op-amps
an operational amplifier is a high-gain differential amplifier. with feedback it becomes a friendly building block.
what can they do?
- buffer a signal (voltage follower).
- amplify: non-inverting (gain = 1 + R2/R1) or inverting (gain = −R2/R1).
- filter, mix, compare.
pick “rail-to-rail” input/output for 3.3 V work; decouple the op-amp just like any IC.
fact
a follower gives high input impedance and low output impedance; great between a sensor and an ADC. non-inverting gain
Gain = 1 + Rf/Rg. pick R’s in the 1–100 kΩ range.