variable pot with a fine trimmer

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Dean Huster
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Post by Dean Huster »

MrAl- Do you think those 18 decimal places are sufficient?
I'm certain that MrAl foresaw that had he used only one or two significant figures in his posting, some omniscient clown would have "corrected" him to many more significant figures. Haven't you been watching the Ocean Spray commercials? "Well, it's more like a thousand times."

Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.
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dacflyer
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Post by dacflyer »

rshayes >>> thanks for the insight..
according to the info on the ICL7107 they say for setting 2.0 volt scale
that a 20k pot and a 24k resistor is to be used.

5 volts to the 24k resister to the pin 1 of the 20k pot, and the pin 3 to the ground.

i am not trying to get a full scale reading as thought..but close as can be for a normal thermometer.. like -10°F to about +120°F
but i find that the readings drift as it gets too cool or too warm past
85°F or so..but i can live with a few 10th's of a degrees off.

and the LM34 i use is having a 5 volt source.

i think, but am not sure if i understand fully, on what is suggested to use for the pot and/or resistor combo.. i am beguinning to see that i should not use a fine adjust.but rather find / figgure out the right resistor and pot to use.. as the paper states,,but i have to order some 15 turn 20k pots 1st..

feel free to enlighten me more..it seems you know this thing better than i do.. if i get this right, i will want to make more than one.. thanks.
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jwax
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Post by jwax »

Dean! Omniscient clown? On THIS FORUM?
Say it ain't so!
:razz:
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MrAl
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Post by MrAl »

Hi again,


Jwax, please, dont make me get my N digit calculator out, which can
easily calculate same to 500 digits or more :grin:

Actually, i wanted to make sure anyone reading knew it was a
calculation and not a measurement.

BTW, i did it with my free Scientific Function Calculator, which is
available for free download...
LEDs vs Bulbs, LEDs are winning.
Will
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Post by Will »

Mr Al,
Where is the free scientific calculator download free from ? Thanks
BB
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MrAl
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Post by MrAl »

Hi Will,

Here it is:

http://www.rapideuphoria.com/mafc-103.zip

Let me know if you have any suggestions or ideas to improve it.
Make sure to read the readme file before using, and there are
two Help files that should be looked over too in order to get
the most out of it.

With this kind of calculator someone can send you formulas and
you can 'read' them with the calculator and use them as if they
were part of the calculator. Comes in very handy.
Included are some EE formulas too.
LEDs vs Bulbs, LEDs are winning.
Will
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Post by Will »

Thanks Mr Al
BB
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MrAl
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Post by MrAl »

Hi again,

I should have mentioned that the Sci Calculator is made for
the Windows platform, and has been tested under Win98 and
WinXP.
It's free and it's always going to be that way so enjoy :grin:
LEDs vs Bulbs, LEDs are winning.
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ptribbey
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windows potentiometer/voltage divider calculator

Post by ptribbey »

I found a nice small calculator for free download.
I used it a couple times on my projects, and it works great!
Thank you to the author.
It is at:
http://www.yadtel.net/~ccp/potdesign/

Good luck
Paul
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