Saturday, 14 July 2018

DIY electric guitar

quote [ I wanted to run this all through the LittleBits Korg Synth kit, which would allow me to play with the signal in a lot of ways, and do all kinds of effects and stuff. ]

This is a DIY thing that Hozay asked me to post a while ago. It's a lot of fun, but hard to play 'well' because it isn't a real instrument. I basically just have a blast making noise with it. See extended for audio/video in action.

I like to come up with little challenges for myself, and the idea of making my own electric guitar seemed like a fun one that could end up with a cool result. To be clear, I don't have the proper tools to make a real, good, playable guitar. I just wanted to make an electric stringed instrument that was somewhat guitar-like. The main ingredient, of course, is the pickups, and that is what I wanted to learn how to make. I was also hoping it could be something that I could route through the LittleBits Korg mini synth kit, so that I could play with distortion and effects and all that.

The neck/body:
So far the whole guitar is just one long board with the pickups, bridge and all attached directly to it. I plan on adding something of a body at some point to make it more comfortable to play with in the future. It is just a piece of oak I bought from Lowes. I cut the board thickness of one end in half where I mount the tuning machines so that the strings go up and then have some break angle over the nut. I drilled 4 holes and mounted the tuning machines there, with some minor care into thinking about how the strings will actually have to go so they don't interfere with each other. It is not pretty looking.

The final nut is a piece of bamboo from my back yard sawed in half (temporary one in image is carriage bolt). The bridge is a pencil glued to the board. The strings are attached by a small bent piece of aluminum with holes drilled in it. I eventually did use an online fret calculator to figure out where hypothetical frets would go, and then just drew lines in pencil in those places.

The pickups:
The principle is extremely simple. You have a magnetic field around some copper coil and you disturb that field by moving a piece of metal (vibrating a string) within that field. The disturbances induce a current in the coil, which is amplified by an amplifier and turned in to audio by the speaker. There are plenty of good youtube tutorials on how to make your own pickups. I watched a couple and then went my own way from there.

I made a holder for the magnets out of two thin oak wafers that I sawed from a scrap piece created when I cut down the neck. I recommend finding a piece of plastic or something instead, because the oak kept snapping along the grain while I tried to drill the holes. Anyway, I evntually drilled 4 holes in each piece. 4 neodymium magnets went into the holes and were glued in place, and then the other wafer was fitted on top. The end result in profile looks like "IIII" with the magnets forming the vertical bars and the oak pieces forming the top and bottom horizontals. I drilled a small hole and ran one end of 42 gauge wire through it, and wrapped it (pictured below along with sewing bobbin pickup I made earlier) around the magnets. The easiest way to do mount the magnets in their frame on a bit driver (electric drill) and just spin it, allowing the wire to come off the spool as it wraps around the magnets.
After a whole bunch of coils (you have to be careful on this part- the wire is fragile and breaking means starting over) - maybe several thousand? - I packed it with hot glue to protect the wires. You should have two free ends of wire sticking out of your pickup.

Putting it all together:
The pickups have to go under the strings, and the coil has to be in some way connected to your amp. I had a 1/8inch stereo jack in an old pc speaker system so I just pillaged that, but they are dirt cheap to buy. If you already have guitar stuff, go with the 1/4 inch instead, since that's standard. I just so happened to have an amplifier I bought in high school from Radio Shack that had two 1/8 inch input jacks, so that's why I did 1/8. Anyway, the pickup only produces a mono signal of course, so I just soldered it up so that both stero channels on the jack are hooked up to the same end of the pickup wire. The wire is coated with some non-conducting enamel or something so I had to sand that off on the ends before soldering. But once everything was soldered securely I just hot-glued the whole shebang into some spaces I had cut out of the board for these items - the pickup and the jack.
I just so happened to have a cheap Radio Shack amplifier I had bought in high school with two inputs - one for 'aux' and one for 'mic.' Between the two, the 'mic' one had a lot more amplification. But whala, at this point you have an electric guitar.

Extended technique:
I wanted to run this all through the LittleBits Korg Synth kit, which would allow me to play with the signal in a lot of ways, and do all kinds of effects and stuff. The pickup doesn't produce enough signal for the little bits, so I still need to plug the guitar straight into the amplifier... but the amplifier has no output. The amp does have two input jacks though ('mic' and 'aux') so I just cut the wires to the 'aux' jack and routed new wires from the speaker terminals to that to serve as the new output. I chose to keep 'mic' as the input because that input gets a much stronger amplification than 'aux'. I also soldered in a toggle switch between the speaker and the amplifier circuitry so that I can have the amp on, with the speaker cutoff.(I don't want the distorted sound coming from the little bits to have to compete with the unaltered sound from the amplifier).

Now, to play through little bits, I connect guitar -> amp input, toggle speaker off, amp output -> microphone LittleBit. Then at the end of the LittleBit chain, there is a speaker bit for the final output. The speaker also has a 1/8 jack that I put a splitter on when I record so that I can have headphones and a direct audio line into my video recorder (smart phone).

SELINKS not working in preview, so check these videos to see/hear it in action. (vids in order from testing pickups through playing with effects)
[SFW] [do it yourSElf] [+6 laz0r]
[by robotroadkill@4:15amGMT]


mechanical contrivance said @ 1:26pm GMT on 16th Jul
That's not what I was expecting.
robotroadkill said @ 3:49pm GMT on 16th Jul
I tried to be forthcoming in that it's a piece of shit!
mechanical contrivance said @ 4:48pm GMT on 16th Jul
It looks like a fun project, in any case.
HoZay said @ 4:19pm GMT on 16th Jul
That korg looks like endless fun.
robotroadkill said @ 5:29pm GMT on 16th Jul
Got it for Xmas a couple years ago and have since supplemented it with some additional modules. It is a lot of fun, and I learned a lot just by experimenting with different setups.

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