Rick Hughes wrote:
On 01/01/2013 21:35, wrote:
wrote:
As part of another project, would like to take some High Current DC measurements.

I have a couple of multimeters ... but obviously not going to be any good for around 80-100A

Now going back to school physics lessons I could use a Shunt resistor ...
http://www.societyofrobots.com/robot...?topic=13900.0

The issue will be obtaining a suitable shunt ... assuming I use a 1 ohm shunt, anybody made one of these ?
The WEB ref page:http://www3.zetatalk.com/docs/Electr...Meter_2007.pdf
details using 12guage copper wire .. based on 1.619 ohm per 1000'

Although maybe a resistance wire may be better eg Nichrome around 10.58" for 1 ohm.
Welcome to any better ideas.

A much more elegant (and still DIY) method is to use a Hall Effect
device, no direct connection to the circuit being measured at all. The
bigger devices (from 50 amps or so upwards) are just toroids through
which you feed the current carrying wire.

Available from CPC, Farnell and others. Devices such as HTFS200-P and
LTFS 50-NP should take you where you need.


Never used these ... are they passive and direct interfacing to a DVM,
or do you need driver circuitry ?

They vary a little in their requirements but the simplest just need a
5 volt supply and then you can measure the output with a DVM. Take a
look at the data sheets at Farnell.

--
Chris Green