On Apr 23, 8:50*pm, "Leo Lichtman" wrote:
"David Lesher" wrote: *(clip) the leak is proportional
to the voltage drop... and not just linearly.(clip)

^^^^^^^^^^^^^^^^^^^^^
Basically what you say is right, but I have to correct you on this small
nit: *Proportional *IS* linear.

An Ohmic resistance is linear but semiconductor behavior is often
exponential or logarithmic. A good example is the drop across a diode:
http://www.allaboutcircuits.com/vol_3/chpt_3/1.html
Scroll down to the part about kT/q.
The effect is that the voltage drop rises with the logarithm of the
current.

This one shows how the forward drop changes inversely with
temperatu
http://www.cryocon.com/S900/S900ds.pdf

In the 1980's 4-1/2 digit DVMs were very expensive and I built my own,
using a constant-current source for the resistance function instead of
the usual MickeyMouse shortcut that obscures the actual voltage and
current passing through the resistor. Mine forced 1uA, 10uA...10mA and
showed the true voltage. It would clearly demonstrate the logarithmic
VI curve of a diode, from ~400mV to ~700mV. Unfortunately my ex used
it to check her car and fried that circuit with 12V.

Jim Wilkins