• TechnoRobbo

    by Published on 02-16-2011 08:41 PM

    Original Post

    The Background Story
    Since I first posted this Project I have been working with JohnBF to allow this circuits to work with a wide base of microphones as well as electric guitars - the following circuits is the result of a series trials and reinventions.

    All timings are BS2 specific but can be modified - I've included my spreadsheet In case any of you want to modify it.

    The Circuit
    The circuit createsa super-amplified signalthat "clips" the wave into a square wave- the top and bottom half of 2 waves are summedand sent to the BS2 for meausring with the pulsin command. To compensate for piezo pickups, a 1 meg resistor was added to ground. The speed of the BS2 worked against us since it was crucial that the wavelength had to be measured as a whole and not 2 parts (high and low). I solved both those problems by adding a CD4017BE decade counter which summed the top half and bottom half of the wave. I also used the CD4017BE as a frequency divider allowing the BS2 to measure higher frequencies and lower freq's more accurately.

    JohnBF has been testing circuit mod after mod with me and is working on a propeller version using the same front end circuit.

    The Software
    The new code is faster and has excellent noise rejection. The code measuresa wavelengthand displays theNote and the Tuning Positionon the LEDs'. The LED's Decimal point denotes a Sharp. (Like any tuner it's best to use 12th fretHarmonics - the notes have less transients and are more stable.)

    The Parts List is a follows.

    2 -74HC595 Shift registers (Parallax)
    1 - CD4017BE [SIZE=4"]Decade Counter/Divider[/SIZE]
    1 - LM324 Quad Op Amp (Radio Shack)
    1 -7 Segment LED Number Block (Parallax)
    1 - 10 LED Bar Display (Radio Shack 276-081)
    18 - 1k Resistors
    2 - 1 Meg Resistor
    1- 470 Ohm Resistor
    1 - 1/4 inch Jack

    Have Fun


    Post Edited (TechnoRobbo) : 5/6/2007 7:00:38 AM GMT