Question

In the following circuit, $RC$ is much larger than the input period. Assume diode is ideal and $R$ is large. The dc output voltage across $R$ will be .............. V. (Specify answer up to one digit after the decimal point.) 

Hint:

When $RC \gg T$, output of rectifier ≈ peak of input signal.

Answer 1

Correct Answer: 66

Step 1: Note that $RC \gg T$.
Thus capacitor charges to peak voltage and discharges very slowly — typical peak detector.

Step 2: Input is 24 Vrms.
Peak voltage = $24\sqrt{2} = 33.94\ \text{V}$.

Step 3: Ideal diode.
No drop across diode, so capacitor charges to full peak voltage.

Step 4: DC output across $R$.
Since discharge is negligible, $V_{out} \approx V_{peak} = 33.94 \approx 34.0\ \text{V}$.