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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: relay modules?
Date: Thu, 11 Apr 2024 10:03:10 +0100
Organization: A little, after lunch
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On 10/04/2024 14:16, Chris Green wrote:
> Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:
>> Hi all. Two separate projects which will need a relay of some sort to
>> run from a Pi or similar.
>>
>> I'm really looking for something plug-and-go rather than build-your-own
>> (especially item 2 below)
>>
>> First is a dpdt relay to switch around 12-20 V at a couple of amps. spdt
>> are easy to come by; the only dpdt ones I've found are on aliexpress,
>> but their longevity is possibly open to question :-{
>>
> Try CPC (cpc.farnell.com), but you will probably need some sort of
> 'driver' between the Pi digital output and the relay coil.
> Alternatively, as suggested here, a solid state switch or even an opto
> isolator.
> 
> 
>> Second is something to switch mains safely - a full 13A to run a 3kW
>> heater. I've drawn a blank: best I can think of is to butcher one of
>> those wireless mains switch modules, which would at least provide a good
>> isolation gap :-)
>>
> Again CPC will probably have something, but again you'll need
> something between the Pi and the 'whatever'.
> 
> Are there not ready made relay modules for the Pi?
> 
There are, but most are lower power and SPDT.

Which is why I built my own...

BUT although it would be a fun project, even getting hold of big solid 
state relays is difficult.


-- 
"First, find out who are the people you can not criticise. They are your 
oppressors."
      - George Orwell