| 摘要 |
A portion of the apparatus, which requires low voltage DC energy for its energization, is connected in series with an SCR between a single pair of input or energizing terminals. A series RC circuit is connected across the SCR, and the junction within this series circuit is connected through a zener diode to the gate of the SCR. When low voltage DC is applied between the input terminals, it turns on the SCR continuously and effectively appears across the noted apparatus portion to properly energize the latter. When high voltage AC is applied between the same input terminals, it turns on the SCR for only a predetermined part of each cycle of the AC. This part is made to be such that the resulting voltage across the noted apparatus portion is effectively the same when the high voltage AC is applied between the input terminals as it is when the low voltage DC is applied between the same input terminals.
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