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ptc-48653081-Visitor
1-Visitor
April 17, 2013
Question

Help calculating range of output, with component tolerances

  • April 17, 2013
  • 5 replies
  • 4431 views

Hi.

I am new to using MathCad, so I hope I am not asking too simple of a question.

I have to calculate a voltage range on my input pin, depending on component tolerances and voltage tolerance. lets say I have a voltage which ranges from 6 to 18V,nominally at 12 and a simple voltage divider with R1/R2, each with 5% resistors, which functionality of Mathcad would give me a nice output of voltage ranges on my output ( that is between R1/R2).

the circuit is naturally more complex, I am just trying to lean how to and then expand once I know.

with this simple circuit, I would just put in min and max values and only have a couple of individual calculations, but my actual circuit has a lot more components, and calculating the range of outputs, with tolerances becomes a large task, if there is no function to give me the range

I btw, am using MathCad Prime 1.0

thanks very much in advance.

Kasper

5 replies

Werner_E
Werner_E25-Diamond I
25-Diamond I
April 17, 2013

In no way a simple question (unfortunately).

You will have to write a routine to do the task.

Each variable with tolerance be represented by a vector (of "enough" values, as for more complicated functions it would not suffice to just use min amd max value) and the routine would cycle through all possible combinations, collecting and returning the results in a vector. Not easy to make that a general, all purpose routine, I guess.

You may look if this thread is of any help http://communities.ptc.com/message/199660#199660

The files are in Prime2 format and I don't know, if Prime1 would be able to read them. I also don't know of a way to convert from Prime2 to Prime1. If you can't read it, I could provide a pdf so you can at least have a look at it.

There is another, older thread which might be of interest, http://communities.ptc.com/message/33843#33843, the files are in an older Mathcad format, which could be converted in Prime format, if necessary.

ptc-48653081-VisitorAuthor
1-Visitor
April 17, 2013

Thank you , Werner.

I was hoping there was a function build in, but since there is not, I suppose I may venture into making a routine. the samples are indeed in prime 2.0 format, and prime 1, cannot open them.I tried. a .pdf would be greatly appreciated of especially the minmax function.

thanks

Kasper

Werner_E
Werner_E25-Diamond I
25-Diamond I
April 17, 2013

Attached find the three files mentioned in the threads, hope it helps.

You know that you can download Prime2 which, after a 30 day trial period will regress to Prime Express, a versions can be used for simpler tasks, but things like symbolics or solve blocks are considered premium functions and are locked. That was the reason for me to provide the minmax sheet in the above mentioned thread, which does not make use of solve blocks and obviously worked for the questioner in his Express edition of Prime. The routine provided there tried to be a more general solution and should work with more complex functions/circuits, too, I hope.

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