>On 10th July Mike Watson described (from memory I think?) a PIC based tuner
>which was published in the Picstart Design Contest Application Brief
>Notebook.
..chop..
>The cathodes of the LED
>display are connected to the pins of port C, which has been configured as an
>output only port. Each cathode is sequentially switched to ground for a
>period of time equal to one-eighth of the desired fundamental period. Thus,
>each LED is capable of being lit only once during each cycle of the
>synthesized frequency. Because an LED will be lit only if the

                   >amplified and clipped

>gating signal originating at the guitar is high, when the LED's
>cathode is at ground, the pattern on the eight LEDs will appear stationary
>only when the frequency of the gating signal (or one of it's harmonics) is
>equal to the synthesized frequency.

If one were to use an analog signal, rather than digital, amplified and clipped,
audio on the LED array anodes, the fundamental frequency would be the brightest
pattern, and harmonics would show up dimmer. This could speed the tuning
process and give more information about any signal analyzed with this
stroboscope.