What we learn and make, session by session
Nine sessions, one evening each. Every session teaches one idea and ends with something that lights up or makes sound. Read the card before you start a session; the buttons take you to its build steps, simulator, workbench level and book chapter.
Nine evenings from a battery to a boxed synth
Each session is one evening of 2–3 hours and ends with something that makes sound. Concept first, then build on the breadboard, experiment, and read the matching Book chapter afterwards.
Your status changes are saved: in your account when you're signed in, otherwise on this device.
Next level
After Session 8, pick one track; each takes a few weeks.
- Real VCO. A transistor or op-amp oscillator that follows 1V per octave, so it plays in tune. Follow Moritz Klein's breadboard VCO series, starting with DIY VCO Part 1: The analog oscillator core anyone can build.
- Your own PCB. Redraw a circuit you've built in KiCad and order boards from JLCPCB.
- Eurorack format. Move to ±12V and standard panel sizes.
- The installation. Scale the LDR drone box into the wooden panel with holes and cables.
Videos for the next level
Build along, then read
- Sessions 0–3: Nicolas Collins, Handmade Electronic Music; Look Mum No Computer's 40106 drone videos.
- Sessions 4–7: Moritz Klein's breadboard videos, with Ray Wilson's Make: Analog Synthesizers as reference.
- Session 8 on: Music From Outer Space and the Mod Wiggler forum for stripboard layouts and help.
Safety
- Batteries only. Never mains power in a circuit.
- Never plug the raw 9V signal into a DJ mixer, interface or headphones.
- Hot chip or battery: disconnect and look for a short.
- Solder in a ventilated room and wash your hands after.
Build it hole by hole, then switch it on
A virtual breadboard with the real layout: each numbered column of five holes is connected, and the long red and blue rails carry + and −. Place parts the way you will on your desk; the steps tick themselves off when the connections are right.
How the workbench works
- Pick a level above. Each one is a session from the Curriculum.
- Read the orange card. It tells you what to do now and why. The part you need is already selected in the row of buttons.
- Click the glowing holes on the board: first click puts the first leg in, second click puts the other leg in. For parts with a + side (LED, 10µF, 470µF), the first click is the + leg.
- Watch the list on the right. When the connection is right, the step gets a green tick and the card jumps to the next step.
- Made a mistake? Press Undo, or turn on Remove and click the part.
How a breadboard is wired inside: each numbered column has two groups of five holes (a–e and f–j), and each group is one metal strip. The long red and blue lines at the top and bottom are the + and − rails. Hover or tap any hole to see what's joined to it.
Tip: hover or tap a hole to see which holes are joined to it. Click a part with Remove on to take it out.
Try each build before you touch a wire
Every sim uses the same part values as its real session, so a knob here does what the pot will do on your breadboard. The sound is close, not exact: real chips drift and vary.
How the simulator works
- Each card below is one session from the Curriculum, with the same parts as knobs.
- Press Power on a card to hear it. Press it again to stop. Only one card plays at a time.
- Move the sliders. They are your pots, capacitors and light sensor; the number next to each one is its real value.
- Watch the screen under the knobs. It's an oscilloscope: it draws the sound you hear, so you can see what each knob does to the wave.
- Follow the Try this list on each card, top to bottom.
Start quiet. Square waves are harsh, just like the real thing. Only one sim plays at a time.
What to buy, and when
Place Order 1 now. Wait with Order 2 until Session 3 is done. Turkish shops such as Direnc.net or Robotistan carry all of it. Your ticks are saved as you go.
Keep this open while you build
Units and formulas
Prefixes: 1k = 1,000 · 1M = 1,000,000 · 1µF = 1,000nF · 1nF = 1,000pF. So 100nF = 0.1µF.
Ohm's law. Voltage, current and resistance.
LED resistor. Supply minus about 2V for the LED, divided by the current you want (5–10mA is plenty).
RC time. How long a capacitor takes to mostly fill. Bigger R or C means slower, which means lower pitch.
Filter cutoff. Where an RC filter starts cutting.
40106 rule of thumb: double the capacitor (or the resistor) and the pitch drops about an octave.
Reading part values
Resistors, 4 bands: first digit, second digit, number of zeros, then tolerance (gold = ±5%). Hold gold on the right. Unsure? Measure it.
| Color | Digit / zeros | Color | Digit / zeros |
|---|---|---|---|
| Black | 0 | Green | 5 |
| Brown | 1 | Blue | 6 |
| Red | 2 | Violet | 7 |
| Orange | 3 | Grey | 8 |
| Yellow | 4 | White | 9 |
The three you'll use most: brown-black-red = 1k, brown-black-orange = 10k, brown-black-yellow = 100k.
