Arthur L Davison

US Patent:

46201483, Oct 28, 1986

Filed:

Aug 27, 1984

Appl. No.:

6/644242

Inventors:

Arthur L. Davison - Canyon Country CA
Martin D. Blackburn - Costa Mesa CA
Donald A. Sellek - Manhattan Beach CA

Assignee:

Baird Corporation - Bedford MA

International Classification:

G01R 1706
G01R 1926
H03K 1302

US Classification:

324 99D

Abstract:

A precision current meter of wide dynamic range and sensitivity to low currents is disclosed. The precision current meter is particularly useful as a component for spectrochemical computations in spectrometers for the simultaneous multielement analysis of unknown samples in solution. The precision current meter comprises a source of input current, preferably a photomultiplier tube, an integrator having an integrating capacity for detecting the input current from the source, a source of reference currents including an offset current, a switch with a drain current coupled to the integrator. A clock is provided for generating clock signals for the current meter, including a series of pulses to actuate the switch and thereby to admit drain current segments to the integrator. A first counter is coupled to the output of the integrator to count the number of the series of actuating pulses during a predetermined time interval, and a second counter coupled to both the integrator output and the clock fixes the predetermined time interval. Preferably, both the integrator output and the switch are coupled via optical couplers to the counters.