Blinky v1.1A — Two-Transistor Learning Kit

$9.95

Solder your first circuit in an evening and finally understand how a transistor works. Two LED eyes blink back and forth, all by themselves.

The best first kit you’ll ever build

Blinky is a little circuit-board face whose two LED eyes take turns blinking — left, right, left, right — for as long as the battery lasts. You’ll build it in an evening or less, and along the way you’ll learn how a transistor works, the most important idea in all of modern electronics.

It’s a classic two-transistor astable multivibrator — the same circuit the designer, Kevin (W8VOS), built in 1983 at Basic Electronics Tech school at Keesler Air Force Base. Understand Blinky and you understand the transistor as a switch.

What you’ll learn

• Soldering, properly. Step-by-step method, what a good joint looks like, and how to fix the common faults.
• Components. Resistors and colour codes, electrolytic capacitors, LEDs (anode vs. cathode), and NPN transistors and their pinouts.
• How it actually works. A short course in transistors — vacuum tubes, Bell Labs 1947, doping, PN junctions, NPN vs. PNP — then exactly why each eye stays lit for about 0.72 s (0.693 × 47 kΩ × 22 µF).
• Think like a technician. The rev A board’s LED silkscreen is printed reversed, and the manual turns that into a lesson: “Don’t trust the silkscreen: check with the schematic.” You’ll prove the correct LED direction yourself from the schematic and the copper, a habit that pays off in every kit after this one.
• Troubleshooting and experiments to go further once it blinks.

Classic-style manual: every step has a check box, so you always know where you left off.

What’s in the box

• Blinky circuit board, v1.1 rev A, 2.500 × 3.400 in (63.5 × 86.4 mm)
• 2 × 330 Ω resistors (R1, R4)
• 2 × 47K resistors (R2, R3)
• 2 × 5 mm LEDs, matched pair (D1, D2). LED colour may vary.
• 2 × 22 µF electrolytic capacitors (C1, C2)
• 2 × small-signal NPN transistors, matched pair (BC548, 2N3904, PN2222 or similar)
• 9 V battery snap

9 V battery not included. LED colour may vary. There’s no power switch — unsnap the battery to turn it off.

At a glance

What you’ll need

Soldering iron (25–40 W, or a station at ~650–700 °F), rosin-core solder, iron stand and tip cleaner, diagonal cutters, long-nose pliers, a multimeter (for the LED check and experiments), safety glasses, and good light. Desoldering braid is handy.

Manuals

• Blinky v1.1 rev A Assembly Manual (PDF)

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