Capacitor-input filter

<h2 id="operation">Operation</h2>
<p>While during the time the rectifier is conducting and the potential is higher than the charge across the capacitor, the capacitor will store energy from the transformer; when the output of the rectifier falls below the charge on the capacitor, the capacitor will discharge energy into the circuit. Since the rectifier conducts current only in the forward direction, any energy discharged by the capacitor will flow into the load. This results in output of a DC voltage upon which is superimposed a waveform referred to as a sawtooth wave. The sawtooth wave is a convenient linear approximation to the actual waveform, which is exponential for both charge and discharge. The crests of the sawtooth waves will be more rounded when the DC resistance of the transformer secondary is higher.
</p>
<h2 id="ripple-current">Ripple current</h2>
<p>A ripple current which is 90 degrees out of phase with the ripple voltage also passes through the capacitor.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Rectifier/me8XDxND">Rectifier#Capacitor input filter</a></li>
<li><a href="/facts/Choke-input_filter/me8XDxND">Choke-input filter</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Slurzberg; Osterheld (1948). Essentials of Radio. McGraw-Hill. p. 510. <a href="https://archive.org/details/essentialsofradi00slur" target="_blank">https://archive.org/details/essentialsofradi00slur</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Capacitor-input filter open-in-new

Capacitor-input filter