Here is a simple freezer alarm circuit, but ultra sensitive with a buzzer. The circuit raises an audio alert when the temperature inside the freezer box goes up above a preset level. The circuit ...

The circuit has been designed to provide an alarm with the use of a buzzer when sensing high temperature by using a thermistor. Thermistor – one type of resistor used as temperature-sensing element ...

The first step is a thermistor, a conceptually simple device: resistance varies with temperature (seriously, how much more simple can a sensor get?). You can measure them by tapping the center of a ...