SL134 Sensitive Temperature Control Lights Schematic

The thermostat is applicable within the range of -5 to 120 ° C, the circuit shown in the figure. AT is the the SL134 constant current source IC, it has three pin-out, use it on the need to control the temperature, by the three leads and the circuit is connected. SL134  characteristics as the ambient temperature changes in the output potential.
In the figure, the four parts of the AT, R1, and R4, R3, + the RP1 form a thermal bridge. With the SL134 placement of temperature change, the potential of point A will also change the potential signal is directly added to the 3 feet of the op amp A1 (5G23). AT the ambient temperature change of 1 ° C, point A potential change of about 10mV. The RP1 by adjusting the potentiometer, plus a voltage to 2 feet of the A1, A1 to form a differential amplifier form the differential signal from the amplification of the 6 foot output. A1, 6-pin output a negative potential (-0.3V) greater than +0.7 V when the output voltage of A1 is 6 feet, VT2 deadline, the VT3 conduction, and to promote the VT3 conduction, the red LED VL1 lit; The VT1 deadline, VT2 conduction, and to promote the the VT4 conduction, the green LED VL2 light.