Resistor symbols

Chapter 2 - Resistor standards and codes

All types of resistors have their own resistor symbols which are used when a circuit diagram is drawn. This page will explain the different standards which are used for resistor symbols and display the most common symbols.

Standards for resistor symbols

Several standards exist, which describe how the different components should be displayed. In the past a lot of countries or even industries used their own standards, which can be confusing. Nowadays the IEC 60617 standard is international standard for these electronic symbols. However the local standards are still used from time to time. In general, the ANSI standard is still common in the United States. Some examples of standards which describe resistor symbols:

  • IEC 60617 (International)
  • ANSI Y32 / IEEE 315 (US) - old
  • DIN 40900 (Germany) - old
  • AS 1102 (Australia) - old

Sometimes the symbol for a particular device is different when it is used in another field of application. Other symbols are used in electronics then for example in architecture and buildings. On top of this, many local deviations from the international standards exist. The following table shows the most common resistor symbols for electronics design.

Schematic symbols

 

 

 

 

 

Type Abbreviation IEC (International) ANSI (US)
Fixed resistor R resistor symbol resistor symbol - US
Heating resistor   heater resistor symbol  
Variable resistors VR    
Potentiometer   Potentiometer symbol

 

 

 

Potentiometer symbol US

 

 

 

Trimming potentiometer   Trimpot symbol Trimpot symbol US
Rheostat   Rheostat symbol Rheostat symbol US
Preset resistor  

 

Preset resistor symbol

 

preset symbol US
 
Dependent resistors      
Photo resistor or Light dependent resistor LDR  LDR symbol  LDR symbol US
Varistor or Voltage dependent resistor  VDR

 

RV

MOV
VDR symbol VDR symbol US
NTC thermistor NTC

 

RT
thermistor symbol thermistor symbol american
PTC thermistor PTC

 

RT
PTC thermistor symbol PTC thermistor symbol US
Magneto resistor or Magnetic dependent resistor  MDR magneto resistor symbol magneto resistor symbol US