# Equivalent V-A Characteristics Of Two Diodes?

Discussion in 'Homework Help' started by kurvi4ka, Jun 22, 2013.

1. ### kurvi4ka Thread Starter New Member

Jun 22, 2013
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Hi, everyone. Can someone please help me with this problem? How to draw the equivalent V-A characteristics of two diodes? Thanks, in advance!
Examples:

2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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For sure we can help. But it will be better if you show as your attempt to solve this problem.

3. ### kurvi4ka Thread Starter New Member

Jun 22, 2013
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OK. This is what will happen from my deductions. Sorry I don't know how to use software to do graphics, and sorry that I don't have a scanner

PS Sorry again for the inconvenience.

4. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Your V-A characteristics looks good. But why you reverse the voltage polarity in the second pic? Why not 15.3V on first quadrants and 1.4V on the third quadrants ?

5. ### kurvi4ka Thread Starter New Member

Jun 22, 2013
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Ooops. Yeah, you are right, my bad. Thanks for the posts.

6. ### screen1988 Member

Mar 7, 2013
310
3
Hi, I don't understand what the problem supposed to do.
Can anyone explain?
How the two first circuits and final circuit are possible?

7. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Can you explain your question bit more? Because I don't understand you question.

8. ### screen1988 Member

Mar 7, 2013
310
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Jony,
For example, in the second circuit, there are two zener diodes in series. One with 6.3V and the other is 9V. Why this circuit possible? I think there is a short circuit here.
I don't understand these circuits.

9. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Well I don't see any "short" here. The task was to draw V-I characteristics on the plot.
Why you see a short? If you need to plot V-I for a single si diode you will also see a short?

10. ### screen1988 Member

Mar 7, 2013
310
3
I don't understand the circuit:

Why 6.3 V can be in parallel with 9V? Is this a short circuit?

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11. ### Jony130 AAC Fanatic!

Feb 17, 2009
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This circuit act just like two diode connected in parallel.

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12. ### WBahn Moderator

Mar 31, 2012
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These aren't batteries and the diodes aren't generating 6.3V and 9V. w

A normal silicon diode has about 0.7V across it when it is forward biased and conducting current, right?

A germanium diode has about 0.3V, right?

Let's say that you had a circuit that had both kinds of diode in it. You could write "Si" and "Ge" next to them (or a part number) to let you know which is which. But you could also write "0.7V" and "0.3V" next to them, right?

It's the same thing here. The "6.3V" and "9V" are simply labels telling you what the reverse biased voltage is when it is conducting in that direction.

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