Need suggestion for thermostat circuit

[BuzzTronic]

HI ALL,

I have an air conditioner with removed electronics. I can manually control the compressor and blower easily enough, but there is a little freeze sensor that changes resistance as the temperature changes. I need to use that to interrupt the compressor relay.

I'm thinking there must be a way to use a simple transistor based circuit so when resistance reaches a threshold, it stops the relay trigger power. Pretty simple but I dont know enough to design something, so looking for some suggestions.

Thank You!

 

[kellys_eye]

I have purchased and used a simple digital readout thermocouple controlled switch like this:

https://www.ebay.co.uk/itm/High-pre...hash=item239b91d3a9:m:mPkQPvgXXvQF0StGvtUrNdQ

it works from -50 to +110C, can switch at rising or falling temperatures, has adjustable hysteresis etc and for the price you can't do better. It even comes with it's own thermocouple.....

 

[BuzzTronic]

thanks, but I am looking to learn how to make this as simple as possible with few components...

suggestions?

 

[kellys_eye]

Ok, simple circuits are a-plenty via Google:

https://www.google.com/search?q=the...ktPHaAhUUWsAKHQqiA-8QsAQIKA&biw=1855&bih=1079

but the module I suggest is basically 'one component' and if you can build one from 'a few components' cheaper than that module costs then please go ahead. I'd like to see your results too!