基本信息
摘要：1,009,271. Semi-conductor circuit. ASSOCIATED FIRE ALARMS Ltd., and B.J.L. WHITE. March 2, 1964 [March 4, 1963], No. 8549/63, Heading H3T. [Also in Division G1] The voltage at a point 17 between an ionization gauge 10 responsive to the amount of smoke in the atmosphere, and a resistor 11, which may be a second ionization chamber closed to the atmosphere, is applied to the modulator of a field effect transistor 14 fed from an LT source 16, and when as a result of smoke the voltage drops below that at point 18 current through transistor 14 ceases and point 20 which is set to become positive with respect to point 19 eventually renders transistors TR1 and TR2 conductive, diode D3 making the arrangement bi-stable. The larger current drawn from the source by the transistors actuates a relay in the supply lead. Capacitor C ensures that transistor TR1 does not conduct immediately on reset. A number of such circuits may be connected to a single LT power source, and the relay may be responsive to the total current drawn. Transistor 14 may be coupled to point 17 by a capacitor to make the circuit responsive only to rapid changes. Component values are exemplified.
摘要附图：
