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Binary Rock

  1. 2015

2015-04-14 - Acrylic Guitar Project

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  • Cheap $150 acrylic guitar acquired on eBay

    Cheap $150 acrylic guitar acquired on eBay

    Oh good, thank god the hardware's not gold, that would be gross

  • Drilling holes to mount Luxeon 3W RGB LEDs

    Drilling holes to mount Luxeon 3W RGB LEDs

    Side note: That hardware sure is gold, ugh

  • Tapping the screw holes

    Tapping the screw holes

  • LEDs mounted and wired up

    LEDs mounted and wired up

    CAT5 cable proved really hard to solder, so I grudgingly used crimp connectors. I'd love to revisit this and route the wiring through the inside of the guitar

  • Designing the PCB to house the Arduino Pro Mini, MIDI interface hardware, and LED drivers

    Designing the PCB to house the Arduino Pro Mini, MIDI interface hardware, and LED drivers

  • PCB etched

    PCB etched

  • PCB all soldered up

    PCB all soldered up

  • PCB destroyed when I tried drilling holes in the enclosure with the PCB mounted, and the drill bit caught the enclosure and sent it flying across the garage

    PCB destroyed when I tried drilling holes in the enclosure with the PCB mounted, and the drill bit caught the enclosure and sent it flying across the garage

    I scavenged the screw terminal blocks from it and started again

  • Etching second PCB

    Etching second PCB

    As long as I had to remake it, I went ahead and added a terminal for a status LED and a 1N5820 Schottky diode for reverse voltage protection (only drops about 450 mV, versus 1V+ for a regular rectifier diode like a 1N4001)

  • It's so time consuming drilling all those holes

    It's so time consuming drilling all those holes

  • Second PCB all soldered up

    Second PCB all soldered up

    Not pictured: I ran into trouble getting the Arduino to chew gum and cross the street at the same time (i.e. read incoming MIDI messages while smoothly updating the PWM for the LEDs). The project was shelved for a few years.

  • 2 years later: Testing replacing the Arduino with the Raspberry Pi 2 B

    2 years later: Testing replacing the Arduino with the Raspberry Pi 2 B

    The RPi is much better suited to this task. A multi-threaded python script can comfortably do both tasks at the same time.

  • It works!

    It works!

  • Roland GK-2A MIDI pickup mounted

    Roland GK-2A MIDI pickup mounted

  • Preparing to replace the bridge and neck single-coil pickups with humbuckers

    Preparing to replace the bridge and neck single-coil pickups with humbuckers

  • New outlines scribed

    New outlines scribed

  • Cutting the larger holes in the pickguard

    Cutting the larger holes in the pickguard

  • All done

    All done

  • Humbuckers soldered and installed

    Humbuckers soldered and installed

  • Drilling more depth for the pickup adjustment

    Drilling more depth for the pickup adjustment

    These humbuckers are quite a bit hotter than the single coils, and I can't adjust them low enough to sound good. The answer: Drill, baby, drill! (I hate myself)

  • Pickguard enlarged for MIDI pickup

    Pickguard enlarged for MIDI pickup

    Another problem was that the MIDI pickup (mounted on top of the pickguard) was less than a millimeter from the strings. I had to raise the action a bunch just to get them off of the pickup, but even so, they buzzed terribly. The answer: Cut away that section of pickguard, so the MIDI pickup can sit lower, on the guitar body itself

  • Everything re-installed

    Everything re-installed

  • That's much better clearance now

    That's much better clearance now

  • But wait! Now the humbucker mounting ring is the problem

    But wait! Now the humbucker mounting ring is the problem

  • A quick solution

    A quick solution

    I considered sanding down the mounting ring so it wouldn't sit so high. But I was tired of half-measures.

  • Now we're talking

    Now we're talking

  • Etching PCBs is such a pain. This time around, I just opted for perfboard

    Etching PCBs is such a pain. This time around, I just opted for perfboard

    The board takes 9V DC as input, which feeds three LM317's configured as constant current sources to send 350 mA to the red, green, and blue components of the two RGB LEDs. At the same time, a 7805 linear regulator (now replaced with a switching regulator equivalent) steps the 9V down to 5V DC to power the Raspberry Pi.

  • Just a shot of the solder side of the board

    Just a shot of the solder side of the board

  • Planning the layout in the enclosure

    Planning the layout in the enclosure

    With Radio Shack gone, I had to make do with the largest enclosure I could find at the local electronics supply store, which is just barely big enough. I'll have to stack the two boards to get it to fit, and even then I'm not sure it will work

  • Trying to find a layout that works

    Trying to find a layout that works

    I could probably get away with this if I'm really precise in my drilling, but at this point tests showed that the 7805 was getting very hot producing the 5V for the Raspberry Pi, and a heat sink doesn't fit in this tight enclosure. That's also wasting a good chunk of the limited power I've got available. So I decided to order a 5V switching regulator from Mouser to replace the 7805, and as long as I was doing that, I decided to order a larger enclosure as well.

  • Drilling the holes in the new enclosure

    Drilling the holes in the new enclosure

  • USB passthrough mounting hole

    USB passthrough mounting hole

  • Drilling the power jack mounting hole

    Drilling the power jack mounting hole

  • Everything fits much more neatly in this enclosure

    Everything fits much more neatly in this enclosure

    Also note the 7805 near the top right corner of the perfboard has been replaced with the switching regulator, which works very nicely. 1.5A current output and cool to the touch.

  • All hooked up

    All hooked up

  • A shot of the front of the unit

    A shot of the front of the unit

    The red LED comes on as soon as power is applied, and the green LED is turned on by the Raspberry Pi when the Python script is running

  • Adding a 1/4" jack connected to the RPi's 1/8" audio output

    Adding a 1/4" jack connected to the RPi's 1/8" audio output

    I got the genius idea to use the Raspberry Pi as a synth as well, using FluidSynth, to eliminate needing to carry a separate keyboard. This hasn't worked very well so far though -- the synth sounds terrible and has very high latency -- so I'm abandoning that idea for now. But I have another use in mind for that 1/4" jack...

  • A shot of the rear of the unit with the 1/4" jack installed

    A shot of the rear of the unit with the 1/4" jack installed

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