Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: David Higton <dave@davehigton.me.uk>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: USB controlled mains switch
Date: Sun, 19 Jan 2025 17:35:32 GMT
Organization: Home
Lines: 35
Message-ID: <423fc3e15b.DaveMeUK@BeagleBoard-xM>
References: <TjgqpoLGRDjnFwvW@ku.gro.lloiff>
Injection-Date: Sun, 19 Jan 2025 18:35:42 +0100 (CET)
Injection-Info: dont-email.me; posting-host="a82c1766cd88f0ff4acde041d2d5fa02";
	logging-data="2521875"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+17N47rUHeUacilYHBlMObZsWUXq5fhc4="
User-Agent: Messenger-Pro/8.03 (MsgServe/8.01) (RISC-OS/5.31) NewsHound/v1.55
Cancel-Lock: sha1:8JxlJ/Y8wYEbbezpgWD4snWJ21k=
Bytes: 2503

In message <TjgqpoLGRDjnFwvW@ku.gro.lloiff>
          Adrian <bulleid@ku.gro.lioff> wrote:

> I'm looking for a USB controlled mains switch (230V AC) that I can  connect
> to a PI to turn a mains power supply on and off.
> 
> I've done a bit of digging around on the net, and 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).  The latter  appears to
> be in excess of 100Euros, which is considerably more than I  want to pay.
> 
> Any suggestions on where to look ?  I'm not interested in a wireless 
> solution, as it is likely to be used in places where signals are not 
> reliable.

I did a bit of searching around.  AliExpress sell various models of
USB mains-rated relay boards.  Various models offer 5V, 12V or 24V
operation.  I see from a later posting that your RPi is in an IP55
plastic box, so I'm jumping to the conclusion that you're happy with
a bit of DIY to turn it from a board into a solution.

If I were doing it this way, I think I'd go for a 12V powered board
and have a separate PSU, rather than burden the RPi's supply further
as many people have problems that are traceable to inadequate power
supplies.

It sounds like you may have to build a USB library for the relay
boards - I don't know.

If I were doing the overall job that you're doing, I wouldn't use
USB, I'd use a GPIO pin to switch a different relay board on/off.
Much easier (and I've done lots of work on USB firmware and drivers).

David