Hi, I've decided I'd like to design and build an analog guitar tuner. I've had two classes in electronics but I've never done anything real. Just on paper. So I really know nothing I guess, compared to you guys.

I don't want to cheat and look online? I used to do a lot of programming and it was so easy to do your own little programming projects, stealing other peoples code never felt like "cheating" but with electronics it seems different. I don't know how to the walk the line between designing it all on my own and getting resources off the internet. Luckily I haven't seen much about fully analog guitar tuners so it seemed like a fun project that might actually be difficult to "cheat".

Anyway, any recommendations on how one starts a design project like this? I've learned about filters (passive) in class, as well as a few different types of oscillators. I guess it'd be easier to tinker if I actually had real parts and tools?

The nice thing is I guess I'd just have to do it for one string, then multiply the design by 6. Six for the price of one Thanks

 

This is a classic class assignment so I cannot give you answers.
Also there are more than one ways to skin a cat.

Firstly, you have to take it in context of the course.
Is this supposed to be an exercise in analog, digital or computer electronics?

Having determined that your next step is to identify and define the problem.
I will go so far as identifying the problem as being: How to build a frequency meter?

You take it from there.

 

Oh neat, I didn't know this is considered a classic thing. This isn't for a class I can assure you of that. Definitely not trying to cheat. Just something I decided I could do on my own.

I'd like to do this all analog, op amps, transistors, and various passive components. Just because that seems the most fun to me at this stage.

My initial thoughts are to use three filters, a LPF and BPF and HPF, and three LED's, one indicating flat, one indicating "in tune", and one indicating sharp.

Connected to each of these LED's would be a corresponding LPF, BPF, and HPF

Then i'd have a toggle switch which would select the string I want to tune (and hence the corresponding target frequency and filter parameters)

The problem is, doing it this way would require a total of 18 passive filters, and feels like brute forcing it.

Ultimately I'd like it to fit it into an altoids can, with enough room for a few mints.

Also, I like the idea that this project is easily "add-on-able". For example, it would be great if I could alter the design in the future so that no switch indicating desired string to tune had to be selected and that it would "guess". I think this would be way beyond my abilities to do though, at least analog only

 

Even though is may not be homework for you, I cannot provide full answers because this could be homework for others.

Bandpass filters will not work because the filter would require extremely large Q and would require too many circuits for six notes.

I suggest you work on the concept of a frequency meter.
Another idea you can look into is called a phase detector or a phase-looked loop.

 

Even though is may not be homework for you, I cannot provide full answers because this could be homework for others.

Bandpass filters will not work because the filter would require extremely large Q and would require too many circuits for six notes.

I suggest you work on the concept of a frequency meter.
Another idea you can look into is called a phase detector or a phase-looked loop.

Thanks for your help.
Will read up on both of those.

Wish I went to school somewhere where this was a homework problem. I've taken both of my schools undergraduate level electronics classes and never got to do anything cool like this.