| 摘要 |
<p>A flame detector for a fire fighting system has a photo cathodic tube sensitive to ultra-violet radiation. This is supplied by a direct-current to alternating-current converter connected to a circuit with a capacitor and a resistance integrating the tube supply circuit. The supply voltage is regulated by a set of transistors a zener diode and a divider potentiometer. The current variations emerging from the detector cathode are processed, in pulse form, by a set of two comparators. One of these acts as an integrator and the other as a resetting device to zero every 30 seconds for which the impulses are counted. An alarm is initiated if this number exceeds six.</p> |
