[sdiy] Using SSM2164 in stereo

[Walker Shurlds]

On Thu, 21 Jan 2010 08:15:38 +0100
cheater cheater <cheater00 at gmail.com> wrote:

> > The electrons lose potential, but the same number of them flow.
> 
> But an electric potential of a conductor is defined by the amount of
> electrons in that conductor. How do electrons 'lose potential'?

Potential of an electron has to do with its energy state, compared to
the default energy state.  Voltage is the average of these energy
states for all electrons in the conductor.  At one end of a voltage
source, all of the electrons are in a higher energy state, and to do
work, they move to a lower energy state, at which point they arrive at
the other end of the voltage source.


> And if potential is lost (= electrons are lost) how are we conserving
> the current across the resistor?

No electrons are ever lost.  As electrons do work, they lose potential,
the same way that when you roll a ball down a hill it loses it's
potential energy, but the ball never vanishes.

> I understand the current on the output of the current source stays the
> same. But that does not imply that the current at 'the end' stays the
> same, does it? I thought current sources were infinite charge pumps
> that terminated in ideal sinks. That just might be me, though, so
> correct me if I'm wrong.

I don't know exactly what you're saying.  The current going into
anything is the same as the current going out of it no matter what.
Ideal current sources have a constant current, therefore sticking a
resistor in front of it results in a voltage.

If you put a current source right up to a high-impedance input, the
result is going to be constant current * high impedance = high voltage
= bad.

Hope this helps,
Walker