Fluke Biomedical 35035 - Manual (Page 7)

Theory of Operation
Introduction
2
2-1
Section 2
Theory Of Operation
2.1 Introduction
The purpose of this manual is to outline the operation and maintenance of the instrument. IT IS THE
RESPONSIBILITY OF THE USER TO DETERMINE THE SUITABILITY OF THIS PRODUCT FOR HIS
PARTICULAR MEASUREMENT CONDITIONS. The entire manual should be read before using the
meter.
Failure to observe all of the safety precautions
presented in Sections 1.2 and 1.3 of this manual as
well as those provided by the x-ray generator
manufacturer may result in serious injury.
The Inovision Model 35035 mA/mAs Meter has two functions: an mA function with three (3) ranges that
measures current in mA, and an mAs function with two (2) ranges that connects an integrator to read the
product of current and time in mA-seconds. Both range and function are selected using rotary switches.
Either DC or AC input mode is selected using a two-position rocker switch. The mAs function is reset by
means of a momentary push-button switch.
Operation of the meter requires a standard 9 V akaline battery. A low-battery warning appears in the
display when the battery is nearly depleted (7.2 V). Polarity is displayed as well. Blanking of display
digits indicates overrange.
A schematic of the input circuit of the Model 35035 is shown on the following page. R1, R2, and R3 are
current shunt resistors for range scaling and changing the input current flow into a voltage. F1, R15, D2,
and D3 are input protection devices that protect the shunt resistors and input circuit electronics from
excessive current and voltage. F1 is a 2 A, 250 V fuse that limits the input current. R15 is a 140 V
varistor that clamps high voltage pulses. D2 and D3 are 24 V zener diodes that clamp lower voltages.
WARNING