eBay touch switch module (Patreon)

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Whether you should actually use a generic Chinese touch switch is debatable. They don't seem to fully understand electrical isolation much. A version sold by a prominent local supplier is more likely to be built to a safer standard. This module came with four wire nuts, which are rarely used in the UK. The bulk of the work on the PCB is being done by a dedicated chip that is not the typical microcontroller. It has dedicated circuitry including an amplifier and filter for the touch input and timing for the triac driver. The use of a capacitor in series with the triac gate is to keep the power supply simpler, as it results in a short trigger pulse of reasonable current. The data sheet for the chip has extra layers of safety on the touch input, both for the user and the chip. The extra components have been omitted in this design. The timing resistor is an odd value. Possibly a "safe" value for both 50 and 60Hz that ensures the triac trigger points are well within each half sinewave. The triac is very small. Its rating is a surprisingly high 600mA which suggests a typical lamp rating of 60W or much lower with LED lamps due to the high inrush current associated with their circuitry. The most common failure with dimmer modules like this is the triac going short circuit when a lamp fails with a pulse of high current. I specifically avoid using intrusive mid-run video adverts for a more relaxing viewing experience. If you enjoy these videos you can help support the channel with a dollar or two for coffee, cookies and random gadgets for disassembly at:- https://www.patreon.com/bigclive Patreon supporters get early access to advert-free videos as they are made, and also regular live streams. The Patreon support keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty. Other contribution options are available at:- http://www.bigclive.com/coffee.htm #ElectronicsCreators