried my new NO-NEUTRAL circuit yet?

Not yet, but I have a project in mind to use it.

Thanks for sharing it!
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Topic summary

✨ The discussion centers on modifying Tuya Mini and similar smart switches (e.g., Aubess mini, Sonoff Mini-R2) for no-neutral wire installations by reversing diode polarity and adjusting associated components. Key modifications include flipping the 1N4007 diodes and electrolytic capacitors, especially those connected to the optocoupler, to ensure conduction during the positive half-wave of the AC mains. The relay toggle functionality from wall switches (S1 & S2) is problematic when the relay is off, requiring further circuit tuning such as adjusting RC network resistor values (e.g., increasing from 56K to 100K) to maintain relay activation. Safety improvements involve using fusible resistors placed near capacitors to handle inrush currents during capacitor charging. The no-neutral hack is effective for lighting loads but may not suit AC motors or fans due to half-wave DC supply potentially damaging motor windings; DC fans may work if diode ratings and capacitor values are adjusted accordingly. Testing with loads like hand dryers confirmed AC devices fail to operate properly on half-wave DC. The community shared detailed wiring diagrams, component value calculations, and practical test results, including current through optocoupler LEDs (~1.14 mA) and resistor power dissipation estimates. The discussion also covers alternative wiring setups with neutral at the ceiling, remote control integration, and the impact of switch configurations on relay behavior. The original no-neutral circuit author offered to provide updated designs and tutorials. Overall, the thread provides a comprehensive technical exploration of no-neutral smart switch modifications, component selection, safety considerations, and load compatibility.
AI summary based on the discussion. May contain errors.

FAQ

TL;DR: For 230 V, 50 Hz Tuya/Aubess no-neutral installs, the tested fix is “It works with this assembly”: align diode/capacitor polarity with the mini switch, add an optocoupler trigger, and keep the load circuit protected by a fusible resistor. This FAQ is for smart-switch modders solving S1/S2 relay-toggle failure at the light fixture. [#20531832] Why it matters: A wrong half-wave polarity can keep the module online while leaving the wall switch unable to toggle the relay.

Alternative	Result in the thread	Practical limit
Sonoff-style original polarity	Tuya Mini did not boot on the first attempt	Needs polarity adaptation
Reversed diode for Tuya/Aubess	Mini switch powered on	S1/S2 trigger still needed
Tested optocoupler assembly	Wall switch and remote control worked	Requires careful mains wiring
Simple series wiring	Manual works; remote works only with switch ON	Module goes offline when switch OFF

Key insight: The Tuya/Aubess version is not just a diode swap. The optocoupler trigger must open and close S1/S2 at the correct half-cycle, while the mini switch stays powered.

Quick Facts

The tested optocoupler input used measured resistors of 45.9 kΩ and 46.9 kΩ, with 1.1 Vdc on C1 and 1.14 mA current. [#21406579]
At 236 Vac mains, the peak voltage was calculated as 332 Vac, and Vdc was estimated as Vp/π, or 105.73 Vdc. [#21406579]
A 10 Ω fusible resistor at 50 W and 230 V with cos φ = 1 dissipates about 0.515 W, so a 1 W part was suggested. [#20772829]
The bulb-side capacitor was discussed as 400 V, and one tested fan/load circuit used C2 = 470 µF / 450 V. [#20540862]
For 50 Hz mains, the capacitor near the bulb bridges the 10 ms negative half-cycle to reduce visible flicker. [#20746946]

How can I modify a Tuya or Aubess mini switch for a no-neutral installation at the light fixture?

Use the tested Tuya/Aubess adaptation with a series diode, bulb-side smoothing parts, and an optocoupler trigger for S1/S2.

Find the diode polarity that powers the mini switch.
Build the rest of the half-wave circuit to that polarity.
Add the optocoupler circuit so the wall switch pulses S1/S2. One user later confirmed the idea worked on Aubess mini switches. [#20745181]

Why does reversing the diode polarity make a Tuya Mini boot in a no-neutral circuit but stop S1 and S2 from toggling the relay?

Reversing only the power diode can feed the Tuya Mini but leave the optocoupler biased wrong. In that state, the wall switch changes the bulb path, not the relay input. The reported failure was precise: relay ON allowed bulb control, but relay OFF blocked wall-switch triggering. The trigger transistor stayed in the wrong state until D5, C1, and D6 were turned. [#20529187]

Which diodes and capacitors need to be flipped when adapting the Sonoff Mini R2 no-neutral hack for a Tuya or Aubess mini switch?

Flip the diode and capacitor around the bulb path, plus the optocoupler-side polarity parts. The thread specifically named D5, C1, and D6 for correction, so T1 turns OFF and S1/S2 opens when SW1 opens. If C1 is polarized, its polarity matters because reversing it incorrectly can damage the capacitor. [#20530029]

How do I test whether shorting S1 and S2 manually will trigger the relay in a modified Tuya Mini no-neutral setup?

