# clipper circuits problem

Discussion in 'General Electronics Chat' started by bubbleliiciouz, Jul 28, 2008.

1. ### bubbleliiciouz Thread Starter New Member

Jul 28, 2008
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help! i cant understand simple parallel clippers,,

plz help me.. i dont know how to graph and to get the Vo, etc..

i cant really understand the topic..

Apr 5, 2008
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4. ### SgtWookie Expert

Jul 17, 2007
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I think you nailed it, Bill.

Bubbleliiciouz, that's definitely a difficult concept to wrap one's head around in the beginning. It might help you to step back and re-visit diodes.

It's generally accepted that a typical silicon diode has a forward voltage drop (Vf) across it when it's conducting. You'll see a variety of Vf values thrown around on here, but the truth is that Vf's vary depending upon the basic type of diode and the current flowing through it.

Have a look at the attached chart. The other day, I selected a random 1N4148 diode and subjected it to various currents, and charted the results. Now, not every 1N4148 will have exactly that response, but it will be reasonably similar. Notice that the response is very linear up to around 20mA, after which the Vf heads for the stratosphere. I stopped the test at 100mA, as the diode would have failed not long after that; 100mA is the maximum rating for that particular diode.

So, that explains why the "clipped" waveforms are so rounded-off looking. The diode actually begins conducting at rather insignificant current levels.

As far as the parallel clippers go - one diode conducts when the polarity across the pair of diodes is one way, and the other diode conducts when the polarity across the pair of diodes is inverted.

If you're still confused, feel free to post again. We'll try to help you over this hurdle.

Everyone hits "walls" when they're learning new things. You're not alone.

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