One of the thermostatic control circuits using 555 time base integrated circuit

An automatic controller is composed of a 555 time base integrated circuit and peripheral components. It does not
require a stable voltage power supply with good performance, because the voltage at each point is drawn from the same DC power supply, but the temperature control accuracy is very high.
    Thermistors with different resistance values ​​can be used as long as R is met at the required temperature. The relationship +RP= 2R4
is OK. When RP is large, a large adjustment range can be obtained, but the sensitivity will decrease. For Re, an MF12 negative temperature coefficient
sensitive resistor can be used.