Fluke 8842a instruction manual Detailed Circuit Description, DC Scaling

8842A

Instruction Manual

5-3. DETAILED CIRCUIT DESCRIPTION

The following paragraphs give a detailed circuit description of each of the functional blocks in Figure 5-1. For clarity, measurement ranges are referred to as r1, r2, r3, etc., where r1 is the lowest possible range, r2 the next higher range, and so on. Pins are designated by the respective integrated circuit (e.g., U101-7 for U101 pin 7).

5-4. DC SCALING

The DC Scaling circuit scales all in-range dc inputs so that the output of the Track/Hold (T/H) amplifier (U307) is within +/-2V. In addition, the DC Scaling circuit provides input protection and analog filtering. Additional scaling is provided by the the T/H Amplifier.

The following paragraphs describe the configuration of the DC Scaling circuit in the DCV and mA DC functions and also describe the analog filter. The ohms functions are described under a later heading because the T/H Amplifier provides additional input switching for these functions.

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