How to Make a Blinking Warning Light with LED Indicators

Choose your LED

Place a Red LED Redstone Indicator, Green LED Redstone Indicator, Yellow LED Redstone Indicator, or White LED Redstone Indicator where you want a steady status light. For a flashing warning, use the blinking version of the same colour: Red Blinking LED Redstone Indicator, Green Blinking LED Redstone Indicator, Yellow Blinking LED Redstone Indicator, or White Blinking LED Redstone Indicator. Blinking variants flash on their own whenever they receive a redstone signal.

Drive the indicator

Run redstone dust from your trigger to the LED. Any redstone source works: a Glass Button, an Industrial Lever, a Rustic Pressure Plate, or a Glass Contact Plate. For a hands-free trigger, use an Industrial Infrared Entity Detector or a Glass Linear Laser Entity Detector aimed across a doorway.

If you want the LED to blink only when a machine is running, place an Industrial Comparator Switch between the machine's redstone output and the LED. The comparator passes the signal through, and the blinking LED handles the flash pattern itself.

To build a two-colour panel, place a Red LED and a Green LED side by side and feed them from opposite sides of an Industrial Lever. Flipping the lever lights one LED and darkens the other, giving a clear on/off readout for a door, gate, or machine.