| 摘要 |
An alternative voltage source (1) delivers the power for stand-by state of an energy saving monitoring set-up (6). The superfluous power is stored in a storage element (2), i.e. a capacitor or accumulator. The voltage of the latter is monitored by a detector (3). If the voltage falls below a functional level, e.g. 3 v, an a.c.-d.c. converter (5) is switched on via an opto-coupler (4) until the storage element attains a voltage of approx. 5 v. The detector can switch a triac (4) which couples the converter to the mains. The max. current flowing through the converter is limited by a resistor. The voltage detector can control a second triac which switches on a power section. The detector can switch on a relay as well when necessary which also switches on a power section. USE/ADVANTAGE - Entertainment electronics, e.g. t.v., radio, v.t.r. stereo equipment, and industry, e.g. monitoring installation, intrusion or personnel detection, machines, battery charger, where stand-by mode is permanently switched on when not in actual operation. Present arrangement saves mains power since it is only called upon when actually needed to operate appts. Reduces risk of mains short-circuits and shocks.
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