Joined Dec 29, 2010
i wan make this circuit as temperature sensor.......... whenever i heat up the thermistor, the resistance of the thermistor will drop and then make the circuit work......
In order to make your circuit work without redesigning, you have to add in some components like others have said. The modified circuit is as attached.

The thermistor is 10K when cool, adjust RV1 to about 80-90% where the LEDs are not lighted. Then heat up the thermistor with a hair dryer. When the resistance of thermistor is lower than that of the RV1. The output of comparator will be high and the transistor Q7 will conduct and allow current to flow into the FF circuit. :D