LED Color Organ

Microphone Input and Amplifier:

When connecting the Microphone we initially had a hard time getting a signal to come through. What ended up helping our team was using the waveform generator and oscilloscope to check each component before moving on. We decided to connect two LM386N amplifiers specifically meant for audio to our circuit. This helped to refine and amplify our signal. Using two amplifiers also helped us avoid having an amplifier attached to each filter individually. 

Diagram:

Filters :

Lowpass Filter:

It took a lot of brainstorming to figure out what frequency we wanted to filter with our lowpass filter. We also had to make sure our circuit had enough voltage to light up the LEDs without overloading them. After doing calculations and observing last semester's examples we decided to use a 33kΩ resistor and a 10nF capacitor to build our filter. We also were going back and forth about whether to use one LED or two. We found that with one the filter was not as effective. 

Diagram:

Highpass Filter:

The circuit design process for the highpass filter was very similar to the lowpass filter. This design went very smoothly when we figured out which resistor and capacitor values to use.

Diagram:

Bandpass Filter:

The bandpass filter took lots of trial and error. Since we did not have inductors at our disposal we had to attempt to design a filter with just resistors and capacitors. We came up with lots of trial designs and in all of them, the LED was unable to turn off.  When we added a second resistor we were able to get to our final design. 

Diagram:

Final Filter: 

This is a demonstration of the final circuit working.