Need some help with the kosmo vco w/ tuner. Please! I’ve lost weeks

One more thing to note is that with the typical resistor/capacitor values, the 3340 is calibrated to behave nicely from ~1 Hz all the way to 20 kHz and beyond, and you have to feed in quite a bit of voltage to get an audible signal.

Assuming nominal resistor/capacitor values, the 10k tracking pot set to the middle position, and that I didn’t completely screw up my algebra, the CV for a given frequency is:

cv = 1.463 * ln(freq) + 0.239

so for e.g. 440 Hz you need to feed in just over 9 V in total (coarse tune + CV).

The coarse tune on its own gives you a range of just under 1 Hz to 3100 Hz:

(note that the above equation isn’t exactly 1 V/octave, that’s what the tracking pot is there for)

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