This should be a simple question for someone who knows what he's doing. Unfortunately, I don't, so I've been researching like crazy and am stuck on where to go from here.
I am trying to modify a mini fridgerator for as cheap as possible to allow me to control the temperature from 55 to 90 degrees. I stumbled across several simple bimetal thermostat switches that have a pretty good range in them, but they are heating thermostats. I need to reverse these to cooling so that the fridge will activate at a certain warm temperature and turn off once it reaches set cooling.
Thus, when the thermostat is open, I need the fridge running. When the thermostat is closed, I need to fridge to stop running.
I think I've narrowed it down to either a SPST NC relay or a SPDT relay, but I'm stumbling heavily on the exact values I'm looking for. The normal fridge would accept 110 volt AC from the wall and output 110 volt AC into the unit. Normal operating amperage of these I beliefe is 3 – 5 amps, and most suggest the start up should provide 1.5 times that ammount. So my first question is, I guess I am looking for a 110v AC relay that can handle 5 – 7 AMPs?
If I'm on the right track, then my next concern is cost. I can find these in expensive electronics catalogs. I've looked on ebay, and they have some fairly simple and cost effective relays, but they are made for China outputting 240V capacity. Does this affect me, or because it's more than the 110 I should be ok?
Does anyone have better suggestions? Again, only looking to reverse this thermostat from heating to cooling. Shouldn't be this complicated! 🙂
Best Answer
Some thoughts:
Coupld of more points:
Anindo Ghosh recommends Omron SSRs from Ebay, something like this or this. Note that the output on these is 24-240VAC, so 110/120VAC is going to be perfectly fine. Anindo Ghosh says that he had units like this tested by Omron and they said they were genuine. And if you buy it and your house burns down, you can come and live with him :)