Sonoff Mini Optocoupler 2-way hotel switching

Automating the house is a lot easier if the woman is not bothered by it. Sonoff Mini helps with this and integrates the sonoff into the existing electricity installation. This result into a high WAF. The Sonoff-Mini has the option to connect an external switch. This means that the Sonoff can also be operated with the existing switches. Unfortunately, the existing wiring has to be adjusted. Often adapting the existing wiring is not an option. In most countries, electrical wiring is built into the wall. And although the wires are in tubes in the Netherlands, it is not desirable to adjust the wiring, because when selling the house, the original wiring must remain intact for the following residents.

Sonoff mini with sensor input

The input (S1 & S2) is intended for an external switch but appears to be connected to a GPIO of the EasP8266 with a pull-up resistor. This input can therefore be used for a sensor. In this project I use a simple light sensitive resistor to switch the lamp on and off.

DIY Optocoupler

The first prototype was with a single rectifier (and therefore with half light) but did not work well enough. The prototype is made of old components and works well.

Be aware of the high voltage! I used heat shrink tubes to isolate the circuit and to connect the LED to the LDR.