22.6: Procedure

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22.6.1: Band-pass Output

1. Assemble the circuit of Figure 22.5.1.

2. Calculate the frequency range, Q range, and band-pass gain of the filter. Record these values in Table 22.7.1. Note that \(R_t\) varies from 6.8 k\(\Omega\) to 56.8 k\(\Omega\), and that \(R_q\) varies from 680 \(\Omega\) to 10.68 k\(\Omega\).

3. Set Q to its highest value. This can be accomplished by adjusting the Q potentiometer for minimum resistance.

4. Apply a 0 dBV sine wave at approximately 1 kHz to the input.

5. Set the filter tuning to its highest value. This can be accomplished by adjusting \(R_t\) to minimum.

6. Sweep the input frequency until a peak output is found. Record this frequency and amplitude in Table 22.7.2.

7. Record the –3 dB, –6 dB, and –10 dB frequencies on either side of the peak, in Table 22.7.2. These amplitudes are relative to the level found at the peak.

8. Set the Q adjust to its lowest value (i.e., \(R_q\) at maximum) and repeat steps 4 through 7, using Table 22.7.3 to record your results.

9. Set the filter tuning to its minimum value (i.e., \(R_t\) at maximum) and repeat steps 4 through 8, using Tables 22.7.4 and 22.7.5 to record your results.

10. If a spectrum analyzer is available, verify your readings.

22.6.1: High- and Low-pass Outputs

11. Utilize the HP output.

12. Apply a 10 kHz sine wave to the input and adjust the amplitude for a filter output of 0 dBV.

13. By sweeping the input frequency, determine the −3 dB frequencies for \(R_t\) at both extremes. Record these values in Table 22.7.6.

14. Determine the attenuation slope by measuring the output signal amplitude using a frequency one decade below the −3 dB frequency. Record this in Table 22.7.6.

15. Utilize the LP output.

16. Apply a 100 Hz sine wave to the input and adjust the amplitude for a filter output of 0 dBV.

17. By sweeping the input frequency, determine the −3 dB frequencies for \(R_t\) at both extremes. Record these values in Table 22.7.6.

18. Determine the attenuation slope by measuring the output signal amplitude using a frequency one decade above the −3 dB frequency. Record this in Table 22.7.6.

19. If a spectrum analyzer is available, verify your readings.