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Active Filter Troubleshooting

The animation below shows the effect of varying C1 and C2 from .001 uf to .1uf on the frequency response of the Active Low Pass Filter. Use curve below for baseline information.

Troubleshoot Circuit Below

Determine the component failure which caused Fault 1 through Fault 3 shown by below plots. Select faulty component from list below. Hint: Do not give the same answer (1 - 6) twice.

1. C1 open

2. C2
decreased in capacitance(decrease less than 50%).

3. C1 Leaky.

4. C2 Leaky.

5. R1 open.

6. R2
open

ANSWERS AT BOTTOM OF PAGE

ANSWERS AT BOTTOM OF PAGE

ANSWERS AT BOTTOM OF PAGE

ANSWERS BELOW

Fault 1 Answer

No.2- C2 decreased in capacitance. (Failed C2 = .006uf )

ANSWERS BELOW

Fault 2 Answer

No.1- C1 Open

Note that with C1 open the circuit becomes a simple RC or first
order filter with an op-amp voltage follower. This results in
a reduced roll off rate of about 6db per octave

ANSWERS BELOW

Fault 3 Answer

No.4- C2 Leaky (R_{parallel}= 12k)

The voltage divider formed by R_{parallel }, R1, and
R2 causes the normally unity low frequency gain of this circuit to be reduced.