| 摘要 |
<p>The alarm system comprises a compact unit fitted into a hole drilled into the housing of an automatic machine. The circuit includes a microswitch (1) connected across the twin-poles of the contacts (21) of a relay (7). Closure of the microswitch applies a 24 volt. D.C. power pulse to a signal lamp (20). In series with the power supply positive terminal (12) is a diode (11), and there is also a capacitor (17) connected in parallel. One of the relay contacts (9) is self-holding and the other (21) is a working contact. The housing of the machine is typically made of a non-conductive material, such as wood, and the alarm unit is sealed internally to the wall by an adhesive strip.</p> |
