To be able to read schematics you must know the schematic symbols. But you don’t need to memorize them all. To start with, it’s usually enough to know the battery, resistor, capacitor, transistor, diode, LED, and switch.
Later when you come across symbols you don’t know, you can come back here to identify what it is.
Below is an overview of the most used symbols in circuit diagrams.
Battery
The symbol for a battery is shown below.
A large and a small line is suppose to represent one battery cell so that the image below would suggest a two-cell battery of 3 V. But usually people just draw the battery symbol with one or two cells no matter what voltage it is.
Capacitor
Capacitors are either polarized or not. The symbols that are commonly used for the two are shown below.
A polarized capacitor is marked with a “+” sign. It is important to distinguish between these two because the polarized capacitor needs to be placed correctly according to the “+” sign.
Resistor
The schematic symbol of the resistor are drawn in two different ways. The american style resistor is drawn as a zigzag resistor while the european style resistor is drawn as a rectangular resistor.
Even though I’m from Europe, I like to draw the zigzag version. I think it is easier to draw and looks better.
Potentiometer
The potentiometer is drawn in several different ways. The symbol is usually drawn as a resistor with an arrow across it or pointing down on it as the one below.
Diode
The diode family has several different symbols because there are several different types of diodes. Below is a standard diode, a Zener diode, a Schottky diode, and a Light-Emitting Diode (LED).
Schematic Symbols of a Transistor
The most common transistor types are the Bipolar Junction Transistor (BJT), Darlington Transistor, and the Field Effect Transistor (FET). The schematic symbols for these types are shown below:
Integrated Circuit
An Integrated Circuit (IC) is usually shown as a rectangular box with pins. Below, an example of the CMOS IC 4017 is shown.
Logic Gates
Here are the schematic symbols for the logic gates:
Inductor
The inductor symbol looks like a coiled wire as this is what an inductor essentially is.
Transformer
The symbol of the transformer looks like two inductors with something in between them. Thats’s because that’s basically what a transformer is.
Switch
A switch can be represented in numerous ways in a circuit diagram. Below is a few examples:
Operational Amplifier
The operational amplifier or “opamp” is represented as a triangle with two inputs and one output. In some cases, the power supply pins are removed, but you still need to connect them for it to work.
Power symbols
In larger circuit diagrams, you usually have a lot of connections to the power supply. To simplify, it’s common to use power symbols for ground and VDD (or VCC) as shown below.
In circuits where you have a dual supply, that is positive, neutral, and negative – you usually have a third power symbol that looks like the VDD symbol, just upside down.
Photoresistor
The symbol for a photoresistor – or Light-Dependent Resistor (LDR) – looks like a resistor in a circle with arrows pointing inwards.
Crystal
The crystal is a component used to create a stable clock frequency, often for microcontrollers. In circuit diagrams it looks like this:
Fuse
Fuses are often used in higher-voltage circuits. The fuse symbol looks like this:
Fredo says
It would be nice to also include the european version of the logic gates.
Also I prefer the european version of the resistor since a sloppy drawn zigzag might also be a coil.
admin says
Good point. I’ve always found the european version of the resistor a bit boring. But I see your point about a sloppy drawn zigzag-resistor.
Oyvind
Hank says
Yes that is a good point. I’m always critical of fine points like that, that a lot of people don’t think of.
But I’m an OLD guy now (been around for a long time), and I’ve used the zigzag resister symbol all my life. My response then is if it’s sloppy and can look like a coil (which is true), just don’t be sloppy!
Another thing: The European style symbol can look like an object on a computer flowchart, many of which I have also made. So I’m not crazy about it’s boxy look because I’m used to that being on flowcharts.
Derrell says
I don’t know what a logic gate is. Could you help me?
admin says
Yes, check out this article:
https://www.build-electronic-circuits.com/logic-gates/
kingsleydara says
im a beginner in electronics, pls i nid hlp in reading intergrated circuits, its uses ,nd major function of a electrolyte capacitor
admin says
Check out this page: https://www.build-electronic-circuits.com/basic-electronic-components/
Oyvind
opolot david says
thanks nice course for me Ilove thise help me brother.
Sam says
you realy should put a PCB on this as i need it and others might to
admin says
Not sure what you mean… A PCB does not have a symbol.
Oyvnd
David Hetherington says
a PCB is the board, but some of the capacitors have difference marking for the cap. positive.
chloe says
this is useless
Sensis says
What’s the usefulness of this comment?
It’s basic electronics for people that don’t know it.
If you’re so good, create your own website, and please, do it for the pros…
And please do forget co the link.
Bless! S.
Sensis says
*And please do forget to share the link.
ifeanyi job says
wonderful. Thanks alot
Malachy says
Please i want to learn more about electronics component and fuctions
admin says
Maybe this could help: https://www.build-electronic-circuits.com/basic-electronic-components
Best,
Oyvind
chris mularn says
thanks guys this is great! i have just learnt so many things and understound basic electronics.thanks
admin says
Great!
Damilare says
God bless the developer of this site and the above writer-up . I have really gained a lot today. But , I will appreciate if u can write up how to configure the pins in an integrated circuit as well as what each term stands for? God bless you….
admin says
Hi,
Maybe this could help:
https://www.build-electronic-circuits.com/integrated-circuit/
Best,
Oyvind
Bayareddy says
Name of happy love ♥️💙♥️💙❤️ really are the best
Angel says
Hello i have a question
Liran says
Thank you very much Oyvind :-)
Can you please explain how to reverse engineer a schematic from a circuit board?
Nadeem says
Very good tutorial, we learned lot , thanks
Nadeem says
Thanks dear, tutorial is very good and simple to learn
Amir says
Please help. I’m new in this world…
On schematic, resistor with % mark instead of resistance?
What iz mean?
Thanks
admin says
That’s the precision of the resistor. 5% means the actual value is within +/- 5% of the marked value.
g says
default
Margaret says
Thank you for your tutorials! Is it possible to have a printable link for some of your pages, like this one? Thanks!
admin says
Hi,
I don’t have any way of offering that at the moment, but you could try just the print option of your browser.
Best,
Oyvind
Friday Matthew says
Please list the parts and their functions
admin says
https://www.build-electronic-circuits.com/basic-electronic-components/