This notation is designed to be relatively easy to write. This is achieved by not drawing ultra complex ASCII art boxes of every component. It would be slightly more readable if we did that, but prioritizing the writer here.
Two wires are only joined if + is given. E.g. the following two wires are not joined:
  |
--|--
  |
but the following are:
  |
--+--
  |
Simple symmetric components:
Asymmetric components have multiple letters indicating different ports. The capital letter indicates the device, and lower case letters the ports. The wires then go into the ports:
  • D: diode
    • a: anode (where electrons can come in from)
    • c: cathode
    Sample usage in a circuit:
    --aDc--
    Can also be used vertically like aany other circuit:
    |
    a
    D
    c
    |
    We can also change the port order, the device is still the same due to capital D:
    --cDa--
    
     |
    Dac--
    
     |
    Dca--
    
       |
    --caD
  • DC DC source. Ports:
    • p: positive
    • n: negative
    E.g. a 10 V source with a 10 Ohm resistor would be:
    +---pDC_10_n---+
    |              |
    +----R_10------+
    If only one side is given, the other is assumed to be at a the ground G. We can also omit p and m in that case and assume that p is the one used, e.g. the above would be equivalent to:
    DC_10---R_10---G
    If the voltage is not given, it is assumed to be a variable voltage power supply.
  • LED: same as diode
  • I: electric current source. Ports:
  • P: potentiometer source. Ports:
    • 1: one of the sides
    • 2: the middle
    • 3: the other side
  • T: transistor. The ports are sgTd:
    • s: source
    • g: gate
    • d: gate
    Sample usage in a circuit:
    ---+
       |
    --sgTd--
    All the following are also equivalent:
       |
       g
    --sTd--
    
        |
    --Tsgd--
       |
  • V: Voltmeter. Ports:
    • p: positive
    • n: negative
    If we don't need to specify explicit positive and negative sides, we can just use:
    ---V---
    without any ports. This is notably often the case for AC circuits.
    Optionally, we can also add the sides as in:
  • ports can also be separated by double underscores from the component names to increase readability. Single underscores can also be used to increase readability of longer multi-word component names e.g.:
    RPI_PICO_W__1gp0__3gnd
                |       |
                R_2k    |
                |       |
                +-aLEDc-+
    which is the same as:
    RPI_PICO_W
    1gp0  3gnd
    |       |
    R_2k    |
    |       |
    +-aLEDc-+
    represents a circuit linking port 1 of a Raspberry Pi Pico W, which is GPIO pin 0, through a resistor and an LED, back to pin 3 of the board, which is ground.
Numbers characterizing components are put just next to each component with an underscore. When there is only one parameter, standard units are assumed, e.g.:
+-----+
|     |
C_1p  R_2k
|     |
+-----+
means:
Micro is denoted as u.
Wires can just freely come in and out of specs of a component, they are then just connected to the component, e.g.:
DC_10---R_10---G
means applying a voltage of 10 V across a 10 Ohm resistor, which would lead to a current of 1 A
If a component has more than two parameters, units are used to distinguish them when possible, e.g.:
AC_1kV_2MHz
means an AC source with:
Electronic component by Ciro Santilli 40 Updated 2025-07-16
Video 1.
Open Circuits book interview by CuriousMarc (2022)
Source.
Amplifier by Ciro Santilli 40 Updated 2025-07-16
Main implementations: the same as electronic switches: vacuum tubes in the past, and transistors in the second half of the 20th century.
Video 1.
How to make an LM386 audio amplifier circuit by Afrotechmods (2017)
Source. Builds the circuit on a breadboard from minimal components, including one discrete transistor. Then plays music from phone through headset cables into a speaker.
Capacitor by Ciro Santilli 40 Updated 2025-07-16
The fundamental intuition about capacitors is that they never let electrons through.
They can only absorb electrons up to a certain point, but then the pushback becomes too strong, and current stops.
Therefore, they cannot conduct direct current long term.
For alternating current however, things are different, because in alternating current, electrons are just jiggling back and forward a little bit around a center point. So you can send alternating current power across a capacitor.
The key equation that relates Voltage to electric current in the capacitor is:
So if a voltage Heavyside step function is applied what happens is:
  • the capacitor fills up instantly with an infinite current
  • the current then stops instantly
More realistically, one may consider the behavior or the series RC circuit to see what happens without infinities when a capacitor is involved as in the step response of the series RC circuit.
Figure 1.
Electronic symbol of a capacitor
. Source.
Video 1.
Finding capacitance with an oscilloscope by Jacob Watts (2020)
Source. Good experiment.
Video 2.
Capacitors Explained by The Engineering Mindset
. Source. 2019.
This is what happens when you apply a step voltage to a series RC circuit: TODO graph.
Diode by Ciro Santilli 40 Updated 2025-07-16
Ideally can be thought of as a one-way ticket gate that only lets electrons go in one direction with zero resistance! Real devices do have imperfections however, so there is some resistance.
First they were made out of vacuum tubes, but later semiconductor diodes were invented and became much more widespread.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact