Controlling a light-emitting diode (LED) with a ESP32 Third is the surprisingly simple project, especially when using a 1k load. The resistor limits one current flowing through the LED, preventing it’s from frying http://theengineerstore.in/products/12v-mini-spot-welding-machine-automatic-control-10awg-multiwire-portable-transistor-18650-lithium-battery-spot-welder