How would I rig my acoustic guitar to glow red whenever Em is played?

Question

How would I rig my acoustic guitar to glow red whenever Em is played?

Answer 1

You'd be better off stepping on a pedal every time you hit Em.  Have the pedal hooked up to a big red LED or something.

Answer 2

I am posting this on behalf of my good friend Kabum, whom Yahoo has cut out of the Answers game with their recent update. All kudos should be directed Kabum's way.

Piece of cake!

All you need is a string of red xmas lights (or those cool chili pepper lights – my preference), a cheap Korg tuner, a PIC microcontroller, an old stereo boombox with a built-in microphone, and an (Analog Devices) AD620 instrumentation amplifier chip (each 8-pin DIP retails for about $12, pricey  Ã¢Â€Â“ but it has a great CMRR and an external ouput reference which can be used to virtually eliminate ground loops and hum).

Start by extricating the CD changer mechanism in the boombox, including the spindle drive, laser unit and whatever board has the DAC circuits. It’s a simple matter of finding the audio inputs on the main board that the CD audio signal was fed into.  This will serve as the port of entry of the Korg. Attach the microcontroller at the solder points just to the left of where you attached the Korg. I’m pretty sure this is right.

Disable the A and D sensors of the Korg unit so that  only the E, G, B and E sensors that form the Em chord remain. Wire the adapted Korg into the DAC circuit board via the PIC microcontroller solder points. Output to the lights is via the AD620 amp.

Output is somewhat buffered by the instrumentation amplifier. Since the AD620 requires only one external resistor to set gains of 1 to 10000, you can use an unused  resistor from the DAC board to achieve just enough gain to power the lights. Drive the lights from the output circuit of the DAC.

It’s probably easiest to just stuff the lights in through the soundhole and if you pull the strap peg from the lower bout and swap it with a 1/4” input jack you can run the power cord directly out the bottom of the guitar and into the DAC.

Set the boombox to AUX or CD, strum or pluck the E chord within range of the microphone and voila! Red lights!

I haven’t tried this yet, but I saw a hooker in Waikiki do it with a ukulele and she was attracting all sorts of attention.

Kabum

Answer 3

Place a red light in the soundhole? lol, what an interesting question.