In a message dated 11/21/99 3:16:37 PM, boxweed@thebest.net writes:
<< Can any of the engineers in this group explain what the induction loop in
the wire that goes to the tach actually does? (I've also seen this loop in
some of the wires that go to the various components of my computer. Do they
serve the same purpose?)
TIA,
Bob >>
Bob,
Can give you the basic concepts for these loops. Starting with the loop on
the tach. The car is of course a DC electrical system and the wire on the
tach goes to the points. So every time the points close a current flows
through the wire. This is fairly fast so the current looks like a pulse. An
electrical pulse passing through a loop of wire creates a magnetic field.
The metal "clamp" that holds the plastic with the loop is part of another
loop which "see's" the magnetic field which then creates another electric
pulse which the electronics in the tach detects. Then through a magic black
box makes the needle on the instrument move. The magnetic field has a "North"
and "South" pole (or right and left pole for some folks) and it does make a
difference to the tach which pole it see's. That is way the direction of the
loop is important.
The loops in your computer are most likely to try and suppress electrical
noise spikes. Particularly if they are wrapped around a metal donut. The
ones that come to mind are on the AC power lines. That is unless you have a
really old computer with solid core memory.
Bob and Annice
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