How to Use This Calculator
- Enter the Source Voltage of your circuit in volts (V).
- Enter the Load Resistance in ohms (Ω).
- Enter the Desired Current you want to limit the circuit to in amperes (A).
- Click the Calculate button to determine the appropriate resistor value and power rating.
- The calculator will display the recommended resistor value and the minimum power rating needed for the resistor.
Working Principle
This calculator helps determine the value of a current-limiting resistor needed in an electrical circuit. The resistor is placed in series with the load to limit the current to a desired value.
The formula used is:
R = (V_source - V_load) / I_desired
Where:
- R = Resistor Value (Ω)
- V_source = Source Voltage (V)
- V_load = Load Voltage (V_load = I_desired × R_load)
- I_desired = Desired Current (A)
Important Considerations
- The calculated resistor value is based on the assumption that the load resistance remains constant.
- The power rating of the resistor should be at least 1.5 times the calculated power dissipation to ensure safe operation.
- For high-power applications, consider using resistors with a higher power rating or multiple resistors in parallel.
- Always verify the actual current after installation to ensure it matches your requirements.