JPH02113074U - - Google Patents

Description

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an embodiment of this invention, Figure 2 is a circuit diagram showing an embodiment of this invention.
The figure is a circuit diagram showing a conventional example, Figures 3a and b show the operation of the conventional example, a is a signal current characteristic diagram, b is a heat loss characteristic diagram, and Figure 4 a and b are other examples of the conventional example. The operation is shown in which a is a signal current characteristic diagram and b is a heat loss characteristic diagram. Explanation of symbols of main parts, 4...Solenoid, 5
...Power transistor, 6...Photocoupler,
17...Capacitor (surge voltage detection circuit), 2
0...Transistor (short circuit).

Claims (1)

[Claims for Utility Model Registration] 1. A semiconductor switching element connected in series with a solenoid between a pair of power terminals, and controlling conduction/cutoff to the signal input side of the semiconductor switching element in response to a step-shaped switching command signal. a surge voltage detection circuit connected to a connection point between the solenoid and the semiconductor switching element to detect a surge voltage generated when the solenoid is deenergized;
An electromagnetic valve drive device comprising: a short circuit connected between a signal input side of the semiconductor switching element and ground, the short circuit being made conductive by a surge voltage detected by the surge voltage detection circuit. 2. The electromagnetic valve drive device according to claim 1, further comprising a capacitor as the surge voltage detection circuit. 3. The electromagnetic valve drive device according to claim 1 or 2, wherein the short circuit is constituted by another switching semiconductor element.