"Davej" wrote in message
...
On Monday, February 11, 2019 at 4:26:47 PM UTC-6, Rod Speed wrote:
Davej wrote:
Rod Speed wrote:
Davej wrote:

Can anyone explain the internal circuit of a 3-pin
refrigerator thermostat such as a WDF-18 ? Thanks.

https://www.amazon.com/s/ref=nb_sb_n...tor+thermostat

One terminal is the common. That is connected to one
or other of the other two terminals depending on
whether the temperature is above or below the set point.

Oh, so what would a refrigerator need to apply
power to when it shuts off the compressor?

It doesnt, its just the way thermostats are usually done.

You see the same thing with oven thermostats too.

Its more obviously useful with room thermostats.

Hmmm, I've just removed one from a dorm-sized
fridge and there was a wire on every terminal.

Some thermostats do have an internal heater.
That reduces the hysteresis in the thermostat.
Bit counter intuitive why that approach works.

Now that you have it out, easy to use a multimeter
to see how that one uses the terminals.