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curriculum/Network Analysis
section 11 of 122 min read

11. Things to Try Before Moving On

  1. Build a voltage divider with two 10 kΩ resistors and a 9 V battery: 4.5 V open-circuit. Connect a 10 kΩ load and the output drops to 3 V. Compute Thevenin (VTh=4.5V_{Th} = 4.5 V, RTh=5R_{Th} = 5 kΩ) and check: 4.5×10/(5+10)=34.5 \times 10/(5+10) = 3 V.
  2. RC low-pass filter. R=10R = 10 kΩ, C=100C = 100 nF; cutoff 1/(2πRC)=1591/(2\pi RC) = 159 Hz. Sweep with a function generator and observe the -20 dB/decade rolloff.
  3. Series RLC. L=1L = 1 mH, C=100C = 100 nF, R=10R = 10 Ω. f0=16f_0 = 16 kHz. Sweep and watch the sharp peak.
  4. RC time constant. Charge a 100 µF cap through 10 kΩ from 5 V. τ=1\tau = 1 s; should hit 63% (3.15 V) at 1 s.
  5. Thevenin in SPICE. Build a small mixed-source network in LTspice or Falstad. Hand-compute Thevenin at chosen terminals. Attach a load and verify simulation matches.
  6. Dependent-source Thevenin. Build a common-emitter amplifier in SPICE; use the test-source method at the collector node and verify in simulation.
  7. Measure ringing. Connect a fast logic gate to a scope through a long jumper. Observe damped oscillation on each edge. Use f0=1/(2πLC)f_0 = 1/(2\pi\sqrt{LC}) to estimate the parasitic L and C.
  8. Bode in Python. Use the script in Section 8.6 to plot bandpass for three Q values; watch the peak sharpen.
  9. 4-mesh circuit by matrix. Hand-build the matrix, solve in numpy, compare against SPICE.
  10. Z parameters from topology. Compute Z for a textbook RC ladder, convert to ABCD, then verify in simulation.

When you can predict roughly what an RC, RLC, or Thevenin-equivalent will do without computing, you have the chapter under your belt.