And here’s the LMNC 3340 stripboard layout, with scribbles:

See here for the annotated Simple Low Pass Filter stripboard.

And here’s the LMNC 3340 stripboard layout, with scribbles:

See here for the annotated Simple Low Pass Filter stripboard.

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Copying over from elsewhere since it’s relevant to this thread:

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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Also some trouble-shooting tips, from here:

Turn the coarse tune knob. If it doesn’t change anything, check the wiring.

Measure the voltages going into the CV adder, via the 100k resistors at the top, marked with “CV” and “TUNE CV” here:

Annotated Simple 1V/Oct Oscillator Stripboard

Measure between ground and the top of the resistors, away from pin 15, and add the voltages. You need almost 5 V in total to reach audible frequencies, and about 9 V to hit A4 at 440 Hz.

Check the oscillator capacitor (the yellow one near the 3340).

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