RE: Data Acquisition

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Wow Dave!!!!!!!!!  You ain't messing around ;-))

For capacitance, just set up a little 555 CMOS timer with a solid stable 
power supply voltage and use the C you want to measure as the C or the 
555's oscillator.  The 34970a measures frequency too ;-))  That 50% duty 
cycle oscillator in the data sheet (page 7) is good:

http://www.national-dot-com/ds.cgi/LM/LMC555.pdf

For L  Just a little LC oscillator with a stable C (npo, cog 
capacitor).  Again just let the logger do frequency and back calculate with 
Excel or Open Office to find the C and make those pretty graphs.  Could 
probably make a 555C oscillator that uses L instead of C too...

I am not familiar with "Hall stuff", but if it has an "output signal", the 
34970a can measure and record it with stunning ease...  Just import the 
data to a spreadsheet program to play with it all you want.

The software for the 34970 is a freebee and can be downloaded at:

http://we.home.agilent-dot-com/cgi-bin/bvpub/agilent/reuse/cp_ObservationLogRedirector.jsp?NAV_ID=-11250.536881544.00&DOWNLOAD_OR_LINK=2&TARGET_CONTENT_OID=536915194&TARGET_URL=http%3a%2f%2fwe.home.agilent-dot-com%2fupload%2fcmc_upload%2fDataLogger1.5.030305.EXE&SRC_PAGE_NAME=%2fagilent%2feditorial%2fcp_MiscEditorial.jsp&SRC_CONTENT_OID=536915195&CONTENT_TYPE=AGILENT_EDITORIAL&REF_LABEL=BenchLink+Data+Logger+Version+1.5.030305&LANGUAGE_CODE=eng&COUNTRY_CODE=ZZ

Yips!!  That is supposed to be "one" line ;-))  I think there are more 
variables there than there are sub-atomic particles in the universe...

Just go to:

http://we.home.agilent-dot-com/

and search on "1.5.030305" which is the software part number.  10.6Mbyte 
download.  It has demo and simulation modes if you don't have the logger 
there.  Unlike some obnoxious vendors like Tektronix, this software is the 
full no holds barred production version!!

If you have windows 2000, you might want to dig into the serial port setups 
and turn the buffering down to "full reliable" settings as opposed to the 
"fast, but looses all your data" settings (virtual driver goofyness...)  HP 
serial cables are slightly odd, to so try and get the official HP cable if 
you can or just wire your own.

BTW - I will be calling Agilent "HP" for the next 200 years...  Brain just 
can't change...  HP was easier to spell too ;-))  So forgive...

And Dave, don't go getting any test equipment that is "better" than I got 
either!!!  >:o)))

Cheers,

         Terry



At 04:24 PM 1/19/2004, you wrote:
>Hi Terry, Jan, and all,
>
>Thanks for your many suggestions.  I located a HP 34970A and 34901A card at
>a reasonable price.  Now how do I go about using a 555 timer for measuring
>magnetic field, inductance and capacitance?  Is there some way to rig Hall
>effect chips to measure the magnetic field that isn't too complicated?
>
>Dave