Resistor Scientific Calculator

The resistor RL is the load resistor, R is the voltage regulator adjustment resistor (also called the current limiting resistor), and D is the voltage regulator tube. According to the design principle of the voltage regulator circuit, when the input voltage is basically unchanged, the RL becomes small and flows through the RL. The current increases, but the current through D decreases.
purpose
Reducing the load current, such as adding a current limiting resistor at one end of the LED, can reduce the current flowing through the LED and prevent damage to the LED.
formula
Current limiting resistor = (supply voltage - LED forward stable voltage) / required operating current