Physics Project Guidelines

Project Proposal: Sound Reactive LED

Description: Sound Reactive LED is a device that works with the beats and loudness of the music or sound. SRLED can be directly attached to the wirings of the speakers (the brightness of LEDs depends on the volume of the speaker) or connected to one jack of Y splitter from the source (the brightness depends on the volume of the source and not the speaker). The efficiency/output of the SRLED made depends on the creativity, style and electronic skills of students.

Minimum Materials: 4 or more LEDs (color may vary and depends on ), TIP31 transistor, wire, 3.5 jack (from old headphones are ok), AC adaptor/Transformer (12V)/battery/power supply, resistor any value

Warning: DO NOT PLUG YET YOUR OUTPUT PROJECT TO YOUR HOME OR ANY PLACE. WE WILL GIVE A TESTING DATE FOR THE OUTPUT!!!

Suggestion: BETTER IF YOU CONNECT FIRST ALL YOUR WIRINGS TO A BREADBOARD BEFORE SOLDERING OR FINALIZING YOUR OUTPUT!

Minimum Procedure:

1. Connect the LEDs in series (observe the polarity). The longer leg is the positive terminal of LED.

2. Connect the negative terminal of connected LEDs to the middle part (base) of the TIP31.

3. Strip the wires of your 3.5 mm jack.

4. Connect the ground wire to the rightmost of the TIP 31 and the white/any colored wire to the leftmost (emitter) of the TIP31.

5. Do not solder yet. Let’s see if it works or not. Present this during the testing day.

6. During the testing day, connect the positive terminal of the transformer to the positive terminal of the connected LEDs. Also, connect the negative terminal of the transformer to the rightmost part (collector) of the TIP31.

Observe the power and voltage rating of your LEDs. Series LEDs’ net voltage is just the algebraic of each voltage. The net voltage must be equal or below the voltage rating of the transformer so that your LEDs will work fine.

You can try to add a resistor of any value you want in series to the LEDs so that you can add more than 4 LEDs. I suggest try different resistors that can fit to what you want.