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18.10 Filters
The outputs from detector circuits b and c in Fig. 18.8 are something
like the dashed line in Fig. 18.7. Both types of output contain the
desired modulation signal, and both contain also a unidirectional
What about the reservoir or peak detector, Fig. 18.86? This looks
difficult to assess because, as Fig. 18.7 shows, the tuned circuit is
unloaded during most of each cycle, but for an unspecified period at
each positive peak it is connected by the diode to R and C in parallel.
But if we assume that the nearly steady voltage across C is equal to
the peak input voltage (in practice, with suitable component values,
it nearly is) ...