electronics

A benchtop spin coater with closed-loop speed and acceleration control, built from catalogue parts for about ₹3,000.

Arduino · Embedded C · PID control · Gain scheduling

A transformer-less, direct-coupled linear amplifier that drives magnetic cores from 50 Hz to 250 kHz, so their B–H loops can be measured across four decades of frequency.

Analogue design · KiCad · Proteus · MATLAB

A 16-bit pipelined CPU in VHDL: eight registers, three instruction formats, six stages, and the forwarding and interlock logic needed to keep them fed.

VHDL · Digital design · Computer architecture

Two ultrasonic sensors in a doorway, an Arduino working out which way you walked, and a NodeMCU putting the room’s occupancy on the internet.

Arduino · NodeMCU · HC-SR04 · Adafruit IO

A differential-drive racing bot driven from a phone, on a motor driver board I laid out myself because the ready-made one was the wrong shape.

ATTINY2313A · L293D · Eagle · Bluetooth

A hub motor, a controller and a panel on a bicycle — and two small ideas about when the motor should be allowed to help. Built at thirteen.