GB915380A - Improvements relating to photo-sensitive circuits employing transistors - Google Patents

Improvements relating to photo-sensitive circuits employing transistors

Info

Publication number
GB915380A
GB915380A GB4377160A GB4377160A GB915380A GB 915380 A GB915380 A GB 915380A GB 4377160 A GB4377160 A GB 4377160A GB 4377160 A GB4377160 A GB 4377160A GB 915380 A GB915380 A GB 915380A
Authority
GB
United Kingdom
Prior art keywords
photo
circuit
transistor
sensitive
conducting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB4377160A
Inventor
Geoffrey Thornton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Associated Electrical Industries Ltd
Original Assignee
Associated Electrical Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Associated Electrical Industries Ltd filed Critical Associated Electrical Industries Ltd
Priority to GB4377160A priority Critical patent/GB915380A/en
Publication of GB915380A publication Critical patent/GB915380A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Electronic Switches (AREA)

Abstract

915,380. Photo transistor relay circuits. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Oct. 31, 1961 [Dec. 20, 1960], No. 43771/60. Class 40 (6). A photo-sensitive indicator comprising a pair of transistors T1, T2 coupled to form a twostate circuit, and a photo-sensitive element connected so that the conductive state of the circuit depends on the illumination reaching the element is characterized in that means are provided for preventing the return of the circuit to one of its two states for a predetermined minimum time irrespective of any intervening change in illumination of the photo-sensitive element. As shown in Fig. 1, the load R2 has a larger resistance than the relay coil 1 so that when the circuit switches from T2 conducting to T1 conducting the the current through R4 decreases, and the potential at point A goes more positive. This positive change is fed through capacitor C1 to reverse bias the base of photo-transistor P1 until the capacitor charge takes up its new value. During this time P1 remains non-conducting irrespective of any increase in illumination. In an alternative embodiment, Fig. 2, the photo-sensitive device is a diode P2 and the capaciter C1 is connected to apply bias to the base of a transistor T3 arranged to be switched by the change in conduction of the photo-diode. The circuit operates in an identical manner except that it is the transistor T3 which is controlled by the potential at point A and not the photo-sensitive device. Specification 874,915 is referred to.
GB4377160A 1960-12-20 1960-12-20 Improvements relating to photo-sensitive circuits employing transistors Expired GB915380A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB4377160A GB915380A (en) 1960-12-20 1960-12-20 Improvements relating to photo-sensitive circuits employing transistors

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4377160A GB915380A (en) 1960-12-20 1960-12-20 Improvements relating to photo-sensitive circuits employing transistors

Publications (1)

Publication Number Publication Date
GB915380A true GB915380A (en) 1963-01-09

Family

ID=10430246

Family Applications (1)

Application Number Title Priority Date Filing Date
GB4377160A Expired GB915380A (en) 1960-12-20 1960-12-20 Improvements relating to photo-sensitive circuits employing transistors

Country Status (1)

Country Link
GB (1) GB915380A (en)

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