LCmeter history...

You can build a free LCMeter at:

http://xavier.fenard.free.fr/LCMeter.htm

you can find all files: HEX, PCB and source.

It's work with the shift of the LC oscillator, and give the % that the same
commercial product...


The history is long, the AN41 (1970) was the start of a lot of projets... in
70s.
All people use the same value of compoment than give in AN41, but it's not
critical, 100K or 120K or 82K.... work fine also, 100k the "tradition" . I
dont know the father of this AN41. But after, in OM (world and england an
french..) a lof of variation, specificaly in Xtal// (low freq), on the +
pin, for exemple in 76, in article on collection of xtal osc (low to high).
This is not the better circuit for the class of LC very large L/C
possibility but it's compact.

The better is (me and the people who compare) (originate of a other AN
but...I dont remember who, its in my papers...) a transistor solution, go
much Freq+.

This circuit has been used for an other LCmeter (Fx,periode...), more
complex from F.thobois (describe in the french revue le haut parleur in the
80'), after a kit will be sold... a mistake of F Thobois? because he give a
lot of a the projet
at http://home.nordnet.fr/~fthobois (FRENCH and ENGLISH) (R/C plane) where
you can see the big LCmeter TFX4 (no relation to me ...FX!). Because the
multimeter dont give L, but C recently,a paper on a L meter only, supply
only by RS232 and give the result on PC...

My conclusion is, a lot of time before, and now (?) the OM give to the
communoty, for build, modify, and ameliorate his projet, or he don't give..
Have you see a OM schematic with no value of compomment?.
Now, with the processor, this include also the prog. Its not be a BLACK BOX,
its important for the LEARNING.

The most parts of software is by "
; ** FAST IEEE FP Routines for Atmel AVR RISC **
; ** 1998,1999 by Jack Tidwell <> **
; ** These routines may be used for personal and educational
; ** purposes, and are free to download. **
who I think have the same opinion of me, personal and education, not?.
It will be the start of my new, compact, lowcost, easy_to_build (Only one
face PCB) LC meter
you can adjust the value of L,Cref it's the two first float numbers in the
flash EEPROM AVR!.
I explain in a paper (onde magazine) why the atmel is powerfull than the
pic, that i used also. Try to put a float lib in a space of 16F84! (aprox
same that ATMEL i use).
The drawing PCB comme from B.Urbani, a freeware ... you can modify the
PCB... you have also the "source".

I appreciate all the think to ameliorate the project, but I dont want to
discuss of the father of a circuit, it's the AN41 because I dont know one
other before 1970 of le LM3(1)11 oscillator.
The people of italian country is also very good, all country in fact.
Sorry for my english...
XF

PS: AOL, TISCALI, WANADOO are web provided, FREE (french yes!) also, it's
all, a low cost. Not relation between free and free..

 

No one would (or should) use the 16F84 today. It's old, costs a lot, and
has been
replaced with several generations of new PICs. How old is the AT90S2313
you
are using ?

I'd probably select use one of the 18F-series PICs. There are absolutly
no problem with float libs in (current versions of) PICs !

Jan-Erik.

 

Yes the 16F84 is old, but a lot of project use it because its easy to find.
The data sheet for the AT90S2313 is 2000. Its take 1 cycle for one
instruction, (4 for the pic),
and you dont have a W register, its same as DSP (ex R3<R3+R4).
The pic, for exemple, the 16F87x is very interesting, you can reprog the
flash.
The next step the 18F is not easy to find.
yes with more space than the 16F84, the float lib is ok, but for the
LCmeter, i want to use a small chip
(mot 12C508). The ATMAL can do the two: Float lib and small (20 pins)/ 28
16F87XX.
XF