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10.3 General Circuit Descriptions
The ohmmeter may be divided into four separate parts.
4176 Main Board (4176-700)
– This portion of the ohmmeter contains the power supply
and the constant current source.
Power Supply – This section converts the AC line power into the DC levels
necessary to power the ohmmeter’s circuitry.
Constant Current Source - This section of the main board provides a stable test
current that is passed through the load to develop a voltage across it. The value of
this current for each range is indicated on the front panel of the instrument.
Micro-Controller Board (834u-700)
–This is the central processing unit of the
ohmmeter. The analog to digital conversion, the range selection, LED indicator selection
and all other decision making processes occur in this portion of the instrument.
ADC – The micro-controller’s analog to digital converters sense the voltage drop
across the load.
TCM ADC - The micro-controller’s analog to digital converter sense the voltage
across the temperature sensor (Omni Compensator).
