Electronics 1 — Filters & Op-Amps
Decibels, RC filters with the rolloff plotted live, op-amp gain you can dial, and sizing an LED resistor.
Electricity 1 and 2 moved power. Electronics moves signals — small voltages that mean something — and the game becomes shaping them: amplify this, filter that, protect the other. Three workhorses below.
- 01 Decibels — the language of gain Signal chains multiply gains; engineers prefer adding. dB = 20·log₁₀(V_out/V_in) turns multiplication into addition: +6 dB ≈ ×2, −3 dB ≈ ×0.707 (the famous…
- 02 The RC low-pass filter One resistor, one capacitor — the simplest useful circuit in electronics. Low frequencies pass; highs are shorted away by the cap. The boundary is the cutoff:…
- 03 The op-amp — gain you choose with two resistors An op-amp has absurd gain (~100,000) and is useless raw. Feedback tames it: the amp does whatever it must to keep its inputs equal, and two resistors then set…
- 04 Sizing a real part: the LED resistor Every LED needs a resistor or it dies — the resistor absorbs the difference between supply and the LED's fixed ~2 V drop, at a current you choose:
next course: AC Motors →