How to Convert Current to Voltage using Resistor ?

In this article, we discuss about How to Convert Current to Voltage using Resistor with different examples like 0-20 mA to 0-10 VDC Conversion, 4-20 mA to 2-10 VDC Conversion, 0-20 mA to 0-5 VDC Conversion.

Convert Current to Voltage

It is extremely simple to measure 0-20 mA signal with a device that will measure only Voltage inputs. If the Voltage input module available will accept a 0-10 Vdc signal, but may not accept a 0-20ma signal directly.

Basically, Ohms law is used to calculate a resistor value in order to convert the 0-20ma signal to a voltage.

Current to Voltage Conversion Circuit

Example : 0-20 mA to 0-10 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance

R = 10V/0.020A = 500 Ohms

0-20 mA to 0-10 VDC Conversion
V = I*R = 0*500 = 0V
 

V = I*R = 0.020*500 = 10V

Example : 4-20 mA to 2-10 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance 

R = 10V/0.020A = 500 Ohms

4-20 mA to 2-10 VDC Conversion
V = I*R = 0.004*500 = 2V

V = I*R = 0.020*500 = 10V

Example : 0-20 mA to 0-5 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance 

= 5V/0.020A = 250 Ohms

0-20 mA to 0-5 VDC Conversion

V = I*R = 0*250        = 0V

V = I*R = 0.020*250 = 5V

Note:-

  • To avoid damage you must ensure that the external current source has short-circuit protection in all conductor cases.
  • The external resistor is a source of error because of its dependency on temperature and its inaccuracy.
  • In order to obtain measuring results that are as precise as possible it is recommended to use resistors with tolerances that are as small as possible.

Credits : myplctechnology blog

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