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Re: data search.. RL circuits examples





On Thu, 25 Apr 1996, Alex. F. Burr wrote:

-
Essentially all RC circiuts filter of time. Annother application is
setting tyhe frequency response of FM radios (filtering). In the
FM radio business one talks about a 75 micro-second filter.
-
The time constant for your components is 2.2 s, a bit short for
a DVM. Try getting a 1 farad capacitor (from Digikey for less
$10) or use the largest C and R you have.

Try using the CBL with a program that triggers the taking of data when
the voltage on the probe exceeds 0.2V Run the program with the cap being
shorted out. Then, remove one end of the shorting wire and connect it to
the battery to start the charging of the cap. You should get good data
and the graph should look great. The ULI version of the expt should also
work but the availability of CBL and the triggering option is ideal.
Charlie


-
One time constant is the time necessary to charge a cap to 63%
of its final voltage. The 10 and 90 % points you mentioned are
used for measuring rise (and fall) times. They are related to
time constant but are not the same thing.