The Museum of HP Calculators

HP Forum Archive 20

 Re: The lost formulaMessage #1 Posted by John B. Smitherman on 17 Jan 2011, 8:19 a.m. We don't know what we don't know. Regards, John

 Re: The lost formulaMessage #2 Posted by Martin Pinckney on 17 Jan 2011, 8:57 a.m.,in response to message #1 by John B. Smitherman If anyone understands the meaning of this thread, I would like to know.

 Re: The lost formulaMessage #3 Posted by Norman Dziedzic on 17 Jan 2011, 11:17 a.m.,in response to message #2 by Martin Pinckney Seems to me like just a question of curve fitting. A thermistor is an electronic device whose resistance changes with temperature in a predictable, albeit nonlinear, way. See:http://www.vishay.com/doc?29053 I'm guessing the OP used to have a simple equation to approximate a particular thermistor response at one time and lost it.

 Re: The lost formulaMessage #4 Posted by Martin Pinckney on 17 Jan 2011, 1:21 p.m.,in response to message #3 by Norman Dziedzic Thanks for responding, Norman. Quote: A thermistor is an electronic device whose resistance changes with temperature in a predictable, albeit nonlinear, way. I'm guessing the OP used to have a simple equation to approximate a particular thermistor response at one time and lost it. That much I got. Quote: On reading something everyone impress it on the matrix of "what they know". There can be nothing new under the sun, everything that can be learned has always been learned. You miss a lot of information that way. The impact of what I wrote is that there is a simple accurate method not disclosed by usual methods. Read the message with an open mind, your brains won't fall out. Sam _______________________________________________ things which have been (very) tedious in the past may be far easier nowadays and become even easier in the future, caused by new insight or just compilations of older insights. This process goes on and on... Walter _______________________________________________ We don't know what we don't know. John The rest not so much.

 Re: The lost formula - lost in translationMessage #5 Posted by Norman Dziedzic on 17 Jan 2011, 3:05 p.m.,in response to message #4 by Martin Pinckney I think I had my high pass filter on and didn't absorb that part of the thread ;-/

 Re: The lost formulaMessage #6 Posted by Walter B on 17 Jan 2011, 4:49 p.m.,in response to message #4 by Martin Pinckney Martin, let me explain. As far as I understood the OP, he had found a simple method decades ago describing the electrical behaviour of a thermistor had used something like experimental math (or call it trial and error) for his finding since he had known no other way then can't find it again but doesn't want this knowledge getting lost keeps pointing us to this therefore. I admit I don't know for sure what the OP wants us doing. So my answer could have been like John's, but I didn't want to leave an old man out in the rain. Thus I thought a bit and guess: If that behaviour is of practical relevance, it was solved in the time between - or it can be modeled easily by some brute force fitting algorithm using the tools available today, which where beyond imagination decades ago. So the OP's problem is most probably solved now either way by the advancement of science ... dona eo pacem! HTH. I'm most willing, however, to delete my two postings in this thread if they will cause any trouble whatsoever ...

 Re: The lost formulaMessage #7 Posted by Martin Pinckney on 17 Jan 2011, 6:04 p.m.,in response to message #6 by Walter B Walter, I think I've got it now. Thanks for your help. No need to delete anything.

 Re: The lost formulaMessage #8 Posted by designnut on 18 Jan 2011, 1:27 a.m.,in response to message #7 by Martin Pinckney I think I probably started adding 273 to the C temperature and found that was not quite the right slope and adjusted from there. I'll give it a try through programming and see what happens. I know it was dirt simple, probably a temp add-on and a normalizing factor to suit the particular resistance thermistor. Sam

 Re: The lost formulaMessage #9 Posted by Pal G. on 18 Jan 2011, 2:16 a.m.,in response to message #2 by Martin Pinckney Quote: If anyone understands the meaning of this thread, I would like to know. 42.

 Re: The lost formulaMessage #10 Posted by Martin Pinckney on 18 Jan 2011, 8:33 a.m.,in response to message #9 by Pal G. Now that explains it!

 Re: The lost formulaMessage #11 Posted by Walter B on 18 Jan 2011, 9:54 a.m.,in response to message #10 by Martin Pinckney Don't lose your towel, ask Douglas Adams instead ;)

 Re: The lost formulaMessage #12 Posted by Dan W on 18 Jan 2011, 8:47 p.m.,in response to message #11 by Walter B When I first discovered WolframAlpha, I had to ask it the question of life, the universe, and everything. It came up with the correct answer. ;)

Go back to the main exhibit hall