KTY10 LM2903 TEMPERATURE SENSOR RELAY CONTROL Schematic Circuit Diagram

The circuit of the circuit you see in the diagram is made from the ends X3-1 and X3-2. The voltage from 11-15V entered from this input is provided by the materials D6, c8 and C9 for a half-wave rectifier supply for the circuit. KTY10 has two temperature sensors on the circuit . These two sensors are connected to the terminals TH1, X1-1 and X1-2, and TH2 to the terminals X2-1 and X2-2. The supply of these two temperature sensors is ensured via R1, C1, C2 and R2, C3, C4 resistor and capacitors. The temperature that falls on the TH1 and TH2 sensors changes the internal resistance of these sensors and passes over the values ​​P1 C1, R5 and enters the low-power dual-voltage comparator.

LM2903I01A and I01B have two low-power comparators. R3 is linked to the inverse input of the comparator C6 I01A, R4, R6, C7 is the non-inverse input of the comparator I01B. The resistance of R7 depends on the inverting output of the I01A comparator and the R8 resistance on the non-inverse outputs of the comparator I01B. The P2 potentiometer controls these two groups of comparators. In case the comparator outputs are negative, D3 and D4 diodes are not passed and D1 is over R9 and D2 goes over to R10. In the meantime, the R12 resistance is connected to the ground at the base end of the T1 darligton transistor and the transistor is not in the transistor transmission. When the outputs receive a positive position, the LEDs D1 and D2 are off, the current passes through the D3 and D4 diodes, and the T1 voltage transistor is transmitted via R11.

Caution: LM2903 Op amp feed legs on the diagram are not shown, leg 8 is no + plus 4 is the leg – minus in the diagram out of the places where vcc feed connection on these legs