Homebrew PCBs

On Thu, 5 Feb 2004 02:19:42 +0000 (GMT), jagjot singh 
<mundasocute2000@...> wrote:

>
> Hi friends ,
>
>                Thank you so much for the reply . I was wondering how do 
> you actually calculate the width of the trace specially for high 
> currents ( say 30A ) and high frequencies .
>
>

there are two parameters, one is the heat generated and the other one is 
the voltage drop.

obviously the heat will destroy the track if too much, you can simply 
calculate with the resistance
of copper or use the tables. you want loads of security margin here.

Also keep in mind that thin traces can act as a fuse. It has already saved 
me some valuable
components this way. but the fuse is ugly after it is needed and not 
replaceable.


Voltage drop: in some occasions the voltage drop is more important, if you 
do the circuit
design yourself then you know where this is important. calculate with 
resistance and current.

<http://www.eese.bee.qut.edu.au/students/protel/pcb_manufacture.shtml>

here you can see one chart for track width.

I have the habit of soldering additional copper wire on a really high 
current track.


High frequencys:

the skin effect is not a problem because the track is broad (and thin) i 
think.

look here

<http://www.polarinstruments.com/support/cits/AP171.html>

Make no antennas, keep inside area of loops small.



Always use plenty of security margin!


good luck

ST