multimeter advice needed

Don Holtz daholtz at axionet.com
Wed Feb 17 21:58:46 GMT 1999


Here is an idea:

Try using a current sensing resistor.  They are usuaully 1mhom (1E-3 ohm),
and a regular voltmeter.  Put the resistor in series with the load, and
measure the voltage across it.  For a 1m ohm resistor, 100A would read as
100A*.001 ohm=.1V  for 1A => 1A*.001ohm = 1mV.   These values are readable
by any resonable DMM, and the current sense resistors should be available
at any industrial electronic supply shop (ie.  Electrosonic in Canada).

Note:  I^2R=(100A)^2*(.001ohm)10W, so use at least a 10W resistor!


I seem to remember that inductive current meters only work on AC, not DC!

Cheers,
Don Holtz

=At 03:12 PM 2/17/99 -0500, you wrote:
>On Wed, 17 Feb 1999, James Weiler wrote:
>
>> Date: Wed, 17 Feb 1999 11:02:40 -0800 (PST)
>> From: James Weiler <james at brc.ubc.ca>
>> To: diy_efi at efi332.eng.ohio-state.edu
>> Cc: eec at eelink.net
>> Subject: multimeter advice needed
>> 
>> Gang,
>> I'm looking for a digital multimeter that can also read frequency (what 
>> range I don't know, anybody have any recomendations here?) and handle
current 
>> high enough to measure alt. output and starter draw so proly close to 100 
>> Amps.  Don't know if they come this high.  Proly my dream meter is a fluke 
>> but I don't want to hand over my first born and perhaps an appendage too. 
>> 
>> It would be ideal if it could measure current by an inductive pick-up.  
>> Don't know if all this is possible at a reasonable price, I may be asking 
>> too much.
>> 
>> Thanks for any and all advice,
>> jw
>
>I saw a meter in the back of Electronis Now or some such it did dwell,
>pwm, frequency as well as the more mundane things I'll try to track do 
>the ad ( it was a full page one as I remember)
> 
>
>Pat Ford                           email: pford at qnx.com
>QNX Software Systems, Ltd.           WWW: http://www.qnx.com
>(613) 591-0931      (voice)         mail: 175 Terrence Matthews          
>(613) 591-3579      (fax)                 Kanata, Ontario, Canada K2M 1W8
>
>
>




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