I think the more typical approach is to use a quartz crystal oscillator for a clock and then divide down to attain the needed frequencies. I suppose the clock speed must be chosen to have all 6 frequencies as factors so that you can divide by integers. (Just my speculation.) You don't need a separate circuit for each tone, just one adjustable circuit.

I am doing a project called 'Guitar Tuner Circuit, in which I should not use microcontrollers, IoT, or software tools. My challenge is to build hardware with analog circuits, some ICs, and some logic to replace the microcontroller's place. I have no idea how to go on with this project, does anyone have any idea about this, please reach out.

Mods Note:
This post was split from here.

 

An explanation of the "Tuning" process will help those of use who are not aware of how a PLL enters in to setting a guitar frequency. The last "tuner" I used had a drum with marks and a strobe that flashed at the note played frequency. I think it was a neon strobe because the light was orange.

 

Looks like the whole class is lost.

 

Doesn't a musician or singer use their hearing to tune an instrument or their voice to an accurate beeper or whistle?
Except today, pitch-deaf musicians use Autotune to play the music in tune, and the singer (Drake) simply reads the lyrics and Autotune plays the song.

 

I am doing a project called 'Guitar Tuner Circuit, in which I should not use microcontrollers, IoT, or software tools. My challenge is to build hardware with analog circuits, some ICs, and some logic to replace the microcontroller's place. I have no idea how to go on with this project, does anyone have any idea about this, please reach out.

Mods Note:
This post was split from here.

How accurate must the tuner frequency be?
How many different frequencies do you need to produce?
How do you want to compare the acoustic signal to the tuner frequency?
What do you want to use as an indication when the instrument is tuned to the correct frequency?
Is it for electric or acoustic instruments, or both?

Without this information, any suggestions will be just wild guesses.

 

The exact frequency of the lowest note on a standard guitar tuning, being E2 is 82.41 Hz. The next string is 110 Hz which is 5 semitones higher, being A2 which is two octaves lower than A which is 440 Hz which is the standard note used to tune from. With 12 notes in an octave each successive semitone is the twelfth root of two higher frequency.

Once you have tuned the 82.41 Hz lowest note you can tune the other strings from it. The human ear can distinguish about a quarter of a semitone so the lowest note needs to be tuned within +/- 1Hz. Dividing 32.768kHz crystal by 400 would be close enough

 

The simple and one crystal scheme to be able to set the tuning on any instrument is a frequency counter with a display hold function. Then a lookup-table to know the correct frequency for each note. You will need an amplifier and a microphone to transform the sound into a signal to drive the frequency counter.
The crystal will control the time base for the counter, and the counter will need to have probably 5 digits so that the frequency can be read to the teenth of a hertz. So the timer will need five decades and both a one second and ten second time base.

Counting frequency is the least electrically complex scheme for an accurate tuner.

An alternative is to get a "top octave" generator IC, and then use binary dividers to produce all of the lower tones. Then a PLL could be used to show the error between the selected reference and the measured tone frequency. That scheme will require switching to select the correct octave and the desired note. AND it would require the same sort of input signal conditioning as the frequency counter scheme.

 

The human ear can distinguish about a quarter of a semitone so the lowest note needs to be tuned within +/- 1Hz.

Maybe some people are tone-deaf because they are aliens and are not human?

 

Maybe some people are tone-deaf because they are aliens and are not human?

Eh? Wassat? How did you guess? QI'yaH !

 

Except today, pitch-deaf musicians use

Today pitch deaf musicians (or so they like to think themselves to be) use computer generated music. Anyone, even someone with a tin ear can generate - um - music. But it's not like the days of old were the musician tuned his instrument using a tuning fork to set - I think it was - a C note. From there on a guitar, using the frets to tune the rest of the guitar. Then a strum of a known note would help the true musician to know if something needed further tuning. Like the bridge. Yes, you don't only tune the string you can also tune the bridge. At least in some of the higher end guitars.

Pianos, yes, I've tuned them too. A bit different, but the process to the ear is the same. When a note is in tune it harmonizes with the next octave. If there's a wavering tone then you know the string is not yet tuned. It's only when the note becomes one harmonious tune that it's tuned properly.

Not only have I tuned musical instruments, I've also tuned cars. I've tuned many things. But the one thing I couldn't tune is I could never tuna fish.

 

Maybe some people are tone-deaf because they are aliens and are not human?

