Resonant filter — Bode plot
4 parts
The first circuit built for the AC SWEEP rather than the scope. A series R–L–C driving its capacitor is a second-order low-pass with Q ≈ 3.2: flat at 0 dB through the audio band, a +10 dB resonant peak at 5 kHz, then a −40 dB/decade dive that reaches −92 dB by 1 MHz. The source's 1 V amplitude is also its AC magnitude, so the output trace reads gain in dB directly and the input probe draws the flat 0 dB reference line.
- V1 1V·5kHz
- R1 100Ω
- L1 10mH
- C1 100nF
