SONOFF DUAL as a "smart dimmer switch" for NON-dimmable LED bulbs

[@utubeanesh]

Thanks for sharing this nice idea. While changing from Low Brightness to High Brightness (Time stamp 8:30), first low switch must be openned and after few milliseconds High Switch must be closed. This will avoid short circuiting the capacitor's charge through the relay contacts. This circulating current will be high when capacitor is fully charged at +ve/-ve cycle's peak.

[@MyProjectBoxChannel]

The delay is a good idea and will definitely help to prolong the life of the relay contacts😉👍. In practice I didn't find it to be a problem in my case. I think the current spike is very short, and many types of lighting will have a big inrush current spike, similar to this.

[@utubeanesh]

That may be one of the reason for premature failure of latest smart relays and LED lights. No standards govern Inrush current limits 😢 Another issue: I really wonder why OEMs don't provide snubber when driving inductive loads. Everywhere miniaturization cost reduction etc...

[@MyProjectBoxChannel]

@@utubeanesh I do get what you are saying 🤔. I sometimes add a low value series resistor to the capacitor, in my circuits, to limit some of the inrush current. It really does help to protect the switch contacts from the "instantaneous" peak current. Something like 5 or 10 ohms. For bigger PSUs a NTC thermistor is better.

[@ladams5356]

Good hack. Now make the lights dim up from low to high over 2 secs please 👍👌

[@ketandeshpande8307]

Can you please post details abut capacitors . Any specific one needed

[@MyProjectBoxChannel]

It all depends on how bright or dim you require the lights to be. The amount of LED bubs in parallel, and the wattage of the bulbs will affect the brightness. More LED bulbs will be dimmer on the same capacitor. Make sure that all the bulbs are the same type and power. Maybe start with 1uF and go down to 0.22uF for testing 🤔?

[@calvinbrowne2126]

Neat hack.

[@JDSchuitemaker]

Living on the edge with the open connections on the capacitor at 110/220V, or am I missing something?

[@MyProjectBoxChannel]

It is possible to put the capacitor inside with the lid closed, however for the purposes of the video, it's left open so everything can be seen clearly. You could also enclose the sonoff dualR2 in a separate enclosure, if you prefer.

[@MrBobWareham]

Nice one, I wonder where you got the idea from, Bob in the UK