How to Make Sound Activated Leds

Sound activated LEDs can be adjusted so they only respond to loud noises.

Making your own sound activated light emitting diodes (LEDs) can be almost as fun as actually using them. Sound activated LEDs have many uses, from creating your own clap on, clap off light source to a light that comes on when someone knocks on your door. Most sound activated switches will have a method for adjusting the sensitivity to noise so you can have your LED light up at a quiet whisper or a loud yell.

Things You'll Need

• LED
• Soldering iron
• Solder
• Wire
• Sound activated switch
• 9-volt battery
• Masking tape

Instructions

1. Tape one end of a piece of wire to the positive terminal of your 9-volt battery.

2. Solder the other end of that wire to the anode (longer wire) of your LED.

3. Solder a second piece of wire to the cathode (shorter wire) of your LED.

4. Solder the other end of that wire to a terminal on your sound activated switch.

5. Solder a third piece of wire to the other terminal on your sound activated switch.

6. Tape the other end of your third piece of wire to the negative terminal on your 9-volt battery.

Tips & Warnings

• If the LED is not responding to your sounds try adjusting the knob on your sound activated switch until it becomes more responsive.

• Be very careful while soldering and be sure to have a stand nearby while the soldering iron is not in use.

References

• "The Art of Electronics"; Paul Horowitz, Ph.D., Winfield Hill, Ph.D.; 1989
• "Physics For Scientists and Engineers"; Randall D. Knight, Ph.D.; 2004