X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient: geda-user AT delorie DOT com
Date: Tue, 15 Apr 2014 19:54:25 +0100
From: Richard Bown <richard AT g8jvm DOT com>
To: geda-user AT delorie DOT com
Subject: [geda-user] printed meter shunts
Message-ID: <20140415195425.37808583@richard-laptop>
Organization: Ham radio
X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.20; x86_64-pc-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-Provags-ID: V02:K0:gLXSZQtASuB1N/Z/gM+T5XPEBViq+ExB1V/ragvamAC
 Gey6b2qqcXIEaCSxSSOadzpqrfhhKSQRJidNzBmfLyj7yTGOOD
 iwggOdATRH+vUCFfI+uXL7hFGKLX1XO6ZOPtx23VmyaEsSYPtv
 kdIRK1z948de0JUGn2Cwbce1iDaSH1dgtDlsM0BCe1jnrJuZVE
 gy7YfEqTVU7KVuqWZxVXl8t6jL1OKEAbQfQ01ZOgGaF6tZMf35
 7gISlUZk9qnqUTCWhKYs/djpG6hI08PJknC7onRT2MRIB9KiRD
 gPqa4z7q71JmquR8/PpYyRbgD883zAn/I7TcRUle7PtKjMGve3
 a9JGuKhxXP0hwFFU9C2ekywGwiwQnwaONNMQXwrp8
Reply-To: geda-user AT delorie DOT com

Hi,
I thinking of playing with the LTC1645 using its for over current shut
down,
it requires only 50mV across a shunt resistor to trip, at 10A thats
5milli ohm.
And those resistors in TO-220 packages are expensive, so I was thinking
why use a length of wide track, needs to wide as handling up to 10A .
Are there any tables to give track resistance if the thickness , width
and length are known.
In practice its better to go for a lossier track and tap the voltage
across it with a potential divider, so target around 10 - 20 milli ohms,
cant use anything bigger as the board will get hot, 10A through 0.02 R
is 2 W, so better around 0.01 R

Thanks

-- 
-- 
Best wishes /73
Richard Bown
Email : richard AT g8jvm DOT com   
HTTP  :  http://www.g8jvm.com
nil carborundum a illegitemis
##################################################################################
Ham Call G8JVM . OS Linux Mint 16 x86_64 on a Dell Inspiron N5030 laptop
Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W
QRV VHF 6mtrs 200W, 4 mtrs 150W, 2mtrs 400W, 70cms 200W
Microwave 23 cms 140W, 13 cms 100W, 6 cms 0W & 3cms 5W
##################################################################################