Analog Meter capability

[Tom Cloud]

>I was thinking about setting up a GM MAP sensor on my Camaro, complete
>with a 5 volt signal, and trying to obtain some data relating manifold
>pressure to throttle position and RPM.  

what's wrong with a plain ole vacuum gauge ??  -- or are you wanting
a "real" electronic signal ??

>Would an analog meter with 10k internal resistance require more power
>than the sensor would put out?  I have a small 10 meg internal
>resistance voltmeter, but I don't think this would work well. The
>digital meter display wouldn't settle down enough to take readings.  The
>analog would tend to dampen out some fluctuations.

first you say 10k and then 10M  --  I, personally, don't have a
clue as to the Zout (output impedance -- or ability to provide current)
of the MAP sensor.  I'd suspect that it was lower than that of the
EGO sensor though.

typical DMM has 10M Zin.  typical VOM has 20k ohms/volt (unless you
get it from ratshack .... then maybe 5k or 10k ohms/volt.  If the
analog meter has an internal amp (does it need batteries for more
than the ohms scale ?), then it will likely also have 10M Zin.

The analog meter would definitely "smooth out" the reading so
you can more easily see trends, etc.

Here's how to find out the answer to your question:  put a known
vacuum on the sensor and measure it with the DMM.  Then, measure
it with your analog meter and see if it's significantly different.
(Of course, if the Zin is 10M then there's no reason to do this,
it should work okay.)

Tom Cloud

     Madness takes its toll   .....   please have exact change