> No.  Like I said before, if your power supply contains bipolar
> transistors, then it's all BASED on current, since bipolar transistors
> are current-controlling devices.
>
> There's this big transistor on the back, probably on a heat sink.  The
> power supply allows the base current of that transistor to rise
> (increasing the collector current as well, but the beta factor) until
> it senses that a reference voltage has reached a correct value.  In CV
> mode, the reference voltage is just the output voltage  In CC mode, the
> reference voltage is the voltage across some current-sensing resistor.
> Your linear regulators (7805, etc) work the same way.  The internal
> components are controlling current, rather than voltage directly.
>
> A transistor is a fine example of a device that permits current to be
> controlled directly.  Bipolar transistors are current-controlled, FETs
> are voltage controlled, but in each case it's the current that is being
> manipulated.  (Come to think of it, tubes work this way too...)

It's probably my fault for not being clear enough
about what I was asking, so I will make one more attempt
(I promise - this is my last post!).

I am not saying the algebra is wrong.  I am not saying
that at any given time it's not convenient to put any one
of the three variables on the left hand side of the
equation.  I was just trying to understand how current
could be an entity in its own.  This was my understanding
and I guess you're saying I'm wrong:

  - You can have V without I
  - You can have R without I
  - You CAN'T have I without V and R

Thanks for the responses. (I will now unsubscribe from the [EE] tags and stick with [PIC] ;)).

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