# [Easy Explanation] How to Convert 4 to 20MA to 0 to 5V

You need a resistor to convert 4 to 20mA current to voltage. Through the equation, V=IR, calculate the value of the resistor and place that resistor in the path of the current.

You can also use a current-to-voltage converter (op-amp-based) to convert 4 to 20 mA to 5V. Now let’s get to know more about the process.

## What Resistor Converts From 4-20MA to 0-5V

Ohm’s law states:

**R = V/I **

V is the voltage, I is the current, and R is the resistance.

**R = 5V/0.020A = 25Ω**

When 20 mA flows through a 25 Ω resistor, it will drop 5 volts.

When 4 mA flows through a 25 Ω resistor, it will drop 0.1 volts. Therefore, 4-20 mA through a 25 Ω resistor will drop 0 to 5 volts.

## Current to Voltage Converter

Electronic devices that convert current signal inputs to proportional voltage outputs are known as current-to-voltage converters. They consist of an operational amplifier for simple linear signal processing and a resistor for current dissipation. The op-amp, however, is not displayed in the following circuit diagram for simplicity.

**Figure 1: Current to Voltage Converter**

Variable current is converted into equivalent output voltage by an I to V converter. We can convert our current signal of 4-20 mA to a voltage signal of 0-5 V easily using such converters. But mainly, this circuit comes in handy when the measuring equipment can only detect voltages and not currents and we want to measure the output current.

## Frequently Asked Questions

### What Is the Purpose of Converting 4-20MA to 0-5V?

The outputs of 4-20mA transducers must be transformed to signal voltages appropriate for measurement by an A/D converter in conventional process-monitoring equipment. Four milliamps in the loop are typically calibrated as zero for the monitored quantity, producing 0V at the ADC input.

### How Does the Conversion Circuit Work?

Ohm’s law states that voltage equals current times resistance, and an ordinary resistor can be used as a current-to-voltage converter. If you connect a resistor to a current source, the resistor will generate a voltage equal to the current multiplied by the “gain,” which is the resistance.

### Are There Any Considerations for Selecting Resistors?

Three steps are required for resistor selection:

- Determine the resistor’s resistance and the watts it will dissipate.
- Determine the appropriate “Watt Size” (physical size) based on watts, volts, allowable temperatures, mounting conditions, and circuit parameters.
- Select the most appropriate unit, including type, connectors, and mounting.

## Conclusion

The 4-20 mA signal is favored over the 0-20 mA signal because it can quickly identify broken wires. If the current observed in a 4-20 mA transmitter is zero, the transmitter will generate an error signal. The current signal can be relayed without error across a 1000-meter distance.

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