Figure 11(b), the diodes A1CR4 and A1CR5 are biased off. The resultant output
is a pulsating DC signal equivalent to the applied 10 kHz error signal. The
pulsating DC signal is filtered and applied to differential amplifier A1Q8 and
(3) The operation of the synchronous detector requires an in-phase
relationship between E3 and E4. The amplitude of E4 must be greater than that
of E3 at all times.
l. Feedback Differential Amplifier.
Pulsating DC from the synchronous
detector is filtered by A1C19, A1C20, and A1R35, amplified by A1Q8 and fed to
both the feedback current-squared generator A1Q11, and the feedback current
for A1Q10 and A1Q11 from excessive reverse bias when A1Q8 is not conducting.
m. Feedback Current Generator.
to the feedback current generator A1Q10.
A1Q10 serves two functions: 1) it
completes the metering loop to the metering bridge, and 2) it operates in
conjunction with the first 10 kHz amplifier, A1Q1,