Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1988-02-05
1989-08-01
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
250214AG, H01J 4014
Patent
active
048535290
ABSTRACT:
The image intensifier (22) of night telescope (12) is protected by a deactivate circuit (FIG. 4) which is in series with an off-on switch (S) between a source of electrical energy (28) and the image intensifier (22). The light sensor (26) measures ambient light. If the light level is below a predetermined light level, at which it is safe to operate the image intensifier (22), the light sensor (26) does not conduct. This causes an amplifier circuit (A-1, A-2) to deliver a negative voltage to the base of a transistor (Q-1). This enables the transistor (Q-1) to transmit electrical current from the source (28) to the image intensifier (22). Whenever ambient light exceeds the predetermined light level, the photoconductive sensor (26) conducts. In response to this happening the amplifier circuit (A-1, A-2) delivers a positive voltage to the base of the transistor (Q-1). In response, the transistor (Q-1) becomes incapable of transmitting a current onto the image intensifier (22).
REFERENCES:
patent: 3739178 (1973-06-01), Chow
patent: 3816744 (1974-06-01), Chow
patent: 4707595 (1987-11-01), Meyers
patent: 4755725 (1988-07-01), Kastendieck et al.
Allen Stephone B.
Nelms David C.
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