Electronics 1 — Filters & Op-Amps

The op-amp — gain you choose with two resistors

continues from lesson 2 — values defined earlier in the course stay live here

ELI5: an op-amp has absurd raw gain (~100,000) and is useless on its own. Feedback tames it: the amp adjusts its output to keep its two inputs equal, and then two resistors set the gain exactly:

non-inverting: G = 1 + R₂/R₁
inverting: G = −R₂/R₁.

R_{1g} := 1000 ohm

= 1000 ohm feedback divider, bottom

R_{2g} := 9000 ohm

= 9000 ohm feedback divider, top

G_{ni} = 1 + \frac{R_{2g}}{R_{1g}}

10

non-inverting gain: exactly ×10

V_{in} := 0.2 V

= 0.2 V a sensor signal

V_{out} = G_{ni} \cdot V_{in}

= 2 V amplified to 2 V — ADC territory

✓ pass

V_{out} < 5 V

stays inside a 5 V supply — no clipping

Real-world hook: op-amps amplify the microvolts from a microphone, the millivolts of an ECG, and the output of nearly every sensor before a chip can read it.