| 摘要 |
<p>A solenoid-operated device, for example a pneumatic valve, includes a solenoid coil (1), the normal operating voltage of which is about X volts, in combination with a modulating circuit (2) adapted to receive any constant control voltage input within a pre-determined range, for example 24 V to 240 V DC or AC. The modulating circuit (2) includes a pulse width modulator (6) which feeds to the coil (1), whilst the voltage input prevails either a constant voltage signal when the voltage input is equal or about equal to X volts, or pulsed voltage signals of amplitude equal to the input voltage and of such a pulse width/frequency that the time-averaged energy input into the coil (1) during pulsing is substantially equal to the energy input if a constant voltage signal of X volts were applied to the coil (1). Thus, one and the same coil (1), together with the modulating circuit (2), may be operated by any control voltage signal within a specified range thereby reducing the range of solenoids that, as presently, needs to be made and stocked. <IMAGE></p> |
