LED Beat / Etching PCB


LED Beat Flasher Components

This project takes in a sound wave and blinks the LED based on beats of the song. The LEDs are switched on and off by alternating its current using transistors. The transistors are alternating the LEDs current by sourcing its base pin with the song’s amplitude.


A couple weekends back, I spent some time with the Makers society at my school to learn how to etch my own circuit board using chemicals and the eagle cad software. The first step was to download eagle cad and begin designing our circuit. After designing our circuit with eagle cad, we printed out the circuit on a white sheet of paper. We used steel wool to scratch up the copper side of a copper PCB. We then used a laminator to melt the ink on the printed sheet onto the scratched up copper PCB. We then dipped the PCB into a chemical that I forgot (sorry, it’s been almost a month since I’ve made the board). We agitated the chemical to corrode the exposed copper, the copper that was not covered by the ink, for 15-20 minutes. We took the copper PCB and removed the corroded copper by using acetone. After letting it dry, we began to solder the components. Here is what the PCB looked like after removing the corroded copper with acetone:

LED Beat Flasher Protoboard


  1. 4 resistors
  2. 2 transistors
  3. 2 blue LEDS
  4. 1 red LED
  5. A male to female 2.5mm jack

Final Product:

LED Beat Flasher Full Image

Special Thanks:

Special thanks to everyone from makers society who taught me how to use eagle cad and etch my own circuit board. Everything from this workshop was free and it was definitely a great workshop! Thank you!