Not so DIY - DIY external Temp Controller

[alons]

I would say, safety first, larger dedicated relay with bigger contacts is safer for 220v switching, while the internal controllers relays can switch 12v, which also prolong the controllers life. I've built several of those boxes, typically using the STC1000, which is a cheap temp controller (I always buy 2 and keep one for backup as sometime this controller is misbehaving). This controller can work with 12v or 220v input voltage, go with the 12 if you choose this model. More reliable controllers would cost $150+, but will give you a peace of mind. In the pic above, you can see the controller, 12v internal power supply, leds (hot/cold indicators), on/off switch, 2x12v relay for 220 switching (1 hot 1 cold), fuse (always put when dealing with 220v).
Hope this answers your question.

[SubzeroLT]

Makes sense. Thanks for sharing.


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[alons]

Just recalled posting this a while ago, which contains similar temp control along with some other goodies:

Next challenge..