Solutions to and Comments on the Laboratory Exercises

Many commercial oscillators have an output resistance of a few hundred ohms. If distortion of the signal V_i applied to the input of the circuit shown in figure 17.2 is to be avoided when R is small, the reactance 1/ωC must be much larger than this output resistance. In fact, unless ωC is small enough, the output resistance of the oscillator in conjunction with the capacitance C tends to integrate in front of the C—R circuit being investigated. Hence C and ω should not be increased above the values suggested to get τ ≫ T. As instructed, this must be achieved by making R large.