Re: Internal resistance

[Bernard Cleyet <anngeorg@PACBELL.NET>]

L!

Your regulator has died.

You've got a typo in the second row (V1 column).

It's difficult to do the R(int),  as you have only enuff data for one
point at each V, and for only two of them.

Can you obtain a slide wire pot.  One of these big Cenco things with an
alumdum cylinder wrapped w/ wire and a sliding contact on the top guided
by a triangular cross section bar; it's the variable connection.   Then
take several points at one voltage and repeat for several more V's (open
circuit) as desired.   Plot, I -V for each initial (open circuit) V, the
family of lines (curves).

From the two EMFs (OC V's 6 and 16) possible to find the "dynamic"
resistance.  I calc., respectively, 1.19 and 0.99 Ohm.

The regulation is ~ 30%  at each V.

bc

p.s. ensure you wire in four terminal configuration.  I forgot on my
first trial.

Ludwik Kowalski wrote:

> To late to think (it is 10:30 p.m. I stayed in the
> lab to collect data). But here are row data that
> I just collected. All at the same room temp.
>
> Circuit consists of a regulated power supply
> on whose terminals there was a volt-meter in
> parallel with a branch containing a resistor
> R, an amp-meter and a switch.
>
> Notation:
> Vo volts measured when I is zero (switch off)
> V1 when switch is closed (I as indicated below)
> I current measured current (switch on)
>
> 1) Results for R1 (nominal 2.8 ohms, 12.3A)
> Vo=6.0   V1=4.2    I=1.33 A
> Vo=10.0   V1=2.2    I=2.39 A
> Vo=16.0   V1=11.7    I=4.00 A
> Vo=20.0   V1=14.7    I=5.06 A
>
> 2) Results for R2 (nominal 21.5 ohms, 4.4A)
> Vo=6.0   V1=5.5    I=0.24 A
> Vo=10.0   V1=9.3    I=0.42 A
> Vo=16.0   V1=15.0    I=0.67 A
> Vo=24.0   V1=22.7    I=1.03 A
> Vo=30.0   V1=28.3    I=1.28 A
>
>
> On Thursday, April 1, 2004, at 10:04 PM, Bernard Cleyet wrote:
cut