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From: Chris Elvidge <chris@internal.net>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: USB controlled mains switch
Date: Sun, 19 Jan 2025 22:06:38 +0000
Organization: A noiseless patient Spider
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On 19/01/2025 at 19:24, R.Wieser wrote:
> 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) ?

As I have said previously, it's easy. E.g.
https://www.amazon.co.uk/Control-Intelligent-Channel-Controller-Support-default/dp/B07PWPF2DT
Load 'usbrelay' to control (apt-get install usbrelay')

> 
> 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
> 
> 



-- 
Chris Elvidge, England
I CANNOT ABSOLVE SINS