Electronic component appearance and schematics – Commonly used through hole versions

Here’s the primary appearance of the most commonly used components used in basic electronics.

Common resistor diode capacitor component appearances diagram by electronzap electronzapdotcom electronics
Common resistor diode capacitor component appearances diagram by electronzap electronzapdotcom electronics

Common physical properties:

  • Resistors: Are mostly blue these days, but beige are still out there quite a bit.  The color bands (usually 5 for blue and 4 for beige) indicate it’s rated value and tolerance, which is the percentage higher or lower it might vary from rated value.  I’ve come across some green components that look like resistors but are actually inductors.
Rectifier diode and LED schematic symbols and common appearance with forward biased polarity diagram by electronzap electronzapdotcom
Rectifier diode and LED schematic symbols and common appearance with forward biased polarity diagram by electronzap electronzapdotcom
  • Diodes: Cylindrical and have a band to indicate the cathode. They are usually black plastic with a gray band or glass with a black band. The band indicated the side of the diode that is the cathode.

They are polarized. They conduct current fairly well when anode is more positive than cathode (forward biased). Most diodes shouldn’t conduct at all when cathode is more positive than anode (reverse biased).

Avoid exceeding the breakdown voltage, which is the voltage that diodes might start conducting current at while reverse biased.

Part number: Each diode type has differing electrical properties. Different types of diodes have slightly different schematic symbols as well. It is important that you look at the part number and review it’s datasheet (do a google search to find it) of any new diode. The most basic diode is called a rectifier diode.

  • LEDs: Abbreviation for light emitting diodes. They may be clear or in plastic that is the color of the light that they emit. Being a diode, they are polarized and need to be forward biased to conduct. The anode (longer metal wire if uncut) needs to be more positive and cathode (shorter lead if Anode hasn’t been cut). Often the LED cathode also has a flat edge along the rim.
  • Capacitors: larger values are almost always a sealed can and are almost always polarized (important to apply power in the right direction to avoid destruction of them). They usually have a shorter lead (metal wire, pronounces like “leed”), plus a band running down the side with dashes, for the side that needs to be more negative. Whereas the longer lead side needs to be more positive when connected to a power supply. – Smaller value capacitors are generally disc shaped, or globular plastic, and usually not polarized. They have equal length leads and no marking for positive or negative as the can be charged in either direction.
  • Switches: I assume you can already recognize switches, so I won’t be drawing any.

Schematics:

Drawings of circuits rarely show pictures of the components. Usually there are symbols with lines drawn to show how they connect.

Most commonly seen in circuits:

Basic schematic symbols of resistor diode LED battery ground push button and toggle switch diagram by electronzap electronzapdotcom
Basic schematic symbols of resistor diode LED battery ground push button and toggle switch diagram by electronzap electronzapdotcom

Capacitors:

Polarized and non polarized capacitor schematic symbols diagram by electronzap electronzapdotcom
Polarized and non polarized capacitor schematic symbols diagram by electronzap electronzapdotcom
  • Polarize capacitor: The straight line, which may or may not have a plus symbol next to it,  is the side of the circuit that gets a more positive charge.
  • Nonpolarized capacitors can be charged in either direction, so it doesn’t matter which way you put them in a circuit.

Variations of diodes and resistors:

Common resistor and diode component variations diagram by electronzap electronzapdotcom
Common resistor and diode component variations diagram by electronzap electronzapdotcom
  • Zener: Special type of diode that can safely conduct some current while reverse biased. They come in different zener voltages much like resistors come in different values. Usually the voltage is written in small print on the component. A 5.6V zener diode for example usually has 5V6 written on it, but you will probably need a magnifying glass or loop to read it. The V for voltage takes the place of the decimal point, which you probably wouldn’t see on such as small component.
  • Schottky: Diode that conducts at a lower forward voltage than silicon based rectifier diodes.
  • Trimpot (trimmer potentiometer): Can either be used as a variable resistor or voltage divider.
  • Light dependent resistor: A resistor whose resistance changes based on how much light is falling on it.

Keep scrolling down to see more topics!

You can support my work by donating to or checking out…

Become a Patron!

Related topics:

Other basic electronics topics that you should know before moving on to more advanced topics.

Next topics:

More advanced topics for after you have the basics down.

Circuits covered more quickly series: