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Troubleshooting my first electric guitar build.

Hi. New here. In a fit of apparent madness, I started building sort-of an electric cigar box guitar using the designed published in Make Magazine a few months ago. You can find it here: http://makezine.com/projects/make-37/license-plate-guitar/

It's my first guitar, so as you can imagine I've run into some troubleshooting problems. I've completed the build and soldering, but can't get sound to come through my amp. The electronics include a hand-wound pick-up, a potentiometer/dial, and a pot. Basically, when I string up the guitar and plug it into the amp, no sounds comes through regardless of how high I turn up the volume. When the dial on the guitar is turned all the way up and I tap the metal rods of the pick-up with a magnet, I can hear that sound through the amp though, so the wiring is (hopefully) correct?

I was hoping someone here could help me troubleshoot this. Am I missing something obvious (likely)?

I can dig up some pictures if that would be helpful.

Thank you.

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Permalink Reply by the anonymous pick on July 29, 2014 at 3:07am

pictures and more info may be helpful .. ie are you using nylon strings maybe ? ;-) and how high above the pickup are the strings ? could be something as simple as this .

and who wound the pickup ? how many winds ? what kind of magnet ? does sound come through the amp with just tapping a metal screwdriver on the pickup poles ? ?

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Permalink Reply by The Phrygian Kid on July 29, 2014 at 3:29am

Does it make any noise when you tap it with something which is metal but is not a magnet .? (Eg key, screwdriver etc)
My first thought is that you wound a perfect coil but then forgot to stick a magnet on it. It needs a magnet to work ;)

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Permalink Reply by jabes on July 29, 2014 at 4:46am

i see from the 'Make instructions to use 20 gauge wire - is that a tad thick ? i made a pickup with wire from a transformer that was thick and it nearly worked..v quiet.

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Permalink Reply by Amanda Potter on July 29, 2014 at 6:31am

Thanks for the quick response. I've got some picture below. The guts are a bit disassembled because I want trying get things working. When I had it hooked up before, touching metal to any metal part of the guitar was causing a static-y hum to come out of the amp. I think when I tapped the pick-up rods with metal, but not a magnet, I was getting the tapping sounds through the amp as well, but I'll have to double check that.

First, this is how high the strings are above the pick-up. I bought the strings as a set from CB Gitty and they were marked as electric guitar strings. They are metal. I tried holding the strings down close to the pick-up, but that didn't seem to help.

Next, the guts. When I was testing it, I had tiny rare earth magnets (3/16 in each) attached to the bottom of the pick-up rods and the wires connected to the pickup as well. The pickup was wrapped with 22 gauge magnet wire and about 40 ft of it (I just used up the roll I bought, so I didn't count the wraps). It's disconnected in the picture because I tried making a second pick-up (below) since I thought maybe my gauge was too large.

These are pictures of the second pick-up I wound. I used a 30 gauge magnet wire on that one and again just used the entire roll. I think it's 200 ft if I found the right thing on Radio Shack's website. I glued the rare earth magnets from the pick-up above to this one, but haven't install it all the way because I wanted to be sure it would work first (also I used superglue on the first one, so have to figure out how to get it off). I tried connecting the wires and holding the pick-up really close to the strings and strumming them, but had the same results.

Something I was wondering about winding the pick-ups is does it matter how the wraps overlap? I tried to wind it like thread around a bobben (one layer up, one layer down, repeat), but wasn't sure if that was right.

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Permalink Reply by JL on July 29, 2014 at 6:51am

Start with "Assume Nothing". I can't tell you how many times I beat my head against a wall and eventually found the problem was located someplace I assumed it couldn't be because of ...<insert foot in mouth here>.

1. does that amp and cable work with another instrument?

2. Is the audio plug mono or stereo? (2 or 3 lugs to solder to). If it is a stereo audio plug, are your wires soldered to TIP and SLEEVE and RING is unused?

3. plug one end of the instrument cable into the amp and turn the amp on. Tappy-Tap your fingers on the exposed 1/4 in plug at the other end of the instrument cable. With the amp on, you should hear noise.

4. open your CBG to expose the wiring and then plug the instrument cable into the CBguitar's audio jack. With the amp on, you should hear a noise as the connector goes in and makes contact.

