circuits
4 free lessons tagged circuits across AI, Science. Each one is a short sequence of focused steps with narration and a five-question quiz at the end — take them in any order, no signup required.
Circuits: Reverse-Engineering Transformer Algorithms
How attention heads read and write to a shared residual stream, how they compose into circuits, and the two best-understood examples: the induction head behind in-context learning and the indirect object identification circuit in GPT-2.
Entanglement, gates, and the circuit model
What entanglement is mathematically, how Bell states are built from Hadamard and CNOT, how quantum circuits compose, and why measurement on entangled subsystems looks correlated regardless of separation.
Transistors: BJTs and MOSFETs
The two transistor families that built modern electronics. BJTs as current-controlled amplifiers, MOSFETs as voltage-controlled switches with a capacitor for a gate, the three operating regions of each, and the four reasons MOSFETs ended up running every digital chip.
Diodes: the simplest semiconductor device
From a single PN junction to the four-diode bridge in every wall adapter. The IV curve, rectification, Zener voltage references, fast Schottky diodes for switching supplies, LEDs and photodiodes turning current to light and back, and the five failure modes that bite real designs.