Real circuits, ready to build
Every board from our videos, laid out on perfboard with its parts list, its cut list and a free build sheet you can follow at the bench.
46 builds
VideoThe Stranger Things light wall, from two chips
Six coloured LEDs light one at a time in a loop, like the Christmas light wall in Stranger Things. A 555 timer and a counter.
13 parts · 28 wires
LightsTimers and logic
VideoThe whole weather station is three parts
A XIAO ESP32C3 reads a temperature and humidity sensor and shows the reading as a colour on an RGB LED.
9 parts · 14 wires
Sensors
VideoIs that pin high or low? Two transistors tell you
Touch the probe to a 5V logic signal: red means high, green means low, nothing means it's floating. Two transistors, no chip.
10 parts · 6 wires
Tools and test
VideoHow your ESP32 reads a 12V battery: the voltage divider
Two resistors scale a 12V battery down to a voltage an ESP32's 3.3V input can read safely, with a zener as a backstop.
6 parts · 9 wires
PowerSensors
VideoA game show buzzer that knows who pressed first
Two players, two buttons: whoever presses first lights their LED and locks the other out. One flip-flop chip, no code.
13 parts · 25 wires
Games and toysTimers and logic
VideoA traffic light that counts to five
Red, yellow and green LEDs that cycle like a traffic light on their own. A 555 timer, a decade counter and four diodes.
15 parts · 27 wires
LightsTimers and logic
VideoThe Clapper, recreated: lights that turn on when you clap
Clap once and an LED turns on, clap again and it turns off. A microphone, two transistors and one flip-flop chip.
14 parts · 24 wires
SensorsLights
VideoThe fuzz pedal Jimi Hendrix played
A recreation of the Fuzz Face, the two transistor fuzz pedal Jimi Hendrix played, with fuzz and volume knobs.
14 parts · 18 wires
Guitar and audio
VideoThis LED tells you how dead your battery is
A light for a 12V lead acid battery: green when it's healthy, yellow when it's getting low, red when it's nearly flat.
13 parts · 17 wires
PowerTools and test
VideoA laser tripwire alarm, like in the movies
Break the laser beam and a red LED and buzzer latch on until you press reset. A photoresistor and one 555 timer.
14 parts · 22 wires
SensorsGames and toys
VideoThis lights an LED from a dead battery
One transistor and a hand wound coil that light a white LED from a nearly dead 1V cell. Six parts.
6 parts · 9 wires
LightsPower
VideoThe most famous chip in electronics
The 555 timer doing its classic job: blinking an LED about once a second. A good first build.
9 parts · 14 wires
Timers and logicLights
VideoThe amplifier inside a million kit speakers
The LM386 minimum parts amplifier, the chip inside countless kit speakers, with a volume knob and a terminal for a small speaker.
10 parts · 17 wires
Guitar and audio
VideoA roulette wheel that spins and slows to a stop
Press the button and a ring of ten LEDs spins, slows down and stops on one. A 555 timer, a decade counter and one capacitor.
20 parts · 40 wires
Games and toysLights
VideoIt tells me how full the tank is
Three LEDs stacked like the tank they watch: each one lights when the water reaches its probe. Three transistors, no chip.
14 parts · 13 wires
Sensors
VideoEvery LED needs this resistor. Here's the math
Three red LEDs on 5V, each behind a different resistor, so you can see how the resistor value sets the brightness.
7 parts · 9 wires
Lights
VideoThe two-knob synth from 1980 still sounds like a broken robot
A two knob noise box from a pair of 555 timers. It makes the stepped, gritty square wave tone people have built since 1980.
11 parts · 17 wires
Guitar and audioGames and toys
VideoThe circuit inside every guitar pedal
A one transistor clean boost that makes a guitar about twenty times louder, with a volume knob. The core of most pedals.
11 parts · 11 wires
Guitar and audio
VideoAn H-bridge with no chip
Four transistors and four diodes that drive a DC motor either way from two control inputs. No driver chip.
12 parts · 16 wires
Power
VideoWhy the most-built circuit gets hot (the math)
A 7805 taking 12V down to 5V, and the one line of math that tells you whether it needs a heatsink.
8 parts · 10 wires
Power
VideoKITT's scanner from two chips
The sweeping eye from KITT in Knight Rider, from a 555 timer, a decade counter and two steering diodes.
12 parts · 25 wires
LightsTimers and logic
VideoI replaced three chips with one
The chaos lamp again, but one CD4093B chip replaces three 555s, blinking an RGB LED's colours at rates that never line up.
12 parts · 21 wires
LightsTimers and logic
VideoOne knob dims a 12V LED strip. No code.
One knob dims a 12V LED strip. A 555 timer makes the PWM and a MOSFET switches the strip. No microcontroller, no code.
12 parts · 22 wires
LightsPower
VideoThree chips, three clocks, a color that never repeats
Three 555 timers blink the red, green and blue of one LED at unrelated rates, so the colour drifts for ages before it repeats.
