This is done is some high frequency circuits, to employ some inductive
reactance, and or to add some delay to a pulse or signal. I have also seen
traces done in a sort of coil to be an inductor. If the space is available,
it is easier to do the inductor as a trace on the board, rather than to
insert another component. This technique can also be a space saver in the
assembly.

I have also seen this done to add some resistance between two points. In
some cases to get something like a few points of an ohm, I have seen a trace
going all the way around a circuit board. When I worked for RCA industrial,
they were making some circuit boards where they were using extra lengths of
trace to have some resistance inserted. They also did a number of boards
where the small value type inductors were done with traces.

--

JANA
_____


"klasspappa[remove]" wrote in message
...
Its a cheap fuse.
I have seen it in a car radio, 3 tracks, one was burnt, just solder a
jump on tracks 2... as good as change a real fuse ;-)

Mr Nisse

meirman wrote:
I have a little power supply module, made in 1983, for a burglar
alarm, but I've seen the same thing on other printed circuit boards:

One of the metal traces on the non-parts side of the PCB has, in place
of the 1/10" and 1/16" wide traces used elsewhere on the board that go
to their destinations as quickly as possible, using straight lines, a
half inch of one trace is zig-zag, sort of.It's really not a zig-sag
since all of the angles are right angles, and none from Z's. Here it
is:

___ ___ ___
|___| |__| like this, except smaller segments, 2 or 3mm. Not

even in a critical spot, afaict. It's the lead from a resistor, it
looks like, that comes from an AC 12v transformer connection, to one
of the 4 diodes in a bridge rectifier setup.** The first inch of
this trace is straight for an inch, with a right angle and straight
for another half inch.

Why don't they just use a straight line for the rest also?

Thanks.

**(FWIW, the bridge is followed by a filter cap and I think a voltage
limiting transistor with a heat sink)


Meirman
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