How to convert the analog signal from the cooler revolution sensors to logical 0/1?

Question

Electronics

Logic 1/0 must be routed to the relay input to control the load.
Thanks in advance for any help.

Answer 1

Do you just need to track the fact that the cooler is working, or do you need to determine the speed?
There are circuits like this, https://www.electroschematics.com/3-wire-cooling-f...
if the frequency of the pulses from the cooler drops below the norm, the transistor turns on.
You can take a scarf like this https://aliexpress.ru/item/32973496530.html where a speaker is plugged into the connector, it beeps if the cooler has stopped, you can take the signal from this connector is running / stopped. At the same time, you can adjust the speed.