4. Tappy-Tap your fingers on the audio jack solder points. with the amp on, you should hear noise.

4. Tappy-Tap your fingers on the volume POT solder points with the amp on and you should hear noise.

5. Tappy-Tap your fingers on the hand wound coil's solder points, you should hear noise.

Hopefully this will help you narrow it down?

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Permalink Reply by ChickenboneJohn on July 29, 2014 at 7:51am

I'm no pickup winding expert, but typical pickup wire gauge is 42 or 43 AWG. 22 AWG is around 10 times thicker. Also, a typical pickup will have 8000 winds of 42 AWG wire on it, so that's maybe around 3000 feet of wire..so I'm thinking a combination of the wrong wire and way too few winds is your main problem. The resistance of 22AWG is very low, about 1/100 of that of typical pickup wire (and 30 AWG about 1/10 of 'normal' pickup wire), so I don't think these factors will be helping you get the strings to induce any meaningful signal in the coil.

Also, that volume pot wiring doesn't look like any wiring I've seen...nothing grounded to the back, so not sure if that will work. It's always best to be systematic - take the volume pot out of the circuit and test the pickup alone. Also test the pickup with a multimeter to ensure you're getting a resistance in the order of 5k ohm or more. A multimeter is cheap and absolutely essential for this sort of work.

Interestingly, ages ago I was asked by Make Magazine to write the article for them, but I couldn't fit it into my schedule...and I don't know who the author is.

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Permalink Reply by Ron "Oily" Sprague on August 6, 2014 at 1:49am

James Rutter and Matt Stultz authored the Makezine piece referenced above.

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Permalink Reply by BrianQ. on July 29, 2014 at 4:25pm

Yes! I agree Chicken bone,a bit different grounding technique. Maybe you should browse the wiring diagrams in the CBG Wiring & Electronics Group, it maybe helpful? give it a try, btw nice CBG.

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Permalink Reply by Amanda Potter on July 29, 2014 at 5:49pm

Thank you for all the suggestions. I'll have to hunt down a multimeter, but I'm sure I'll be back with more questions. Maybe I can temporarily rig up my sewing machine to make winding the pick-up again a bit easier, if that's what I need to do.

Stuff I can answer right away:

- I'm assured by the owner of the amp that it does indeed work; but I agree with "assume nothing". I'll double check.

- The audio plug has 3 loops to solder to, but I've only used 2. Does that make it stereo? I thought I had bought a mono one.

Thanks again. :)

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Permalink Reply by ChickenboneJohn on July 29, 2014 at 6:17pm

If the jack socket has 3 tags, it's stereo. You want to wire the "hot" from your pickup / volume control to the tag that engages the tip of the jack plug, and the ground to the tag to contacts the barrel of the jack plug, and leave the other one unconnected.

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Permalink Reply by Richey Kay on July 29, 2014 at 6:43pm

Hi Amanda,

I think most of your questions have been answered here, but here are a couple of pointers from me:

Your first pickup should have worked - the wire is thick and it would have a weak output, yes, but it would still have some signal. Most likely a wiring problem somewhere. I had a look at the wiring on the MAKE website and it looks a bit dodgy. For a start there's no connection to the back of the pot for the ground, and if we're assuming white = hot and red = ground, the connections on the jack are the wrong way round... the ground wire should connect to the tip.

Have a look at this diagram from Mr. Crocker, tried and tested:

You can just ignore the tone pot. Compare this to the wiring you have and have another go. Your first pickup should work.

Putting strong magnets on top of the pickup might work but might also affect the strings ability to vibrate - effectively killing sustain.

When you wind a pickup - don't worry too much about where the winds go - just fill the bobbin and make sure you keep the winds nice and tight, although when you use thinner wire like the more standard 42AWG, be careful not to break it.

If you want a bit of a bluffers/beginners guide to pickup building, I blogged my first couple of experiences here:

http://www.cigarboxnation.com/profiles/blogs/my-first-2-weeks-of-pi...

(There is a 2nd part linked at the end of the 1st)

Good luck!

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Permalink Reply by JL on July 31, 2014 at 7:46am

If you soldered to the RING and SLEEVE on the audio connector you will definitely get no sound since there is nothing connecting to the TIP of the instrument cable.