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Project Help and Ideas » home made tuner

July 04, 2009
by sgmaniac1255
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On my way home i was thinking of some ideas to try out on this wonderful piece of plastic and the i got to thinking about what i love to do and what i could to improve on it.

and the idea for a tuner for my trombone came to mind.

in my design I'm thinking of ditching the LCD Screen for an LED output in a seven step tuning display(Green being the right Frequency for the note of course)

R = Red Y = Yellow G = Green

R R Y G Y R R

i still need to work out the Note frequencies, i know that the my band's standard for A4 is now 442, and that every octave doubles... wikipedia may become my best friend

Their formula for defining frequency of notes... where "n" is the number of Half-steps from my note and A4 (442Hz)

f = 2^(n/12) × 442 Hz

also i was thinking of using the Dip switches to "dial" in the note i want to tune using 4 bits to represent the 12 different notes in an octave (0000 = A, 0001 = A#, 0010 = B... so on and so on ...1010 = G#)

then i was going to borrow out of the Piezoelectric Sound Meter project for the tuning "pick up".... (after i even begin to understand the stuff they talked about in the video.... right now its like the space shuttle its so far over my head ;)...)

nothing is started yet, but it will be soon, I'm going to have to get some LEDs and Probably resistors to go along with them, but that's no big deal

The hardest part that i can foresee is going to be figuring out how to read the Frequency of the note coming in from the piezoelectric buzzer

ill probably, Time permitting, start building next week

July 04, 2009
by mcai8sh4
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Nice idea, once you have the 'reading in of the frequency' sorted, the rest should be relatively straight forward.

You could keep the LCD (useful initially for debugging) so show what readings your getting and displaying the note you're closest to, then you wouldn't have to 'dial' in your target.

I look forward to seeing the progress on this one - keep us all posted!

July 04, 2009
by sgmaniac1255
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well, the whole idea of removing the LCD was to free up room on the board and pins on the MCU, but looking at it now, i might be able to get away with keeping it Pin wise... but i don't think I'm going to have room on one Breadboard, i might have to upgrade... or make a more permanent structure

July 04, 2009
by mcai8sh4
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You should be able to keep it in - you only need 7 pins for the LEDs (or less if you use some funky ideas - charlie pixeling poss)

I bought another solderless breadboard to make more room for my projects - Plus it means you can have 2 projects running at the same time with out altering your circuit too much

July 05, 2009
by sgmaniac1255
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for those who weren't there, we spent some time in the IRC channel (is that the right term?)brain storming about how to read a frequency input on the MCU.... (or more like mcai8sh4 and wayward brainstormed while i sat there and scratched my head about what they were talking about :)

anyway, their technical ramblings i think will help me to get started in the right direction, and i wanted to say thank you.

(plus i wanted to plug in the IRC too :D)

July 05, 2009
by mcai8sh4
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We were happy to try and help. it's quite an interesting project, and raises some interesting questions about how you can achieve your goal.

It was nice speaking with you, hope to see you there more often.

Also I hope all you American folks enjoyed your 4th celebrations yesterday!!

July 05, 2009
by sgmaniac1255
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i just had an idea! please correct me if i'm wrong

the signal coming from the piezoelectric buzzer would be, theoretically, a sine wave alternating voltage polarity right, (i'll test this when i get home and can toy with it) or at least pulsing from a high to a low, would a diode eliminate the reverse(?) signal and turn it into a square like wave?

if that works, then it would be just a matter of timing how long the pin is "on" and then comparing that to the Half-Period of the note im trying to tune

this way, i wouldn't have to worry about the ADC... i think, but use the actual driving voltage from the buzzer and amplifier (if needed)

July 05, 2009
by sgmaniac1255
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come to think of it, i remember reading at howstuffworks.com that's how Amplitude Modulation (AM) Radios work, they eliminate the underside of the Sine wave with a diode then amplify and send straight to the speakers.... more or less

July 14, 2009
by sgmaniac1255
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here is the layout of Version 1.0 of my project (no hardware made yet, I'll get to that when i figure out the math behind the amplifier, calculus is a bit over my head right now)

Tuner V1.0

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