Electronic symbol

Common electronic symbols

Symbols shown are typical examples, not a complete list.

Traces

Grounds

The shorthand for ground is GND. Optionally, the triangle in the middle symbol may be filled in.

Resistors

It is very common for potentiometer and rheostat symbols to be used for many types of variable resistors and trimmers.

Capacitors

Diodes

Optionally, the triangle in these symbols may be filled in, or a line may be drawn through the triangle (less desirable). The words anode and cathode are not part of the diode symbols. For instructional purposes, sometimes one or two letters (A/C or A/K) are placed next to diode symbols similar to how the letters C/B/E or D/G/S are placed next to transistor symbols. "K" is often used instead of "C", because the origin of the word cathode is kathodos, and to avoid confusion with "C" for capacitors in silkscreen of printed circuit boards. Voltage text should be placed next to each zener and TVS diode symbol too, such as "5.1V".

Bridge rectifiers

There are many ways to draw a single-phase bridge rectifier symbol. Some simplified symbols do not show the internal diodes.

Inductors

An inductor can be drawn either as a series of loops, or series of half-circles.

Transformers

Voltage text should be placed on both sides of power transformers, such as 120V (input side) and 6.3V (output side).

Transistors

Optionally, transistor symbols may include a circle. Note: The pin letters B/C/E and G/D/S are not part of the transistor symbols.

Bipolar

Unipolar

Vacuum tubes

Switches

For multiple pole switches, a dotted or dashed line can be included to indicate two or more switch at the same time (see DPST and DPDT examples below).

Relays

Relays symbols are a combination of an inductor symbol and switch symbol.

Note: The pin letters in these symbols are not part of the standard relay symbol.

Lamps

LED is located in the diode section.

Current limiters

Voltage limiters

TVS and Zener diodes are located in the diode section.

Electro-acoustic devices

Speaker symbols sometimes include an internal inductor symbol. Impedance text should be placed next to each speaker symbol, such as "8 ohms".

Antennas

Cables

Connectors

There are numerous connector symbol variations.

ICs

Logic gates

For the symbols below: A and B are inputs, Q is output. Note: These letters are not part of the symbols.

There are variations of these logic gate symbols. Depending on the IC, the two-input gates below may have: 1) two or more inputs; 2) infrequently some have a second inverted Q output too.

The above logic symbols may have additional I/O variations too: 1) schmitt trigger inputs, 2) tri-state outputs, 3) open-collector or open-drain outputs (not shown).

Flip-flops

For the symbols below: Q is output, Q is inverted output, E is enable input, internal triangle shape is clock input, S is Set, R is Reset (some datasheets use clear (CLR) instead of reset along the bottom).

There are variations of these flip-flop symbols. Depending on the IC, a flip-flop may have: 1) one or both outputs (Q only, Q only, both Q & Q); 2) one or both forced inputs along top & bottom (R only, S only, both R & S); 3) some inputs may be inverted.

OpAmps

Note: The outside text is not part of these symbols.

Voltage Regulator

Note: 3pin linear or LDO voltage regulator symbols typically have three words inside their symbols, such as "In" on left side, "Out" on right side", "Gnd" on bottom (for fixed output parts, such as LM7805) or "Adj" on bottom (for adjustable output parts, such as LM317).

Oscillators

Frequency text should be placed next to each oscillator symbol, such as "16MHz".

Miscellaneous devices

Historical electronic symbols

The shape of some electronic symbols have changed over time. The following historical electronic symbols can be found in old electronic books / magazines / schematics, and now considered obsolete.

Capacitors (historical)

All of the following are obsolete capacitor symbols.