Audio Guitar Tuner

Project  / Project number: 160/18  /  Status:

P1020503 reduced

The guitar tuner in use

The challenge

The invitation to do this came with a link to an existing project on the “Instructables” website:

  • – instructions to build

There was also a video showing it in operation:


I sent the video link to the client and, having watched it, he thought it would be helpful and asked me to go ahead.

Having an existing design to copy was most useful and, fortunately, both the guitar tuner and Arduino used in the original design were still available so the major part of the challenge was trying to find a neater method of assembly.

The solution

I looked around a small plastic boxes and came up with the Camden Boss 206 or 880-525 which seemed just large enough to fit the Arduino board in. I was very keen to keep the battery holder in its original place and I found that mounting the box on the rear of the tuner made this just possible. The box was screwed to the back of the tuner’s case with M2 screws and nuts and a hole drilled through for the wires. The box also houses a toggle switch which replaces the tiny one in the tuner (I felt that a visually impaired user would never find it reliably), the push button to select individual notes to be tuned and a 3.5 mm headphone socket.

I wired it all up according to the instructions and loaded the Arduino code and, magically, it worked as expected. The battery still fits in its original space in spite of the wires.

Pic 1: Inside the tuner – wires and diodes added.          Pic 2: Wiring to the Arduino, switches & socket.    Pic 3: The Arduino just fits in the box.

The finished tuner – front and ………… back views.

The benefit

I delivered it to the client who got the idea of how it worked very quickly. He didn’t see the need for the individual string push-button as his guitar was already very close to being in tune. I explained that he may need some help with changing the battery and that I have no real idea how long it might last and he worked out a way of remembering which way the toggle switch works to turn it on and – most importantly – off. I left it with him and he said he was going off to practice with it.

(I will add a picture of the client once the approval form is processed.)

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