Voltage Guild
Learn electronics by building it
Read a short lesson, build the circuit, and find out precisely why it does or does not work — with real computed voltages and currents rather than a checkmark.
No account needed for First Circuits, or open the sandbox and build anything.
LED current 6.41 mA
This is the real solver, the one that grades every lesson. The dots are the current; watch them slow as the LED dims.
How it works
Three steps, every lesson
- 1
Read a short lesson
One idea at a time, in plain words, with the arithmetic worked where you can follow it.
- 2
Build the circuit
Place parts on a schematic and wire them. Voltages and currents appear as you go, and the wires show where the current flows.
- 3
Find out why
Submit it and a real solver grades what you built. Pass and you earn XP and keep your streak; miss and it says what the circuit actually did.
The courses
125 lessons across 9 courses
From a first closed loop to a transistor switch, each course opening the next.
- 1
First Circuits
What makes a circuit work: loops, voltage, current, polarity and ground — and the three faults that account for most of what goes wrong.
13 lessons · open to guests
- 2
Ohm's Law and Resistance
One relationship between voltage, current and resistance, used in all three directions — then series, parallel, and the real resistors you can actually buy.
15 lessons
- 3
Dividers & Networks
The voltage divider, what happens when you connect something to it, and the laws that explain both.
14 lessons
- 4
Measurement & Troubleshooting
Use a meter properly: what each setting connects to, what a reading is between, and how to find a fault instead of guessing at it.
14 lessons
- 5
Power, Limits & Real Components
Work out how much heat a part is producing, measure it rather than guess at it, and choose components that can survive it.
12 lessons
- 6
Diodes & LEDs
Why a diode is not a resistor, how to size the resistor that keeps an LED alive, and what a part that only conducts one way is good for.
15 lessons
- 7
Switches & Control
Wiring switches in series and parallel, reading the logic that results, and the pull-up resistor that stops an input floating.
12 lessons
- 8
Capacitors & Time
A part that takes time to change, the one number that says how long, and circuits that do something at a moment you chose.
15 lessons
- 9
Transistors
A switch closed by a signal rather than a finger. What the base current buys, how to size the resistor that supplies it, and how to drive a load nothing else in this curriculum could.
15 lessons
The Workshop
Then take it to a breadboard
A simulator can only take you so far. Build sheets unlock as you finish lessons, and each one asks you to predict a reading, wire the thing up for real, and enter what your meter actually says.
Your prediction is measured against your own supply, because a “9 V” battery rarely is.
Free while we test
Everything here is free right now
Voltage Guild is in testing, and every course is free while it is. No card, no trial clock.
Try the first course with no account at all, and add an email when you want to keep your progress.