[ot] use of a long coaxial cable <OT>

[Ric Moore]

On Sun, 2007-01-21 at 22:16 -0600, Alma J Wetzker wrote:
> Ric Moore wrote:
> > On Sun, 2007-01-21 at 06:53 -0500, David Bandel wrote:
> >> On 1/21/07, Ric Moore <wayward4now at gmail.com> wrote:
> >>> On Sat, 2007-01-20 at 20:38 +0800, Man-wai CHANG wrote:
> >>>>> 10base2 is 50 Ohm.. period.
> >>>>> 75 Ohm is probably (cable) TV or radio.
> >>>> Do we need special equipment to measure impedance? I have forgotten my
> >>>> A-Level physics... :)
> >>> Just an Ohm meter...
> >>>
> >>> E = I times R
> >>> Energy = Impedence times Resistance  which translates to:
> >>> Volts = Amperage times Ohms.
> >>>
> >>> I've always wondered why they changed all the words?? Who and When?
> >>>
> >> They may have changed some of the words at some point, but resistance
> >> and impedance are not the same.  Resistance is static.  Impedance,
> >> however, is not static, it changes depending on frequency.  You don't
> >> just measure impedance with an ohm meter.  Consider yourself gonged.
> >> Show's over for you.  Please leave the planet.  Resistance is futile.
> > 
> > JEEEEZZZ! Dang me. You measure resistance (ohms) with an ohm meter and
> > the impedance (amperage) with an ampprobe. Why they changed up the words
> > is beyond me. 
> > 
> > Man-wai, the deal is when that Ohm's Law equation came out, they used
> > the words Energy, Impedance and Resistance.  Now they are:
> > 	Voltage, Amperage and Ohms.  
> > 
> > Yet, Ohms law is still written as  E = I X R ...out of respect for the
> > old geeze who figured it all out for us. You're supposed to be
> > enlightened to the point of doing the conversion in your head. Thanks to
> > Meester Senor Bandel of Panama for pointing out my faux paux. <smiles
> > grimly> At least he'll be old and grey someday too... falling face first
> > into his oatmeal. I get no small measure of satisfaction from that fact.
> > <smirks> Ric
> 
> True, you do measure resistance with an Ohm meter.
> 
> You *cannot* measure impedance with an Ohm meter.  You need some special
> equipment.  In lab, we did it with a frequency generator and and
> oscilloscope.  VERY simply, Ohms work for DC and impedance is for
> everything else.  Impedance is a function of frequency. [R(f)]
> 
> In my current class, even Ohm's law is not fixed.  Thanks to a guy named
> Maxwell.  The 'E' in Ohm's law stands for Electro-Motive Force, or EMF,
> what we usually now call voltage.
> 
> We need to stop this thread before one of my professor's sees it and
> goes back to change my grade.  That would be bad, I am done in May.

They call me Sparky, 220 440 880 is the voltage ranges I play with, not
this little itty bitty etched stuff... oh hell nah, double ought. I eat
nails and pass lightning.  Ohms work just fine in a series circuit.
Covert the wattage rating (PIE) so I can get the ohms I expect to read
in a coil and that works for me. The winding will be good, shorted or
open. Nice and simple. I like my electronics to make really big sparks
and blow the tip of my screwdriver off... "real good". Everyone else
runs for cover. 

When I was in my 20's my soon-to-be "step-dad", the MASTER Electrician
had strung 4 light sockets over head in a pole barn.
"Rick-ah-ey" (ALabama) One of these sockets ain't workin'... can you
check 'em?" Not volt meter anywhere in sight. Right, I'm seeing this
picture. So, I walked along sticking two fingers into each one and got a
jolt on #'s 1,2,4 with 3 being a no shocker. I just kept my finger in
number 4 and calmly told him "...this must be it, nothing." I got the
eyeball for several seconds and so Mr. MASTER Electrician comes up and
sticks his finger in number 4, just like I planned. "YEOW!" I said,
"Damn, I didn't get anything at all on that one." and looked all
innocent. He said that he thought it was number 3. <sly grin> The juice
has just never bothered me, not that I'm gonna jump into a substation
with a running garden hose, a bag of rock salt and a trampoline. Nah...
I'm not a MASTER Electrician either. 30 some years later, he still gives
me this sideways look. Go figure. Ric


Ric aka Sparky
 

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My father, Victor Moore (Vic) used to say:
"There are two Great Sins in the world...
..the Sin of Ignorance, and the Sin of Stupidity.
Only the former may be overcome." R.I.P. Dad.
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