This Analog LED color organ is taken from this wonderful Instructable and was put together for Analog Electronics at CCA.
My instructable will be based on my building of the circuit on the breadboard and the PCB plus any additional complications/notes that happened to have come up whilst building it.
Step 1: Step 1: Schematic & Overview Construction on Breadboard
This LED Color Organ's purpose is to have LEDs react in brightness/dimness to certain frequencies (high, medium and low) from music that is input into the circuit.
I Initially built the Color Organ onto a breadboard: construction was easy and rather straightforward however I did decide to forego the optional second Audio input that was used by the creator of the schematic.
The Materials are as follows:
3x 100 ohm resistors
1x 180 ohm resistors
1x 270 ohm resistors
2x 1k ohm resistors
4x 2.2k ohm resistors
2x 10k ohm resistors
1x 0.047 uF capacitor
1x 0.01 uF capacitor
1x 0.47 uF capacitor
1x 1 uF capacitor
1x 10 uF capacitor
1x 1N4148 diode
1x 2N2222A, 2N3904 or equivalent NPN transistor
3x 2N2907A, 2N3906 or equivalent PNP transistor
I have left notes in the image of the schematic for a certain kind of NPN and PNP transistor: please make sure you are using the same transistors before taking the same notes from the schematic of what parts is what.
Another thing to note: after completing the circuit I used my phone as the audio input into the circuit and unfortunately not all of the LEDs emitted the brightest amount of brightness (Q2 and Q3 showing the least amount of light).
This could be because of two problems:
The audio input of a cellphone is not loud enough to send enough sound through the entire circuit
By foregoing the second optional Audio 2 from the circuit, there is less sound going through the entire circuit
On the breadboard you can try to build an amp for the circuit and see if that helps the LEDs.
Step 2: Step 2: Construction From Breadboard to PCB
This being my first time soldering onto a PCB I have encountered a few problems while constructing: be careful of what you are soldering together. My circuit did not work initially due to bad/faulty connections.
Here I have a picture of the LED color organ soldered onto the PCB. Unfortunately the same problem I encountered on the breadboard where the LEDs are working but not as bright as they should.
I noticed in this case Q2 shone the brightest as the others were quite dull.
Just as before I suspect this could be for the same reasons (cellphone sound input not being loud enough and omitting of audio 2) bur this could also possibly be solved with the installation of an amp. The image shows the circuit connected to a 9V battery and the inputs connected to the audio of the cellphone.