Pyroelectric Fire Alarm System Diagram.
The front end of the circuit contains a sensitive signal amplifier constructed close to IC1 (CA3130). It delivers a high output when temperature near the piezo component raises. IC CA3130 is really a CMOS operational amplifier with gate protected p-channel MOSFETs inside the inputs. It has high speed of operation and low input current specifications. There are certainly two inputs-the non-inverting input (pin 3) connected to the piezo component via diode D7 (OA71) that carries the voltage signal from the piezo component and the inverting input (pin 2) that gets a preset voltage through VR1.