Blink some LEDs with a 555 timer

One of the first projects of every evil and mad scientist is making some leds blink. After all no evil mad scientists lair is complete without big controlepanels with blinking lights. This video shows you how to connect some LED’s and a 555 timer together to get the much desired blinking effect.

For this project you’ll need:

  • a 555 timer
  • 2 LEDs
  • 2x 150Ω resistor
  • a 1MΩ resistor
  • a 100KΩ resistor
  • a 10µF polar capacitor
  • a breadboard and some wires

The frequenty of the blinking can be calculated with the following formula

f = 1.4 / ((R1 + 2R2) + C1)

The cycle can be divided into 2 parts: Output high and output low (sink)

The formula to calculate the output high time is 0.693 x (R1 + R2) x C1 and the formula to calculate the ouptut low time is 0.693 x R2 x C1.

The duty cycle has to be at least 50% so the output high time cannot be shorter than the output low time.

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