| 摘要 |
1,179,531. Photo-electric particle detecting apparatus. PYROTECTOR Inc. April 3, 1968 [April 2, 1967], No.16054/68. Heading G1A. In an arrangement for detecting the presence of particles in a light beam, the voltage drop across a resistive device in series with the light source is used to operate a second (lamp failure) alarm. Source 14 is energized through a voltage regulating arrangement comprising a transistor T1, Fig. 3, a resistor K1 and a Zener diode Z and the potential at the connection between the, emitter and the source 14 is used to switch a transistor T4 and thus control the lamp failure relay R2. The photocell C1 the supply to which is also regulated by the Zener diode operates relay R1 when particles are present. In an alternative arrangement for dialing with filament short circuit lamp failure a photocell responsive to the source light is connected between transistors T1 and T4. The particle investigation enclosure is the same as that described in Specification 918,908. |
