Electronic components, symbols and schematics
How do we draw electronic circuits?
Electronic components
The basic parts that all electronic devices are built from are called electronic components.
- Resistor – slows down or limits the flow of current.
- Capacitor – stores electrical energy for a short time.
- Diode – lets current flow in one direction only.
- Transistor – works as a switch or a signal amplifier.
- Light bulb, LED, speaker – turn electrical energy into light or sound.
Electronic symbols
Instead of drawing what a component really looks like every time, electronics uses symbols – small, simple drawings that stand for a particular component.
- A resistor is drawn as a straight line with a rectangle (or as a zigzag line).
- A capacitor as two parallel lines.
- A diode as a triangle with a line.
A table of some electronic symbols is at the end of this article.
Circuit schematics
Drawings (plans) that show how electronic components are connected are called schematics.
A schematic is like a map: it shows where each wire goes, which parts are connected, and how current flows through the circuit.
For example, in a schematic for a battery and an LED (Light Emitting Diode) you will see the battery symbol, the switch symbol, the resistor symbol and the LED symbol.
Table of common electronic symbols
| Symbol | Name |
|---|---|
 | Resistor |
 | Variable resistor |
 | Photoresistor (LDR) |
 | Thermistor |
 | Capacitor |
 | Polarised capacitor (electrolytic or tantalum) |
 | Variable capacitor |
 | Inductor |
 | Variable inductor |
 | Diode |
 | LED |
 | Photodiode |
 | Zener diode |
 | Transistor |
 | MOSFET transistor |
 | JFET transistor |
 | Operational amplifier |
 | DC voltage source |
 | Battery |
 | AC voltage source |
 | Signal generator |
 | Ground (0 V), earth |
 | Voltage regulator |
 | Push button |
 | Hall sensor (magnetic switch) |
 | Relay |
 | Switch |
 | Connected wires |
 | Wires not connected |
 | Ammeter |
 | Voltmeter |
 | Oscilloscope |
 | Antenna |
 | Crystal |
 | Integrated circuit, microcontroller |
 | Light bulb |
 | Microphone |
 | Motor |
 | Speaker |
 | Transformer |
 | Logic AND |
 | Logic NAND |
 | Logic NOR |
 | Logic NOT |
 | Logic OR |
 | Logic XNOR |
 | Logic XOR |
