2 3 4 VCC 2 A A 10K POT D1 D2 1 C1 R3 R4 3 R2 R1 P1 VCC 1 GND 2 3 U1 B 8 7 6 5 GND VCC OUT1 OUT2 1IN2IN- 1IN+ 2IN+ GND 1 2 3 4 B LM393 U2 1 2 C2 + Fire Sensor GND C C D D 1 2 3 4