Need Help to Control Refrigerator Temp

[sarafina]

I have an old refrigerator in my garage that unfortunately is working perfectly . I would like to use it to age cheese and my husband wants to use it for his beer making so we need to control the temp from 50-55 Deg F. Right now I have it on a simple mechanical timer to shut it off for extended periods which is working ok for now, but I need temperature control so I don't have to keep changing the timer as the weather warms up.

I can buy a controller for $80 that has a sensor you stick in the fridge and plug your refrigerator into and it kicks the power off and on to maintain the temp with some hysteresis so it doesn't cycle too much but I was hoping I could build my own a lot cheaper. I can do simple wiring but not build circuit boards so I need components that I can buy and put together.

I have looked on the net until my head hurts and haven't been able to find all the right pieces. I can't use a regular thermostat because 50-55 is the low end of the range and probably wouldn't work very good.

Any suggestions?

Thanks!
Sarah

 

[vne147]

Sarah,

You can build a circuit much cheaper than $80. You can use a thermistor, a comparator, a bunch of resistors and a few pots to create a temperature dependent control signal. You can then use that signal to turn your refrigerator on and off. That part can be accomplished several ways and I'm not sure which way is best. Maybe someone else can advise you on that. I've been working on a similar project and have a current thread about it called Thermistor and Comparator Circuit. I actually just did some testing of the circuit the results of which I'll post shortly. I can keep the test setup put together for the time being so I can test your setup when you get that far.

 

[tcmtech]

Here you go! Selco - WKF20.6E-007-020 - Allied Electronics -31 F to +104 F adjustable thermostat for under $15!

If you can connect two wires and turn a knob your probably qualified to install it too!

Some times you just have to know where to look first instead of last!

 

[vne147]

Here you go! Selco - WKF20.6E-007-020 - Allied Electronics -31 F to +104 F adjustable thermostat for under $15!

If you can connect two wires and turn a knob your probably qualified to install it too!

Some times you just have to know where to look first instead of last!

Definitely more simple than my idea.

 

[sarafina]

Here you go! Selco - WKF20.6E-007-020 - Allied Electronics -31 F to +104 F adjustable thermostat for under $15!

If you can connect two wires and turn a knob your probably qualified to install it too!

Some times you just have to know where to look first instead of last!

Thank-you - that is EXACTLY what I am looking for!!!

You guys are GOOD!