Some folks have damaged hearing because of the explosions they heard while walking thru the jungle defending their country. And some of us went into engineering instead of music for our career. But I can read a frequency counter very well.

 

Some folks have damaged hearing because of the explosions they heard while walking thru the jungle defending their country. And some of us went into engineering instead of music for our career. But I can read a frequency counter very well.

Even deaf people can still enjoy music. Mostly they can feel the beat and deep base notes that cause the body to resonate.

Some folks have damaged hearing because of failure to protect their hearing while playing rock and roll drums for eight years. A decade ago my wife bought drums and I LOVED them. But my tinnitus was getting worse by the day. I had to sell them. Sold them to a young kid. His parents came with him. As he played - pretty talented kid at that - I told him this: "I'm going to give you some advice. If you take it you'll probably never thank me. But if you don't - you'll wish you did. Wear hearing protection." Then as I told him the reason why I was selling my drums he could see me choking up. He must have known at that moment that protecting your hearing is very important.

As for tuning a fish - sorry Pete - I've never had the chance. But that old piano my brother had stored at mom's house - I tuned that thing up without anyone ever telling me how to. Turned out quite well at that. But I used an electronic keyboard to synthesize the notes and matched the strings to the keyboard. When I ran out of keyboard I just used the next nearest octave to find the rest of the tune for the higher and lower octaves. That's the closest I've ever come to using electronics to tune an instrument.

 

I REMEMBER that old piano. YOU tuned that up? DANG! Good job. Bet you wish you had it now.

 

Brother "R" took it when dad died. Don't know what ever came of it after that. R just took it because he knew it meant something to me.

 

Even deaf people can still enjoy music. Mostly they can feel the beat and deep base notes that cause the body to resonate.

Some folks have damaged hearing because of failure to protect their hearing while playing rock and roll drums for eight years. A decade ago my wife bought drums and I LOVED them. But my tinnitus was getting worse by the day. I had to sell them. Sold them to a young kid. His parents came with him. As he played - pretty talented kid at that - I told him this: "I'm going to give you some advice. If you take it you'll probably never thank me. But if you don't - you'll wish you did. Wear hearing protection." Then as I told him the reason why I was selling my drums he could see me choking up. He must have known at that moment that protecting your hearing is very important.

As for tuning a fish - sorry Pete - I've never had the chance. But that old piano my brother had stored at mom's house - I tuned that thing up without anyone ever telling me how to. Turned out quite well at that. But I used an electronic keyboard to synthesize the notes and matched the strings to the keyboard. When I ran out of keyboard I just used the next nearest octave to find the rest of the tune for the higher and lower octaves. That's the closest I've ever come to using electronics to tune an instrument.

Some folks have damaged hearing because of loud noises while walking thru the jungle IN HELL. (a really nasty place at the time) The name for those who wore hearing protection doing that (wearing ear protection while walking in the jungle) would be in the casualty list. That is to say, dead. Situation awareness is especially important.

 

It seems that there are quite a few ways to tune a guitar. Frequency measuring, frequency detection, and reference comparing. Possibly others as well.
Which process is the TS seeking????

 

I think the simplest and most accurate solution would be a frequency counter with a 1 second timebase and an audio amplified input.
There are lots of circuits on-line for getting a 1 second delay by counting down from a 1MHz crystal. Use that as the gate for a decade counter with digital display that has the guitar signal as an input. This solution would give accuracy to 1Hz and would work for tuning any string, with a simple note/frequency table.
Note: Without those restrictions, I would make a much simpler version, using a ATmega328 uC, a 386 amplifier with an electret microphone on the input and a small TFT display.

 

I think the simplest and most accurate solution would be a frequency counter with a 1 second timebase and an audio amplified input.
There are lots of circuits on-line for getting a 1 second delay by counting down from a 1MHz crystal. Use that as the gate for a decade counter with digital display that has the guitar signal as an input. This solution would give accuracy to 1Hz and would work for tuning any string, with a simple note/frequency table.
Note: Without those restrictions, I would make a much simpler version, using a ATmega328 uC, a 386 amplifier with an electret microphone on the input and a small TFT display.

I suggested that as one choice back in post #7, but with the added function of display hold, because a guitar note does not last very long. The challenge then being that a regular counter scheme dooes not provide the three decimal point resolution given in the note versus frequency tables. So the question becomes how close is "close enough" ??? I really don't know.