Optics: measuring and testing – Photometers – Photoelectric
Patent
1978-08-21
1980-08-19
Corbin, John K.
Optics: measuring and testing
Photometers
Photoelectric
324118, G01J 144, G01R 1918
Patent
active
042181402
ABSTRACT:
To permit a portable light meter to operate without zero adjustment and without excessive battery drain, a chopper-stabilized amplifier amplifies the DC signal from the light sensor of the light meter. The chopper in the chopper-stabilized amplifier is an FET circuit having a high impedance compensating circuit to avoid battery drain while compensating for interelectrode capacitance. The power supply obtains the ground level potential from the output of an operational amplifier with negative and positive potentials being generated from that reference potential so as to not require a center tap on the battery pack.
REFERENCES:
patent: 3704950 (1972-12-01), Rosencranz
patent: 3790288 (1974-02-01), Hostetter
patent: 4043676 (1977-08-01), Holzinger et al.
"A New Multi-Function Voltmeter for General LaboratorHewlett-Packar Journal, vol. 14, No. 9-10, May 1963, p. 3.
Biggs W. Walter
Johnston Jerome E.
Middendorf Lyle R.
Bovernick Rodney B.
Carney Vincent L.
Corbin John K.
Lambda Instruments Co.
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