Current meter shunts

[Roger Geesey]

Surface mount chips are available in milliOhm resistance values suitable for shunts.
See:
NewarkInOne Part Number 07J6225
LRF2512-01-R025FTR  INTERNATIONAL RESISTIVE
Thick Film Resistor Series:LRF; Resistance:0.025Ohm; Resistance
Tolerance:+/- 1 %; Power Rating:2W; Temperature Coefficient:+/-100 ppm;
Package/Case:2512; Terminal Type:PCB Surface Mount; Mounting
Type:Surface Mount; Packaging:Cut Tape  $1.22  Quantity 1.

I've seen some 5, 10, 15 milliOhm parts at 1 Watt also, such as Digi-Key Part Number P15CT-ND.
Thick film construction yields low inductance.  The 2512 size makes easy parallel or series combining for lower temperatures.

Will Temco of 100 ppm work for you? (amounting to 1/2% with 50 C temp change).

73
Roger
_________________________________________
Hal wrote:
Date: Thu, 17 Nov 2005 08:40:24 -0500
From: hal <hfeinstein at cox.net>
Subject: Wind my own shunt?
To: tacos at amrad.org
Message-ID: <437C8848.6000308 at cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I need some advise on building an current/voltage monitor for my 12v/70A 
power supply
that powers my 300w 2m amp.   I know I need a shunt arragnement to allow 
more or
less full scale on a 1ma  ammeter.  The problem is building the shunt 
resistor. I checked
the 2006 ARRL handbook and it tells me I must wind my own shunt from 
resistance wire.
McMaster-Carr is a source for nichrome wire  of various diameters 
(thanks to Sandy and Dr Bruhns) but honestly, isn't there a modern way 
to tackle this problem that does not involve
building a unique component from scratch? 

--hal wb3kdu