The brief
Purdue’s Introduction to Electronics Milestone workshop takes you through the full loop that turns a circuit idea into a working board: build it on a breadboard, capture the schematic, lay out a PCB, and hand-solder the surface-mount parts onto it. Two circuits carried the course — a blinker and a light-in-the-dark — each built twice, first as a breadboard prototype and then as a soldered board.
The value isn’t either circuit on its own. It’s doing every stage yourself, so a schematic stops being a drawing and becomes a thing you can route, fabricate, and debug when it doesn’t light up the first time.
Blinky: breadboard first
The first circuit is an op-amp relaxation oscillator that blinks an LED. Before committing anything to copper, it went up on a breadboard — a dual op-amp, the RC network that sets the blink rate, and the LED — and was probed with a multimeter to confirm it actually oscillated.
Breadboarding first is the cheap place to be wrong. A jumper in the wrong row costs seconds to move; the same mistake etched into a board costs a rework.
GoodNightLight: sensing the dark
The second circuit adds a sensor. A photocell and a fixed resistor form a voltage divider whose midpoint tracks ambient light; an op-amp comparator watches that midpoint against a reference and switches the LED on when the room goes dark — a night light with no switch.
Then the soldering: surface-mount resistors, the op-amp, the photocell, and a through-hole LED, all placed and reflowed by hand onto the fabricated board and powered from a 9 V battery.
What it taught
The pair of circuits covers the whole electronics fundamentals loop: op-amp behaviour on a breadboard, schematic capture, PCB layout and routing, and surface-mount hand soldering — and, underneath all of it, the habit of proving a circuit works cheaply before spending a board on it. It’s the hands-on complement to the analog theory: the point where a comparator stops being a triangle on a page and becomes a light that comes on in the dark.
