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BillDumke1-Visitor
1-Visitor
August 5, 2011
Solved

Diode Circuit Lambert function

  • August 5, 2011
  • 2 replies
  • 6297 views

I was trying to determine the current flowing through a simple diode circuit, but I must have done something wrong. Neither the Lambert part of the current relation nor the current change any with VS and R. Anyone have any ideas?

BTW I used the soon to be extinct "Mathcad Collaboratory" to find Stuart's LambertW function. (I wish the Collaboratory would remain up as it is, even if we can't post anything. The files there do not exist in the Community.)

See attached Mathcad 11 file.

Bill

Best answer by RichardJ
I was trying to determine the current flowing through a simple diode circuit, but I must have done something wrong. Neither the Lambert part of the current relation nor the current change any with VS and R. Anyone have any ideas?

You overwrote the internal definition of "e".

I wish the Collaboratory would remain up as it is, even if we can't post anything. The files there do not exist in the Community.

I agree 100%. But I think they are going to wipe it out regardless of how much it upsets their users. I don't understand why, but they seem determined to do it.

2 replies

M
MikeArmstrong1-Visitor
1-Visitor
August 5, 2011

I know absolutely nothing about the functions you are using but the section below seems to be causing the problem. Should it be zero?

Clipboard01.jpg

This is making your Lambert function zero, thus making the equation none dependant on VS and R.

Mike

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BillDumke1-VisitorAuthor
1-Visitor
August 5, 2011

Thanks, Mike. I don't either. The LambertW function popped up when I did the symbolic solution for the current "I". Then I found Stuart's LambertW function and decided to try it.

Thanks for finding the location of the problem. Maybe I copied something wrong, or did something else stupid. I will check everything over in detail. I think it should work.

Bill

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RichardJ19-TanzaniteAnswer
19-Tanzanite
August 5, 2011
I was trying to determine the current flowing through a simple diode circuit, but I must have done something wrong. Neither the Lambert part of the current relation nor the current change any with VS and R. Anyone have any ideas?

You overwrote the internal definition of "e".

I wish the Collaboratory would remain up as it is, even if we can't post anything. The files there do not exist in the Community.

I agree 100%. But I think they are going to wipe it out regardless of how much it upsets their users. I don't understand why, but they seem determined to do it.

B
BillDumke1-VisitorAuthor
1-Visitor
August 5, 2011

Thanks, Richard. That fixed it!

(I was getting buried in the differences in the way Mathcad 11 and 15 were doing the symbolics, but I hadn't thought about that at all.)

On the Collaboratory, I guess we are supposed to reinvent the wheel a few hundred thousand times.

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