This is an old revision of the document!
Circuitry
This project revolves heavily around electrical concepts. If you are new to electronics, I recommend using this website to help you understand more about them, if you would like to learn more.
Amplifier Audio Output
In order to route the audio output from the amplifier, we are going to want to create some wires that can attach to the audio posts included in this build. To do this, we will solder on the gold ring connectors included with the posts. Simply solder the wires on as shown below (left, and then add heatshrink to these connections to keep them safe from failure (shown below, right). The assembly section has instructions on how to attach there to the audio posts.
LED Circuit
The circuit that allows the LEDs to be timed with the sound is built using just one transistor and a set of inputs. Here is a circuit diagram to help understand how it works:
The input that comes from the amplifier will be that which comes from the terminal block soldered to the audio input of the amplifier. We do this because when using the audio output of the amplifier, the low frequency that is used to activate the TIP31 transistor is filtered out by the amplifier, so we use the computer's output instead.
Here is how the circuit should look setup on a breadboard:
Note: this circuit uses the output from the speaker. Use the output from the amplifier instead.
Once you have the circuit setup, test it out to make sure it works. Refer to the testing page for more info on testing this circuit.
After you know the circuit works, you can make some improvements to it if you want to. For my final circuit I used 6 LEDs, 3 red, 3 blue in parallel with each other.
Note: this uses 5 each instead of 3, but the principle is the same.
If you do different colors, make sure that you adjust for the different voltages using the appropriate resistors for the color and number of LEDs