# LED shortage

Discussion in 'Homework Help' started by ShayanK1996, Feb 2, 2016.

1. ### ShayanK1996 Thread Starter New Member

Feb 2, 2016
2
0
Hi Guys!

I was hoping if any of you guys could explain to me on how you would know which LED goes bad when the voltage drops. (part c in the attachement)

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2. ### dl324 Distinguished Member

Mar 30, 2015
3,129
607
Welcome to AAC!

For homework, students are expected to show their work and Users will guide them to a solution.

Also post the values from the parameter file.

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3. ### ShayanK1996 Thread Starter New Member

Feb 2, 2016
2
0
VT = 0.25 V

Ig = 5 mA

Is1 = 30.72106 nA

Is2 = 10.30577 pA

Is3 = 562.6759 pA

Vgc = 7 V

I just need to understand the concept on how voltage is affects LED shortage.

4. ### dl324 Distinguished Member

Mar 30, 2015
3,129
607
Use the formula for calculating the forward voltage of each diode. Then add them together and see how that compares to Vgc.

What would the voltage across a shorted LED be?

Mar 24, 2008
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6. ### hp1729 Well-Known Member

Nov 23, 2015
1,849
207
Build it. I doesn't have to be LEDs. Resistors in series, same thing.