amplification selector - scales from 0 to 999

scales from 0 to 999 An amplification selector is an ac- curate measuring instrument that is inserted into a signal path and then allows the gain of that signal to be set precisely between 0 and 999 in unit steps. Amplifier Al functions as a (unity 7-94 gain) buffer for the test signal which is subsequently applied to a chain of resistors, R8 . . . R16, and then to amplifier A4. Amplifiers Al . . . A3 are connected in cascade. Whereas Al has unity gain, amplifiers A2 and A3 have a gain of x10. Each of them is fol- lowed by a similar chain of resistors as Al, R17 . . . R25, and R26 . . . R34 respectively. From the chains, the signal is also applied to A4. The gain depends on the setting of switches S1 . . . S3. You will see from the circuit diagram that the resistor chains, together with R35, are part of the negative-feedback loop of A4. The result is a mixing amplifier with a conversion gain be- tween 0 and 999. The total resistance of each of the resistor chains is 100 k. If then...