Hi
I want to build a small circuit which will alert me once the temperature in my fridge goes up. (its an old fridge and it stops working once in 2 or 3 months).
I thought to use a thermistor that will be in the fridge. as shown in the image attached.
I think it should work,but as i'm a beginner in electronics, I thought it would be wiser to be sure before I buy the components.
The main idea of my circuit is that V- of the comparator(LM311N) gets constant 3.33v (5v divided by 50Kohm and 100Kohm).
When the temperature is right, the thermistor value is 100Kohm and V+ of the comparator gets 2.5V = lower than 3.33V. then the output is VS- which is 0.
When the temperature rises above the alert temperature, the value of the thermistor is above 50Kohm and V+ of the comparator is above 3.33V. then the output is VS+ which is 5V.
This 5V triggers the relay. and the relay activate the alarm, which will include a buzzer and a led.
will it work?
and for another thing - once the temperature will rise, there will be a few minutes that the 2 inputs will be balanced. The output will probably flip from 5V to 0 all this time. will it be wise to connect a capacitor with a resistor in the output in a way that only if the output will give 5V for 2-3 seconds,it will trigger the relay?
thank you for any answer