12 parts · 27 wires
LightsTimers and logic
VideoThe most-built circuit in electronics
A 7805 regulator board: 7 to 12 volts in from a barrel jack, a steady 5 volts out, and an LED that shows it's on.
10 parts · 7 wires
Power
VideoI built the siren for my police light
A wailing police siren from two 555 timers: a slow one sweeps the pitch of a fast one up and down into a small speaker.
12 parts · 24 wires
Guitar and audioGames and toys
Premieres Oct 8A lie detector from two transistors
A skin resistance meter: a green LED fades and a red one comes up as your fingers sweat. It reads sweat, not lies.
12 parts · 15 wires
SensorsGames and toys
Premieres Oct 11A lamp you turn on by touching it
Tap a metal pad and two white LEDs turn on, tap again and they turn off. One flip-flop chip and a MOSFET.
13 parts · 13 wires
LightsSensors
Premieres Oct 13This LED turns red when the room gets hot
An RGB LED that shows the room temperature: red when it's hot, blue when it's cold, green in between. Two knobs set the limits.
13 parts · 23 wires
SensorsLights
Premieres Oct 16A Fender amp's treble, middle and bass knobs are just this
The passive tone stack behind a classic Fender amp's treble, middle and bass knobs: three pots, three caps and one resistor.
9 parts · 9 wires
Guitar and audio
Premieres Oct 18Why your car's dome light fades out slowly
Press a button and three warm white LEDs stay on, then fade out slowly, like a car's dome light. One MOSFET, no code.
10 parts · 8 wires
Lights
Premieres Oct 21A metronome you can see, and hear, from one 555
A metronome from one 555 timer: an LED flashes and a buzzer clicks on every beat, from about 36 to 206 beats a minute.
11 parts · 18 wires
Guitar and audioTimers and logic
Premieres Oct 23One part saves your board when you plug it in backwards
One P channel MOSFET that passes power with almost no loss when you plug in the right way, and blocks it when you don't.
7 parts · 7 wires
Power
Premieres Oct 26How does a night light know it's dark?
A night light that switches two LEDs on when the room goes dark. A photoresistor, a trim knob and two transistors.
11 parts · 8 wires
SensorsLights
Premieres Oct 28Jack-o'-lantern eyes that flicker, from one 555
Two orange LEDs that flutter like jack-o'-lantern eyes, one brightening as the other dims. One 555 timer.
12 parts · 18 wires
Lights
Premieres Oct 31How bright is it in here, in four LEDs
Four LEDs that light one after another as a room gets brighter. A photoresistor and one quad op amp chip, no code.
18 parts · 21 wires
SensorsTools and test
Premieres Nov 2A railroad crossing light, from two transistors
Two red LEDs that take turns flashing like a railroad crossing signal, about fifty times a minute. Two transistors, no chip.
11 parts · 14 wires
Lights
Premieres Nov 5Why every button needs this resistor
Why a button input needs a pull-up: a 10k resistor holds the input high until you press, and an LED shows the state.
9 parts · 12 wires
Timers and logic
Premieres Nov 7Remember the MacBook breathing sleep light?
The slow breathing sleep light from older MacBooks, recreated with one 555 timer and two transistors. About twelve breaths a minute.
11 parts · 19 wires
Lights
Premieres Nov 10The tool every electronics bench has, from one chip
Touch two probes across anything that conducts and it beeps. A bench continuity tester from one 555 timer and a piezo.
10 parts · 14 wires
Tools and test
Premieres Nov 12The circuit inside every relay module
The small circuit inside every hobby relay module: a transistor switch, a base resistor, a flyback diode and a status LED.
7 parts · 9 wires
Power
Premieres Nov 15Dice that roll themselves, from two chips
Hold the button and a seven LED die face flickers through faces. Let go and it stops on one. A 555, a counter and six diodes.
25 parts · 36 wires
Games and toysTimers and logic
Premieres Nov 17One resistor and one capacitor set every timer in electronics
Press a button and an LED stays lit for about 1.1 seconds, set by one resistor and one capacitor. Swap the resistor to change it.
9 parts · 15 wires
Timers and logic
Premieres Nov 22The regulator every ESP32 secretly needs
A 3.3V supply for an ESP32: an LD1117 regulator with enough capacitance to ride out the radio's current spikes, plus a power LED.
8 parts · 12 wires
Power
Premieres Nov 25The emergency light that turns on when the power dies
Three white LEDs that switch on from a battery the moment the wall adapter loses power, and charge it while it's plugged in.
14 parts · 5 wires
LightsPower
Premieres Nov 27The clock every computer runs on, slow enough to see
A 555 timer ticking about once a second, one LED on the high half and one on the low half. A computer clock you can watch.
11 parts · 17 wires
Timers and logicLights
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