Remote control with mains referenced antenna

When I saw this on eBay I wondered if the chunky brass connector on the antenna was going to be referenced to the mains supply. It didn't disappoint. In the wrong circumstances it can impart a serious electric shock. (Especially if live and neutral are swapped.)
If you have one of these, be aware that it needs to be mounted fully inside a plastic enclosure.

Other than that fairly significant thing, the only other obvious issue is the parallel zener diodes, where series connection would spread the load better. They're also dissipating a significant amount of power. If using this module I would look at changing the dropper cap for a lower value one matched to the real current requirement of the circuit with relay activated (around 50mA). Keeping in mind that the hold current of the relay is lower than the initial pull in current.

If the supply is wired correctly, and the neutral is referenced to local ground, the potential on the antenna socket with respect to ground should be relatively low, but a reversed supply will allow a very high current shock. Basically the live feed, a diode and then you.

I missed one small detail off the schematic of the receiver. The button is wired between a microcontroller pin and the 0V rail.

It was only when I watched the video after recording it that I realised the F and N markings on the remote control are the last letters of off and on. I've never seen that before.

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