Incubator Electronic scheme

ATTENTION! After power supply connect the scheme components are under high tension! Take all necessary precautions! All the resistors are 0,125 watt. Nominal values are given in the scheme. Save the picture on your computer to see it with better quality.After that the board of the temperature regulator should be made.

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Description of operation/Operation description

Datum nodes of the thermoregulator: comparison circuit (U2), power commutation circuit (U1, Q1) and power source (D2).

The comparator circuit is assembled on the only U2 comparator and performs the comparison of signal levels on the resistive dividers R5,R8 and R6,RT1.

As a measuring thermoelement the RT1 thermoresistor is used.

Its value can be from 1 to 11 kiloohm.

Depending on the value of the thermoresistor resistance you should select the R6 resistor.

The level of the response of the comparator is set by the R8 variable resistor. The R7 resistor sets the value of the circuit hysteresis and, when necessary, the resistor of another nominal can be chosen.

The specificity of the force diagram is that the symistor control is performed by means of the U1 optosymistor that contains the circuit of comparison of the mains voltage changeover through 0.

The usage of this element allowed, on the one hand, to realize the galvanic separation of the control circuit, and on the other hand, to decrease the interference created by this device.

The power source needs no comments.

For the purpose of cooling the power symistor it is recommended to apply the radiator with the area of approximately 30 square centimeters with the load of 500 watt.