Floating point expression looking for integer math solution

[Acetronics2]

Hi, Castor

May be there would be a smart turnaround ...

if , instead of R1, you use a constant current generator ...

say a PNP trans, with a red led between VCC and base, a resistor between emitter and VCC to fix your current ...
and another resistor between base and GND to allow, say, 1 mA into the led + trans base.

good idea, no ???

Alain

[paul borgmeier]

Short on time but this might get you started

Rewrite this
R2=10.000/[(5000/ad_res)-1]
to look like this
R2=10.000*ad_res/[5000-ad_res]

calculate the denominator and keep (5000 - ad_res)
Calculate the numerator (10.000*ad_res)
Use Div32 to divide the numerator by the denominator

Use Darrel's method to get the remainder

http://www.picbasic.co.uk/forum/showthread.php?t=1942

[skimask]

Or even easier (I think) to use a DS1820 type sensor.
There has to be at least a dozen examples here on the forums.

[Acetronics2]

Hi, Ski

Good idea ...

and if being really time-short a LM 35/335 ... could also do it !

But what replacement for my .5 mm dia thermistors ( from aerospace industry ) ??? didn't find yet ...

Alain

[Castor]

I used Paul's sollution and it works great !