[Swansea Hackspace] Isolating Solid State Relay

[Alan Cox]

On Tue, 29 Sep 2020 11:56:53 +0100
Neil Jones <neil at aurinia.co.uk> wrote:

> On 28/09/2020 16:38, Alan Cox wrote:
> > On Mon, 28 Sep 2020 15:55:41 +0100
> > Ceri Clatworthy <ceri.clatworthy at gmail.com> wrote:
> >  
> >> Should really be EARTHED !!!!!!
> >>
> >> especially for TESTING.
> >>
> >> Medium Aluminium box  
> > Ditto for noise reduction unless the SSR being used is a zero cross
> > switching SSR (these only switch when the AC is at the crossing point so
> > avoiding noise spikes from chopping a 300v+ peak to zero fast)
> >
> > Alan  
> 
> Thanks Ceri and Alan. I hadn't thought about the noise issue.  I had 
> come across zero cross switching as it is an issue for control by rapid 
> switching PWM stuff but it isn't a concern for me. That is very useful.

If you don't have a zero crossing SSR you not only want a box you also
should have something to damp the noise or it'll be all over your 5v and
12v signals. Normally you'd use metal oxide varistors or a transient
voltage suppressor of some kind.

Alan