This is a basic circuit for a Heat Sensor.
~Every Circuit doesn't have Sensors so has to use Potentiometer as Sensor.
~Top most Potentiometer is sensor which varies according to heat it receives from surroundings.
~Remaining 4 Potentiometers are presets for Op-Amp.
~DON'T change their values.
~They are used to define voltage level.
~Op-Amp here is configured as Comparator.
When Voltage on +ve is higher than voltage on -ve Op-Amp gives Output of 5V. Which drives the LED.
~Initially the sensor is at room temperature i.e. at 60% giving 2V which is lower than all preset levels.
~When you change the Sensor value to 50% First LED will turn ON.
~ Same way turn the Sensor upto 20% and all LED will light up one after other. Thus showing increasing temperature.
~I have run this circuit in Proteus and now planning to make it using Arduino which will replace all the Op-Amps.
~It is a small part of my college project which will work as temperature level indicator of the whole plant.
