
Principles of Analog Electronics
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phenomena mentioned before. If the frequency of bulb lighting corresponds to
that of house voltage (60 Hz in the United States, 50 Hz in Europe) the bulb will
always be lit (given the phenomenon of image persistence on our eye’s retina that
we have already discussed in the “Curiosities” note in Section 1.2 of Chapter 1).
Let us examine this phenomenon in detail (Figure 4.56):
➜ During the rst quarter, period (1) in the gure, a charge interval, voltage
increases positively from zero to a maximum value V
CM
. The capacitor must
accordingly be charged by a positive current, which starts from its maxi-
mum value ...