| 摘要 |
PURPOSE:To prevent an erroneous operation of a control circuit by a construction wherein a regulator circuit regulating the electrification of an exciting coil by a semiconductor element in response to a small power is provided in a power transmission line for supplying a power supplied from a contact of a temperature control mechanism to a control terminal of the semiconductor element. CONSTITUTION:When an output of 24V is present at a terminal No.1 of a connector 120 (in a heating operation), the voltage of 24V is divided by resistors 128 and 129 and an output obtained thereby is supplied to a buffer 108 through a Zener diode 130 and impressed on an auxiliary relay 107 for switching a fourway valve. By using the Zener diode 130 in this way, passing of a Zener voltage or a voltage lower than this is checked and a leakage power caused by noise or an electric heater is interrupted. When an output is present at a terminal No.3 of the connector 120 (in an operation of a compressor), the output obtained by the similar voltage division by resistors 133 and 134 is supplied to a comparator through a Zener diode 135 switching transistors 136 and 137 and a resistor 138, so as to electrify an auxiliary relay 106 for operating the compressor.
|
