Interfacing PIC Microcontrollers

Therefore, in this circuit, we will calibrate the amplifier by adjusting the

offset to approximately the correct value at the mid-output level (1.280 V),

and then adjusting the gain to give the right output at the maximum level

(2.500). These steps are then repeated until the reading is correct at the mid

and max values. This is usually necessary because the gain and offset inter-

act, that is, adjusting one affects the other. In practice, multi-turn pre-set pots

(typically 10 turns) are often used to give greater sensitivity or range to the

adjustment.

In this circuit, a relatively small offset voltage is required, and it is obtained

by taking the forward ...