Is That A Tuner In Your Pocket…?

As a musician, it’s rare to consistently recognize with the naked ear whether or not a single instrument is in tune. There are a number of electronic devices on the market to aid in this, however if you’re leading into an impromptu performance to impress your friends, using one feels about as suave as putting on your dental headgear before bed. When tuning is necessary, why not do so in a fashion that won’t cramp your style?

To help his music-major friends add an element of Bond-like flare to the chore, [dbtayl] designed a chromatic tuner that’s disguised as a pocket watch, pet-named the “pokey”. The form for the custom casing was designed in OpenSCAD and cut from aluminum stock on a home-built CNC mill. Under its bass-clef bedecked cover is the PCB which was laid out in KiCad to fit the watch’s circular cavity, then milled from a piece of copped-clad board. The board contains the NXP Cortex M3 which acts as the tuner’s brain and runs an FFT (Fast Fourier Transform) that uses a microphone to match the dominant pitch it hears to the closest note. Five blue surface-mount LEDs on the side indicate how sharp or flat the note is, with the center being true.

[dbtayl’s] juxtaposition of circuitry in something that is so heavily associated with mechanical function is a clever play on our familiarity. You can see a test video of the trinket in action below:

38 thoughts on “Is That A Tuner In Your Pocket…?

  1. “As a musician, it’s rare to consistently recognize with the naked ear whether or not a single instrument is in tune.”
    False! It’s just a learned skill, which anyone who plays enough will pick up.

        1. Yes.

          Strings of a classical guitar for example stretch and slip over time between sessions, so while it’s trivial to tune them relative to one another for jamming by yourself, you need a known starting point. There’s tuning forks you can strike and place on the guitar body for reference sound, but a chromatic tuner is just much more convenient.

          Otherwise you’ll spend ages tuning one instrument, then tuning the next instrument to that, and then someone else comes along and starts playing 3/4 of a note higher and they have to tune their instrument as well…

          1. Age of strings can influence tuning as well, new strings can be stretchy enough that, when fitting a new set, the first string I fitted has dropped by half a tone by the time I tuned the last one

          2. New strings undergo plastic deformation and stress hardening for a bit before they become playable.

            But the effect is more down to the fact that when you remove all the old strings and start tightening the new ones in, you’re increasing the tension in the neck with each additional string, which makes it shorter and eases the tension on the previously tightened strings.

            Even with old strings, if you change the tuning, you have to do a couple passes before the tuning settles down because changing the total amount of tension changes the tuning of all the strings. If you want to do DADGBE instead of EADGBE, you have to go through all the strings and not just one.

        2. It’s also especially important on brass instruments, which can’t be tuned in fifths like a violin or guitar. I play French horn, and even though the main slides I adjust are for the F and B-flat systems, I can’t sound two notes simultaneously to tune them. Also, I occasionally need to adjust the 1-step, half-step and 1-1/2-step slides for both the F and B-flat systems.

          1. I remember one particularly cold day in marching band all the wind instruments had to tune as sharp as possible to try and match up with the marimba and other keyboards. I was glad I played trumpet and didn’t have to cut the fingertips off my gloves like some of the woodwind players.

      1. Perfect Pitch is rare, being able to identify one note isn’t. And once you have one all you need is relative pitch.

        PS I accidentally clicked on the “report comment” link and don’t know how to cancel it, maybe it should have an “Are you sure?” confirmation box.

          1. Only if you have everyone tune by themselves. You get one person in absolute tune, and then everyone tunes relative to them. Even if they’re wrong, everyone is wrong together so it doesn’t matter as long as the original person was in the ballpark.

          2. If you tune each instrument individually sure, but that’s not what I’m talking about. You can tune whole sections at the same time. With a little bit of practice most people can spot overtones and adjust accordingly.

      2. As for absolute perfect pitch across all registers, that is quite rare, but developing perfect pitch for one of two notes isn’t. I can call a lower E and D string on guitar pretty much perfect every time.
        Only with the E it’s trivial to tune the guitar by hearing alone and the D tells me if I was off of not. Tuners mostly agree with me!
        As a consequence of being able to pinpoint a specific E and D, can often guesstimate higher and lower E’s and D’s and thereby disassemble notes and chords in music i hear, which is easy for figuring out the score.

  2. It is worth noting that it is far more important for an instrument to be in tune with itself, and for instruments played together to be in tune with each other, than it is they be tuned to any particular pitch. In fact, the standardization of A440 is a relative modern one, and historically the A above middle C has been anywhere between 415 Hz and 466 Hz.

    1. There is the point that modern instruments are built with A440 in mind, so if the tune is offset from the standard, you don’t get the same resonances and the sound of the instrument changes.

