Re: Effect of the supply internal resistance
- From: "Shaun" <scepp@xxxxxxx>
- Date: Sat, 7 Feb 2009 18:51:49 -0600
The supply internal resistance will give you a voltage drop, lowering the
source voltage available at the battery that depends on the current you
voltage divider and load require. V(battery) = V(10 volts) - I *
R(internal). I is the total circuit current with your voltage divider and
whatever is connected to it. V(10 volts) is your open circuit voltage.
Shaun
"Rich" <notty@xxxxxxxxxx> wrote in message
news:6v5el3Fi418aU1@xxxxxxxxxxxxxxxxxxxxx
I'm looking at voltage dividers. Trying to learn what I probably knew one
time.
Say you have a battery supplying 10v, and it has in internal resistance of
1 Ohm.
You connect it to a voltage divider network R1 and R2. R1 is 90 Ohms in
series with R2 which is 10 Ohms.
Vcc connects to one end of R1, Ground connects to one end of R2.
No load on the tappinp point.
There is 10V from tap to GND. There is 90V to Vcc.
Okay I get this. But the battery connects between Vcc and GND and that has
in internal resistance of 1 Ohm.
This makes it look like R1 and R2 are also connected together not only at
the tap point, but at their other ends.
Which of course produces a kind of obserdity because that makes irt look
like there is the same voltage across both R1 and R2.
Of course, as far as the battey is concerned, it's 10V across it does not
short through it's own 1 ohm internal resistance.
But anyway, when is that 1 Ohm internal resaistance going to be
significant in any way? I know there will be a voltage drop across it when
current flows and the battery terminal voltage will drop.
But why exactly to you pretty much ignore that internal resistance when
calculating voltages in a two resistor divider network?
But I think in times past for some reason, because of low internal
resistance of the supply, Vcc and GND have been taken in some way as being
connected. I've forgotten now what that was.
.
- References:
- Effect of the supply internal resistance
- From: Rich
- Effect of the supply internal resistance
- Prev by Date: Re: Astable Multivibrator - why does it break down?
- Next by Date: Re: Effect of the supply internal resistance
- Previous by thread: Re: Effect of the supply internal resistance
- Next by thread: You need only a basic computer knowledge!
- Index(es):
Relevant Pages
|
