Another mains controller…

I’ve designed and built a few control boards for switching on mains (e.g. this and this), because it tends to be a thing that many of my projects need. Good (and good looking!) mains switches are hard to come by, especially for higher currents, so it makes sense to use a lower-voltage switch combined with a relay or an SSR for this duty. An obvious downside to the relay-based approach is that a standby voltage is needed to control the relay, but as described in a previous post there are now several types of switching AC-DC converters able to do that job very cheaply and reliably.

However, more often than not I have found that I prefer to keep the standby PSU separate and so this addition to the control-board portfolio was delberately made smaller and to fit my usual 2”x2” format to make it stackable with my softstart-board. For anything with a large transformer in it, this is a combination that is very useful.

Another addition is an external trigger input (isolated with an optocoupler) which I don’t often use to be honest, but which I could see some potential in anyway. To make this feature a bit more versatile I have opted for the “deluxe-version”, by feeding the optocupler from a constant-current source made from an LM317L. This should mean that it’s not just the usual “12V-trigger” input, but actually it would work with any voltage between app. 3-30V and draw less than 20mA from the triggering device.

“In flight” (or at least on the way) are boards for a matching standby PSU based on the Mean Well IRM power modules – when everything is here and tested I’ll publish some files and more pictures 🙂


One Response to Another mains controller…

  1. Pingback: Project files: A smaller mains controller… | theslowdiyer

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