Subj : Re: USB controlled mains switch
To   : All
From : R.Wieser
Date : Sun Jan 19 2025 20:24:56

Adrian,

> ... the options seem to fall into two categories, either a relay device
> which means having to rewire the device (which I'd rather avoid), priced
> around 30Euros or one that sits in line (between the device and the
> supply)

Whut ?   As others have already mentioned, you could take a short extension
cord and put the relais* in that cord.  Makes it reusable too.

* also consider a solid-state relais.

Also, you say USB controlled.  How do you imagine that ?  As some kind of
special USB device (for which it is hard to find a driver) ?

Perhaps consider a simple USB-to-serial thingly*, where you can use the DTR
line to signal the relais board to switch on.  After that you can use the
RPi build-in serial API to switch the relais.

* I would strongly suggest to use one of RPi's gazillion I/O pins for it,
but as you specifically mentioned USB controlled ...

The only thing you will need to do (and which costs money) is to put the
relais (and the USB-to-signal-line thingamagochy ?) in a shielding plastic
box.  220 is lethal even when you touch it by accident. :-)   And make sure
the 220v and the relais-driving low-voltage electronics are well seperated.
Your RPi doesn't like 220v either. :-o

Regards,
Rudy Wieser

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