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printed inductors

J

josephkk

Jan 1, 1970
0
I've seen them on the plastic PCB used in a laptop keyboard. One on
each line, for no obvious reason. Keyboard row/column scanning can't
be time-sensitive that way.


Regards,

Uncle Steve

It could well be that the person that did the keyboard layout thought it
looked "cool" and had no idea about its functional aspects.

?-)
 
J

John Devereux

Jan 1, 1970
0
Uncle Steve said:
FK, I dunno. As far as I could tell they were redundant.

I wonder, could they possibly limit ESD current? A (very) poor mans
ferrite bead?

You see all sorts of interesting structures on mass-market boards, like
spark gaps on power supplies or a telecoms interface.
 
T

Tom Del Rosso

Jan 1, 1970
0
josephkk said:
That is not an inductor, that is a delay line (transmission line
type).

No, I didn't ask about printed delay lines. I asked about the behavior of a
particular type of inductor, used as a choke. They do exist.
 
J

Jamie

Jan 1, 1970
0
Tom said:
Sorry, but it's true...

We use square zing lanes for two reasons...
Delay and reduction of e-line propagation of near by fields.

Have it your way, but that is how I've understood and used them for years.

Now of they were circular in a square location, then that would
constitute an inductor.

You can argue all you want about it. It won't change anything.

Jamie
 
T

Tom Del Rosso

Jan 1, 1970
0
Jamie said:
Sorry, but it's true...

No it's true that delay lines are ALSO made that way, but on the board I'm
talking about it's a choke. It's conncted to the power supply. You do not
connect to power through a delay line.
 
T

Tom Del Rosso

Jan 1, 1970
0
Fred said:
Le Sun, 19 May 2013 17:14:38 -0400, Tom Del Rosso a écrit:



Sure you can. Just make it lambda/4.

You can use a delay line to connect power? What are you delaying?
 
T

Tim Williams

Jan 1, 1970
0
Fred Bartoli said:
....
At lambda/4 a shorted line gives Zin= Zc Tan(Lr) with Lr->pi/2 and
transforms the s/c into an open circuit.

Obviously, at DC it's no more lambda/4 and Zin=ZL=0.

This obviously doesn't hold for wideband signals.

^^ You see it all the time on microwave stuff. Wikipedia has a picture of
a... 20-some GHz satellite board, stubs and filters and amps all over.
Looks cool. They use thin 1/4 wave traces as bias tees all over (usually
with some additional LC bypass and filtering action, too).

Tim
 
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