The parts that switch and amplify.

Active components use a small signal to control a bigger one. That single trick is what lets circuits amplify and compute.

1. 1Semiconductors & dopingWhy silicon sits between conductor and insulator, what N-type and P-type doping do, and how a PN junction becomes the basis of every active part.1 min read·2 questions
2. 2Transistors: BJTs & MOSFETsBJTs are current-controlled, MOSFETs are voltage-controlled. Switching versus linear operation, gate drive, and choosing between them on a real design.1 min read·3 questions
3. 3Op-amps & voltage regulatorsOp-amps amplify a difference and follow feedback; regulators hold a rail steady. The golden rules, common topologies, and where each one breaks down.2 min read·2 questions
4. 4ICs & microcontrollersWhat an integrated circuit packs onto one die, how microcontrollers differ from microprocessors, and how to read a datasheet before committing to a part.1 min read·2 questions