Date:         Tue, 9 May 1995 11:30:58 -0500
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Stephen Serafin for Malek <serafin@ece.utexas.edu>
Subject:      Re: Aftermarket Electronic Ignition

In response to my suggestion that home brew exhaust
analyzers cost more than ~$50 John wrote:

>$250??, now not to sound crazy but dad just bought a nice
>4 digit handheld Fluke for $80 with capacitance meter as
>well, a nice little feature, come on we're tuning a bus
>here I figure just about any old DVM would be sufficient
>precision isn't really that necessary in a 1 volt range,
>hell you can get a data aq. board for $250 with 12 bit
>precision if you really wanted.  Admittedly I haven't
>tried it but I bet a cheapo $30 Radio Snack meter would
>do as well as the $300 bench model HP I happened to use
>when fooling around with mine.
>
>John Anderson (still trying to save you money)
>ja@coe.wvu.edu
>'71 Westy, '90 Corrado
>
I agree, many good DVMs can be had for less than $250.  Some of
them still go for $750 or more.  I do not know what the
requirements of metering the O2 sensor are though.

When I worked at an Amoco Research Center it was very important
to match the metering equipment to the sensors.  Even the type
wire used and its length had to be correct.  Otherwise data
could not be correlated.  Since the sensor produces a voltage it
is important to draw the appropriate current when measuring the
voltage.  All meters will draw some current.  Drawing too much
or too little may influence the reading dramatically.  The main
point is that the accuracy has to be appropriate for the sensor
being metered.  

The $80 dollar Fluke may or may not be appropriate for the job.
The Haltech meter will definitely be appropriate.  With the
specs on the accuracy required, current draw information, and
any other relevant requirements, a lower cost option may be
available.  It may even be that the accuracy can be horrible
and you can still get acceptable results.

I would be interested in having my own analyzer so if someone
has the information on a correctly matched system please post
the details, part numbers, wire type and length, etc.  The
ExhaustAnalyzer file has a lot of hints but it does not conclude
on an accurately working system.

Stephen
`75 bus