Momentarily bridge S1 and S2 with a wire after the relay is turned off by the module button. Do not hold the short. First test with the optocoupler still connected. If the relay does not switch, disconnect S1 and S2 from the optocoupler, then repeat the momentary bridge. This separates firmware/input failure from trigger-circuit failure. [#20527813]

What OpenBeken pin configuration should I use for S2 on a Tuya Mini when the wall switch should toggle the same relay channel?

Configure S2 on the same relay channel, using Toggle mode or the tested OpenBeken options for that channel. The user had S2 on pin 14 and tested both toggleonchannel and btn_n. The mini push button and S2 were also assigned to the same channel. That setup removed channel mismatch as the main fault. [#20525635]

Why does the wall switch only control the bulb when the Tuya Mini relay is already on in this no-neutral circuit?

The wall switch only controls the bulb because S1/S2 is not receiving a valid trigger pulse. With the relay ON, the bulb path exists, so toggling the wall switch changes the lamp. With the relay OFF, the bulb remains off and the relay never changes state. The thread traced this to an optocoupler trigger state problem, not OpenBeken alone. [#20526372]

What is an optocoupler and why is it used between the wall switch circuit and S1/S2 on a Tuya Mini?

An optocoupler lets the wall-switch half-wave circuit trigger S1/S2 without directly joining the mains-side circuit to the module input. “Optocoupler is an isolation component that transfers a signal using light, keeping input and output electrically separated while allowing a low-current LED side to control a transistor side.” The tested circuit used about 1.14 mA through that input. [#21406579]

What is a fusible resistor and why is it recommended for safety in no-neutral smart switch hacks?

A fusible resistor limits current and opens under fault conditions instead of acting like ordinary wire. “Fusible resistor is a safety resistor that carries normal circuit current, limits surge current, and is designed to fail open during overload, reducing fire risk compared with a standard resistor.” The video author emphasized fusible resistors, and the thread later stated all assemblies need fuse protection. [#20538272]

How do I choose the wattage for a 10 ohm fusible resistor in a no-neutral LED lighting circuit?

Calculate resistor power from lamp current, then add margin for mains tolerance. For a 50 W LED at 230 V and cos φ = 1, current is 0.227 A. A 10 Ω resistor then dissipates 0.515 W. Because mains can vary by ±10%, the suggested practical choice was 1 W or the nearest standard value. [#20772829]

When can I omit the 400V capacitor near the bulb in a no-neutral Tuya Mini or Aubess Mini installation?

You can omit the 400 V capacitor when the bulb does not visibly blink without it. The capacitor exists to keep the lamp on during the negative half-cycle. At 50 Hz, that gap lasts about 10 ms. If the lamp driver hides that flicker, the capacitor is not required and space improves. [#20746946]

Tuya Mini vs Sonoff Mini R2: what changes are needed when using the Sonoff no-neutral circuit on Tuya or Aubess hardware?

Tuya/Aubess hardware needs polarity matched to the module, not copied blindly from Sonoff Mini R2. The first Tuya attempt using the Sonoff arrangement did not boot. Reversing polarity powered the Tuya Mini, then the optocoupler trigger still needed correction. A later practical tip was to start with one series diode in Line In and build the circuit from the working polarity. [#20745181]

Can a no-neutral half-wave circuit safely power a ceiling fan, and how does the answer change for AC motor vs DC motor fans?

Do not run an AC fan motor from the half-wave DC load circuit. The thread warned that motor winding impedance is too small in DC, so damage can occur. A DC fan may work if its internal supply suits the circuit, but the diodes and C2 must match load current and ripple. One discussed fan range was 14.1 W to 82.5 W. [#20536819]

What diode ratings should I use instead of 1N4007 or UF5408 for higher-power loads in a no-neutral smart switch circuit?

Choose diodes by load current and voltage, not by the mini-switch name. The thread used 1N4007 in small tests and UF5408 because those parts were available. For larger loads, select D1 and D7 from the fan or lamp current in amps. One proposed test used UF5408 with C2 = 470 µF / 450 V. [#20540862]

How can I check whether a ceiling fan uses an AC motor or DC motor before connecting it to a half-wave no-neutral circuit?

Use the relay test described in the thread before committing the ceiling fan. With SW1 closed and relay ON by web control, the fan should run normally. Then open SW1 and turn the relay ON by web control. If there is movement in the half-wave state, the fan behaves as a DC fan in that test. [#20542515]

What are the safety risks of building a no-neutral Tuya Mini modification inside a wall box or ceiling fixture?

The risks include mains shock, overheated resistors, damaged capacitors, and damaged AC motor loads. The circuit works directly around 230 Vac mains and peak voltages near 332 Vac were measured. One expert warned that major wiring interference may not be safe. Another warned: “don’t try it” if you do not understand what the circuit does. [#20538272]

AI summary based on the discussion. May contain errors.