| 摘要 |
An annunciation circuit is provided for an alarm signalling device, which annunciator causes a continuous indication of operation of the alarm signalling device after such operation. The indication is usually from a solid state light emitting device which is triggered from an SCR. The gate or driving circuit for the SCR is in series with a switch within the alarm signalling device, and is arranged to trigger the SCR only after the switch has operated. The SCR is in series with the solid state light emitting device and latches so that the light emitting device is maintained "on" until such time as power is temporarily removed from the circuit. A plurality of alarm signalling device may be powered from a single source and may operate a single alarm; and a simple visual inspection either of the annunciator board or of the devices themselves will show which device operated because the light or other annunciation will remain on until the SCR latch circuit is disconnected from its power source.
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