This is the wiki page for a project TP is thinking about.
I would like to build a giant VU meter (like, wall sized, maybe 10 feet tall?) using electroluminescent tape (EL) or similiar (maybe some other kind of lighted panel would be cheaper?). For those that attended the grand opening party, there was a guy walking around with a very cool light-up t-shirt that was exactly what I'm talking about, only *slightly* smaller.
http://www.instructables.com/id/LM3915LM3916-VU-Meter/ shows a project to build a simple VU meter that measures overall volume from an audio source (a single bar that bounces to the loudness of, say, a song). This is basically an analog circuit that outputs directly to an array of LEDs, although with the right output stage we could make it run just about anything (EL tape, desk lamps, etc).
Expanded Basic Meter
The meter I really want to build is probably better called a panel. I want to place 8 bars into a grid shape, and tune each bar to just a portion of the frequency spectrum (bandpass filters). We've all seen this somewhere before - the coolness comes from making it 10 feet tall, right? This expanded version of the above meter is really just eight of those meters each being feed from a seperate bandpass filter.
The next level up idea would be to multiplex the output of the bandpass filters into a PIC or similiar microcontroller's ADC for sampling. This might be not be possible, but there could even be a way to use a phase locked loop (PLL) circuit to run all eight bandpasses from a single spot, negating the need for multiplexing (hella research needed; PLL is the way modern digital radio tuners select band frequency for our favorite radio stations). Anyway, the controller could then light the appropriate output lights, probably by setting an externally scanned memory location or toggling inputs to a massive latch array, so that instead of a VU meter/panel what we really have is a 10' tall 8x8 monochrome screen that just happens to be running a VU program. The cool part of going this extra step is we can add things like a startup splash screen. We could also select between different output routines for variety (horizontal vs. vertical vs. radial vs. ?). The display pixel resolution may need to be increased past 8x8 - at least to the point of being able to draw a Hive13 logo on it or something. The price of the glow tape is based on area I think, so it /may/ not add *too much* to the price of the project to get a resolution of 64x64 or even 128x128. The design rolling around in my head right now has a max res of 256x256, but the approach may be too slow and I haven't so much as found a sheet of paper yet. If we end up with some other kind of lighted panel square adding massive resolution could end up (relatively) increasing the price much more, although overall it still may be cheaper than the EL tape.
This project is currently in the early planning stage.
- These tape sellers are hard to get prices and samples from. Half the websites don't list prices, or don't offer small quanities, or require you to buy some expensive power supply with your tape (I intend to make my own supply - the tape requires an AC current).
- The sites that do list prices show that this stuff ain't cheap.
- Find a tape sample (good luck)
- Play with tape sample
- Build cheap LED version (cheap cheap cheap - I can fund this)
- Get enough Hive members excited about project so that I can get the funds to build Giant version onto a wall at the Anchor space?