Powering studio gear via SS relays

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Rob Flinn

Rob Flinn

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Joined
Jun 3, 2004
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5,273
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Between Sussex, UK & Aude, France.
Just wondered if anyone knew whether using mains voltage SS relays make the power dirty ?  I'm guessing there is some sort of triac in them.

The reason I'm asking is because I was thinking of making a sequential Power on/off unit using an Arduino so I don't have to go through my contortionist routine reaching behind racks to turn everything on & off in the right order.  Getting a bit old to reach some of the mains switches easily.

This sort of thing

https://www.ebay.co.uk/itm/DC-AC-Solid-State-Relay-SSR-40DA-Output-AC-24-380V-1-10Pcs-UK-Shipping/253460914266?hash=item3b0372a05a:m:myq_ugtlX6gDH2jt1QAwELA
 
I would guess it to switch at very low voltage so also be low current and not cause much RF, but the devil is always in the details. Can you try one and see?

JR
 
I guess I have one lying around somewhere.    They are quite good in that you can switch them on with as little 3v & the current is hardly anything.  The Arduino digtal outs could probably do it direct although probably better to use an opto isolator.

What is the best way to measure the noise ? 
 
Thanks Gus

It's true they don't turn off.  I remember that I was always reading 230v & thought that the relay was broken but in reality it just severely limits the current.  I was testing the relay with a Houselhold lamp plugged into it & although the lamp was switching on & off I could seemed to be able measure the full a.c volats on the relay in either state.  The articles that you link to seem to show ways around this but I think in reality the current must be so small as to not worry about it.  What do you think ?
 
I'd try a 230Vac to 12Vac transformer that is switched via the SSR, and measure the 12ac perfomance with scope and other test if needed. I'd also put a lamp on the swiched side of the SSR to provide as a load. I fiddled with a 50 Hz tracking notch filter for this sort of thing, but it was many decades ago
 
I have to do a similar routine powering things on and off. What about just a rackmount multi switch box to run everything too? Then sequential becomes pretty easy.
 
I also played witha LM3914 led bargraph driver, with the drivers feeding  SSRs. With a suitable DC ramp control ( RC network) voltage stuff could power up in a friendly order. It solved some power up current surge problems by staggering switch on over a second or so
 
john12ax7 said:
I have to do a similar routine powering things on and off. What about just a rackmount multi switch box to run everything too? Then sequential becomes pretty easy.
Click to expand...

I guess.  I suppose it's because I've been messing with some Arduino programming recently & it's not that difficult to do + I can go make a tea while it's powering up .....

I think the SSR's are not a bad way to do this.  Especially on things like my plate reverb, where  I could even run the control signal like phantom power, superimposed on one of the audio cables how the BBC used to do it.
 
Why not use an array of mechanical arrays?
Even cheapies are worthy for a few hundred thousand switches.

There's a good AVE video on youtube where we tests alibaba relays to their limits.
https://www.youtube.com/watch?v=ftJ17Cp6itw

 
Is this legal in UK?
I remember a similar sequencer/switcher from Elektor many years ago which was poo-poo'd in UK.
At CBS London, we did it with RS timer relays.; s"d all this programming.
 

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