| 摘要 |
PURPOSE:To improve the reliability of soldering by constituting a soldering iron in such a manner that the current of the solenoid of a vacuum pump rises from zero when a switch on the iron side is turned on. CONSTITUTION:The control terminal side of a solenoid control circuit 1 of the vacuum pump is connected to an AC100V power source 6 via a DC constant voltage circuit 3 and the connecting switch 20 of the iron part 2. A varister 7 is connected in parallel to the outside side of the control circuit 1. DC 12V is supplied to the circuit 1 and the current from the power source 6 is conducted to the solenoid 9 when the switch 20 is turned on. The timing in this state is the timing delayed until the zero cross part detects the point of the time when the power source 6 attains 0V. The generation of the counter electromotive force to the solenoid 9 is thus prevented and the breakdown of the electric parts is obviated.
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