Top resistors

crocodile clip is chiefly British - http://en.wikipedia.org/wiki/Crocodile_clip

Moving on... it doesn't look to me the tip is attached to the lead, but I guess it could be; looks floating from this vantage point. Another interesting question is, why is he using the "alligator" clip in one but not the other; why wouldn't he be using the same thing on both ends.

More to the point though, do you really believe a resistor would truly measure differently based on "direction", as if it has some sort of partial diode effect? And the person who posted that link said it all made sense to him - what exactly made sense?

The typical O-Scope probe has a ground wire(with an alligator clip), that connects to the side of it's insulator body. The heavily protected(insulated) retractable hook probe, then can be connected to any lead, within(say) a component's chassis, for testing at various points in it's circuitry. All the resistors, shown in the pictures(of Mr E's site), are wirewounds. That means they contain drawn wire. Metallic wire molecules are of a crystaline construction and assume a directional, chevron shape, when drawn(ie: >>>>>> ). It's inferred by many, that the boundaries of the crytals can/will act as diodes, and may be the reason wire seems directional. That(partially) accounts for the popularity of Ohno Constant Casting(OCC or Mono Crystal), copper or silver wire, in the construction of cabling and interconnects.

OOPS- Make that Ohno CONTINUOUS Casting. BTW: I'll bet that the Bulk Foil and Nude Vishays, or Caddock Precision Films, would not show as dramatic a directionality, if at all.

Could this also account for the "directionality" in fuses some claim to hear? Any idea if the HiFi Tuning fuses are [P]OCC or not?

Regarding the oscilloscope waveforms shown at the link Eherdian provided, I'm not sure how they prove anything about anything.

It seems to me that the differences shown for the two orientations mainly involve interplay between the following factors:

1)The difference between the impedance between his fingers and one end of the resistor, and the impedance between his fingers and the other end of the resistor. Each of those impedances being comprised mainly of capacitive coupling between his fingers and the resistive element, plus some fraction of the total resistance of that element.

2)The impedance of the leakage path between the probe's ground and the scope's AC power input. Note that the time scale on the scope is 10 ms/division, from which it can be seen that the "signal" is comprised mainly of 50 Hz (he is evidently in a 50 Hz rather than 60 Hz country).

3)The input impedance of the scope/probe combination (i.e., the impedance that is seen "looking into" the tip of the probe, relative to its ground).

4)The relation between the value of the resistor and the input impedance of the scope/probe combination.

5)The impedance from his fingers through his body and through any path that may exist from there to AC/earth ground.

I see no reason to expect the net result of all of that to be equal for the two orientations, regardless of whether or not the resistor would have directional characteristics when inserted into a circuit. That conclusion would be true even if he managed to grasp the resistor exactly at its mid-point, due to the differences in AC leakage to the probe's ground and its tip.

BTW, although I haven't taken the time to read a lot of the posts in this thread, I happened to notice the one dated 10-22-12 from Larryi. As is almost invariably the case with his posts, it strikes me as being technically plausible, ringing true, and being an important point.

Regards,
-- Al