OSKITONE OKAY 2 Synth, Assembly Manual

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555_4040 0.1.1
The 555_4040 board uses two ICs:
1.
LM555: ​ timer wired as an astable mutlivabratory
(oscillator)
2.
CD4040: ​ ripple-carry binary counter/divider (frequency
divider)
The 555 (IC1) is the heart of the OKAY. It oscillates at a
frequency determined by R1, R2, and C1. Its output is piped to
the input of the 4040 (IC2), where it’s divided 12 times to
make 12 different octaves.
The 12 octaves are exposed on the right side of the board,
grouped in halves from 1-6 and 7-12. The raw output of the
555 (octave 0) is accessible by the unlabeled, single header
pin to the bottom right of IC1.
Name Value Explanation
C1 10nF (103) Sets oscillator frequency on IC1
C2 10nF (103) Ties “Control voltage” IC pin on IC1 to
stable power, minimizing spurious
noise
C3 .1uF (104) Bypass capacitor for IC1
C4 .1uF (104) Bypass capacitor for IC2
R1 1k (brown
black red) Sets oscillator frequency
R2 N/A This connects to SPST_VR PCB
IC1 LM555 Timer IC chip, in socket