interesting question. maybe you've heard it before?

[omieschmomie]

What is common between a diode and pulley?
It's an electricity question.

Come on Nukes! Let's see what we got.

[bsdnuke]

one way diode, two-way pulley

[rlbinc]

Let me take a shot at it. A pulley and a diode can both make a machine that causes vector reversal.

1) I can pull DOWN with a pulley and lift a weight UP.
2) I can put a NEGATIVE half sine wave into a full wave rectifier and get a POSITIVE half sine wave out.

Taken a step further...
1) I can get current flow through a forward biased diode (electron motion). But I can't get current through a reverse biased diode (no electron motion). (Unless it's a Zener, they cheat.)
2) I can pull on a pulley rope and raise a load (motion) above a floor. But I can't push on the pulley rope and lower the load past the floor 9no motion).

How's that?

[omieschmomie]

excellent job rblinc