| 摘要 |
PURPOSE:To obtain a voltage detection type switch circuit which has the stable actuation in a multi-current output mode and also can be set in a small space, by controlling the current flowing through a constant voltage power supply circuit part. CONSTITUTION:The light receiving side of a photocoupler 34 of a constant voltage power supply circuit part 22 is turned on with an output kept on an ON state and by the feedback carried out at the light emitting side of the photocoupler 34. Thus a thyristor 35 is set at a high impedance and therefore the current flowing to a Zener diode ZD36 is limited by a resistance 26 of a high resistance level. When the output is turned off, the width of the detection voltage can be set at a large value by a resistance 25 of a low level. Furthermore the heating of the ZD36 is prevented even through the voltage of a high level is applied to an area between (b) and (b') after the output is once turned on since the current flowing to the ZD36 is reduced. Thus a stable current is supplied to the output.
|