Ceramic capacitors use a 3-digit code in pF: two digits, then zeros.
| Code | Value |
|---|---|
| 102 | 1nF |
| 103 | 10nF |
| 104 | 100nF |
| 105 | 1µF |
Electrolytic capacitors print value and max voltage (10µF 25V). Pick a rating above your supply. Pots: B = linear (pitch, controls), A = logarithmic (volume). B1M = 1MΩ linear.
Which way round
| Part | Direction? | How to tell | Watch out |
|---|---|---|---|
| Resistor | No | — | Check the value first |
| Ceramic capacitor | No | — | Read the 3-digit code |
| Electrolytic capacitor | Yes | Stripe and short leg = − | Backwards can pop |
| LED | Yes | Long leg = +, flat edge = − | Always with a resistor |
| Diode | Yes | Band = the side current leaves | Backwards = no current |
| Pot | Partly | Middle leg = wiper | Swap outer legs to reverse the knob |
| LDR | No | — | Darker = more resistance |
| Chip (IC) | Yes | Notch or dot = pin 1 side | Power off before moving it |
| Transistor | Yes | Flat face to you, legs down: E B C | 2N3904 and 2N3906 look alike |
Chip pinouts
Notch at the top: pin 1 is top-left; count down the left side, then up the right.
CD40106 · six oscillators · 14 pins
| Inverter | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| Input pin | 1 | 3 | 5 | 9 | 11 | 13 |
| Output pin | 2 | 4 | 6 | 8 | 10 | 12 |
Pin 14 = +, pin 7 = ground. Unused inputs go to ground.
TL072 · two op-amps · 8 pins
| Pin | Job | Pin | Job |
|---|---|---|---|
| 1 | Output A | 8 | +V |
| 2 | − input A | 7 | Output B |
| 3 | + input A | 6 | − input B |
| 4 | −V | 5 | + input B |
CD4017 · step counter · 16 pins
| Step | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Pin | 3 | 2 | 4 | 7 | 10 | 1 | 5 | 6 | 9 | 11 |
Pin 16 = +, pin 8 = ground, pin 14 = clock in, pin 13 = ground, pin 15 = reset (to ground, or to a step's pin for a shorter loop). The LM386 module is labeled VCC, GND, IN and speaker +/− on the board.
When it doesn't work
Go through these in order; most problems are the first three.
- Power: fresh battery? About 9V between the chip's + and ground pins?
- Rails: are the breadboard's power rails connected? Some split in the middle.
- Chip direction: notch in the right place, straddling the center gap?
- Rows: is each leg in the row you think? One hole off is the classic mistake.
- Ground: does everything, amp module included, share ground?
- Unused inputs on the 40106 grounded?
- Polarity: electrolytics, LEDs and diodes the right way round?
- Values: measure resistors, read capacitor codes.
- Too slow to hear? Put an LED on the output to see it blink.
- Hot part? Disconnect power and look for a short.
Glossary
| Word | Meaning |
|---|---|
| Oscillator | A circuit that flips back and forth by itself; makes a tone |
| VCO | Voltage-controlled oscillator: pitch follows a control voltage |
| LFO | Low-frequency oscillator: too slow to hear, moves other things |
| Control voltage (CV) | A voltage that controls pitch, volume or cutoff instead of being heard |
| Filter / cutoff | Removes some frequencies; cutoff is where it starts |
| Resonance | A boost right at the cutoff; makes the filter sing |
| VCA | Voltage-controlled amplifier: volume follows a control voltage |
| Envelope | A shape over time (rise, fall) started by a gate |
| Gate / trigger | An on-off pulse that starts something |
| Clock | A steady stream of pulses that keeps time |
| Sequencer | Steps through a list of values in a loop |
| Square wave | The 40106's sound: jumps between high and low; buzzy |
| DC blocking | A capacitor that passes sound but blocks steady voltage |
| Ground | The shared 0V reference |
| Dual supply (±V) | Plus and minus voltage around ground; op-amps like it |
| Breadboard / stripboard | Temporary board without solder / permanent board with solder |
The ideas behind each build
Ten short chapters. Read one after each session.
What you built, heard and got stuck on
Two minutes after each session saves an hour later. Notes save a moment after you stop typing: to your account when you're signed in, otherwise on this device.