Tuner time!

[Chris60601]

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[Jopn]

Tuners are difficult not because of small SMD parts (which often have through hole equivalents we can use), but because they require digital programming.  They have to take the input, strip out all the overtones, then compare it against various frequencies to decide the closest note.  Then output the discrepancy in some readable form, etc, etc.

I'm not sure what the schematic you posted does exactly.  It has a 6 way switch that looks like it controls what note the 555 chip is generating.  Each point of that switch has a pot, might be a trim pot for adjusting the tuning.  There's an LED driver as well.  But I don't see how this would actually compare the input to the sine waves generated by the 555.  There's a speaker in the schematic as well, so maybe it's just meant to be a tone generator, like an electronic pitch pipe?  But then what's the 8 LED bar for?

[ξεναγος νεκροπολης]

yeap...i agry with you jopn...
it must be a tone generator.

chris
the trimmers seems to have to be pre-tuned and then with the 6way switch you can choose which note you want to hear and then tune your guitar.

this reminded me an other project i did

http://www.paulinthelab.com/2014/06/ellas-stylophone-stripboard-layout.html#comment-form

you can take the same thing out of this stylophone with some small mods.
take the stylus wire through the 6 way switch, then to the "keyboard wires"
and you can choose what note you want to hear!
i'm sure it will do the job.
i've build this stylophone and it's great.
plus it needs just two 555 ics and there is already in vero!