摘要 |
An audio signal device for a door mounted advertising display, the device includes a signal unit, a battery connected to said signal unit, the unit including a tone generator, a pulse generator connected to control the tone generator, a timer connected to control the time of operation of the pulse generator, and a motion switch connected to energize the timer in response to the motion of the door, the timer further including a circuit for preventing reactivation of the timer for a predetermined period of time.
|