  3. Other than aesthetics I fail to see how this differs in operation from any other standard tuner. However if the author added vibration to the mix then the tuner could be kept in the pocket while performing its function. That way one could pretend to actually have perfect pitch! :-)

    1. This is exactly what I was thinking. Perhaps a short pulse for sharp, a long pulse for flat and a quick double pulse when you’re in tune? Maybe even a magnetic ring to turn it on and off so you don’t even have to reach into your pocket.

    2. It’s not supposed to be different from any other tuner, it’s supposed to be not a store bought tuner.

      It’s also smaller than all the tuners I’ve ever seen, but it’s not like I’ve gone looking.

  4. Ha! I knew this article would get bashed with the “a true musician wouldn’t need that” statements. While this is true, sometimes it just helps to have something like this. People age too, so if you are able to do this now; you might not when you are old.

      1. You may want to check your phone’s “tuning” against a dedicated chromatic tuner. my android phone is off by several Hz and renders itself useless for tuning my bass…

        1. “Several Hz” is really that big of a deal? Besides, if it is consistently off, can’t you offset that one way or the other? I would assume at least a couple among the dozens of tuning app developers would know a thing or two about tuning?

          1. “Several Hz” is the difference between sounding in tune or not. Those with perfect pitch can come very close or hit it dead on, but why not use technology to be perfect every time? I find myself playing guitar along with synthesizers and nothing is worse than the guitar sound going sour the moment a synth comes in, just due a tiny difference in intonation.

        2. Do most (or even any) apps have some means of adjustment? And if they did, what do you tune them with? I am guessing you would want to tune your tuner with a known good tuning fork.

      2. For ukes and guitars and other instruments with an appropriate-shaped flat head, it’s much easier to use a clip-on tuner, because it only picks up the vibrations from your instrument, not all the sounds in the air from the other musicians, people talking, the TV on the other side of the pub that’s playing music during a commercial, etc. (You can do the same by plugging in a contact-pickup to the Korg tuner shown in the back of the second picture above, but the pickup and tuner each cost about the same as a clipon tuner, and it’s more awkward.)

        For less cooperative-shaped instruments like most of my dulcimers, I used to use a Korg, but most of the time I use a cellphone app instead – it’s more sensitive (which is bad, because it would often rather tell me some random harmonic than the base note), glows brightly instead of being flat LCD, changes colors when it’s sharp, flat, or ok, but most importantly, it’s something I’ve always got with me anyway.

  5. Author here, I’ll try to clear up questions…

    -No contact mic or line-in, unfortunately. The friends in question are brass players, so line-in wouldn’t be the most helpful for them, not to mention not physically fitting in the enclosure. A contact mic would be awesome, but last time I checked they cost more than all of the materials that went into this build combined.

    -Vibration would be cool. I’m assuming they can hold it by their bells and still see the LEDs… that may or may not be justified. Again with the space concerns, though. There MIGHT be enough space if I cut out more of the aluminum under the PCB by the hinge. I guess mostly I didn’t think of it.

    -It doesn’t function any different (and probably performs overall worse than) a regular tuner. It just looks snazzy. The whole thing is kind of a moot point since, as many have pointed out, musicians are good at tuning themselves, and these two are no different. Perhaps more relevantly, they both have phones with tuner apps. So it’s more a solution to “I want to make graduation presents for these guys” than “these guys need tuners”

    -Re “OMG BLUE LEDS!”: The one shown is blue, the other one will be red, as soon as I solder it up. Fortunately my friends’ favorite colors are common LED colors. And the battery charging LED is obnoxiously bright green. I should probably put a bigger resister in there, but I kind of like it that way. I probably should also make the sharp/flat LEDs different colored from the “in-tune” one, but that would require redoing the board (individual resistors for LEDs due to different voltage drops based on color).

    -There’s a USB port on there (on the side of the case not shown in the title image), but all it does is charge the battery. The data lines aren’t connected to anything.

  6. Strobe tuning is old science. Why it is not used is more than some 40 year old patents lying around. This patent had just 8 LED’s in a circle with a ninth in the center to show sharp. Strobeing is the visualization of the actual beat of the reference and the to be tuned. Converting the beat frequency to (meter range) or worse, flat-sharp with no magnitude display (three LED) is lame. At least make the center LED flash the beat when the beat is below 10Hz.
    It would be a piece of cake to put a non-linear amp (or-ing) the reference and tuned, not to drive a neon or LED but a hard disc arm motor and be able to feel that beat hidden in a pants pocket.

      1. Apparently they are widely used. It’s just that you can get a fairly decent cromatic tuner for about $20 and they’re perfectly adequate for amateur players.

        And some of the cheap strobe tuners are actually chromatic tuners that simply mimic a strobe tuner.

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