Re: Q. re: CircuitMaker (Student)

"David L. Jones" <altzone@xxxxxxxxx> wrote in
news:f3f0720d-b5bf-4873-8c28-43bc45b7b988@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

On Aug 14, 10:01 am, Kris Krieger <m...@xxxxxxxxxx> wrote:
Hi, I'm fooling around with CircuitMaker student version. I'm
curious as to whether anyone can tell me why a battery is not both a
voltage source and a current source - I thought that current was
necessary to calculate re: powering things, so this is confusing to
me.

A current source provides a *constant current* into a load, (ideally)
regardless of what that load is.

A voltage source (or battery) will provide whatever current the load
requires. So while the battery is providing a current, it is not a
constant current source, as the current won't be the same with
different loads.

Oh...oh!, OK, because current is a function of voltage *and*
resitance...?


A voltage source provides a *constant voltage* into a load, (ideally)
regardless of what that load is. A real battery is a voltage source
with an internal series resistance.

Because no material is resistence-free, right? Whcih would be the reason
for Joerg's note that "If needed a little resistor is added to simulate
the impedance", right?

(Yes, I'm still in the Dummy stage... =:-o )

I can't remember how CircuitMaker
actually treats a battery symbol, best to use a proper constant
voltage source if that's what you really want.

It has a symbol that looks like the standard Battery symbol in hte
electronics texts, and you can choose to have the + and the - shown (good
for us beginners ;) ), plus you can specify teh VOlts. THe Default is
10V, but you can right-click and change that parameter to, say, 1.2V,
which is what I'm fooling with.



So a battery (or anything else) can't be both a constant voltage
source and a constant current source at the same time, they are
mutually exclusive.

Also, does anyone know whether I'd therfore have to add both a
battery, and an accompanying current source...?

Not together as the same source, no. You usually use either a voltage
source or a current source depending upon the sub-circuit you are
trying to simulate.

Dave.


OK, as I speculated in reply to Joerg, current changes because it's a
function of Volts and Resistence?

Maybe what I need to do is keep looking through my Google search (I'm
currently running a search of
"SPICE" AND (electronic OR electronics)
and look for refernece materials, becasue I'm starting to think that the
current-voltage question is both a fundamental and a peculiarity of the
software structure and how it handles Power (watts). What's confusing me
with the simulator is I finally <!> understood, after some helpful
explanations by folks in the "basics" NG, that *Power* In has to equal
*Power* Through/Out, so, a subcircuit can "finagle" amperage and
"convert" it into voltage, or visa versa, but in the end, Watts Equals
Watts (did I mention I was starting from Zero with tryign to learn some
electronics...?) ANyway, so I thought I could use a simulator to analyse
a simple circuit in a ways that follows that rule.

I'm Googling
("SPICE" AND (electronic OR electronics))
and looking for tutorials, references, and so on, so maybe I ought to do
that first, since I'm starting to think that I ahve soem fundamental
confusion re: what "Spice" is actually supposed to do.

Thank you for the info!

- Kris





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