ne555 temperature regulation circuit diagram

Rt and R1 form a voltage dividing circuit. When the temperature increases, the resistance of Rt becomes smaller and the voltage at the dividing point increases. That is, the voltage of pin 5 of 555 increases, that is, the reverse voltage of pin 6 increases simultaneously (refer to 555 chip internal structure), the charging time of C2 from low level to high level increases, the time of outputting high level is extended, and the oscillation period also becomes longer; conversely, the situation is opposite. Thus, a square wave signal with variable high level time is output.