Creating A Low Pass Filter? (Color Organ.)

[Vulti]

Hi I'm pretty new to all this electronics stuff and I wanted to know if anyone could help me build a low pass filter connected to some LEDs. I'm trying to create some lights that flash to the bass of my music. Here are some features I want my circuit to use.

- Powered by 12v power adapter(ones you plug into wall.)
- Microphone for audio input.
- 8 flashing LEDs.
- toggle switch(on/off).

 

[crutschow]

Do you want all the LEDs to flash together?

 

[Vulti]

Yes I want them all the flash together, its just so the light is brighter

 

[gtr_stitch]

bass beat

hello
im not sure if you have figured out your project, but i stumbled upon your thread and thought maybe i could help...
attatched is a schematic of a guitar-led circuit. basically, the guitar is plugged into the input, and with every strum or pluck, the led comes on, and fades out as the note of the guitar fades out.
it's a pretty cool schematic i got from AudioGuru, and if you haven't figured out your project yet, this could be your first stepping stone towards it.
Hope I helped!

 

[MikeMl]

The circuit that Stitch posted will flash the LED for all frequencies, not just low ones.

Are you up to building a circuit with an opamp, a dozen resistors/capacitors plus your Leds?

 

[stl_jones@yahoo.com]

I've been looking at that schematic for a while and am having a hard time figuring out whats going on. Is this circuit going to have the LED's on 100% of the time during the music, not just the positive alternation?

I assume this is achieved through creating a virtual ground on the negative input of the op amp. Still, I'm fuzzy on how this op amp is holding the output high 100% of the time while there is audio inputed.

 

[audioguru]

The little audio power amp (it is not an opamp) produces a positive output that lights the LEDs during the positive peaks of the music.