OK, I need some eyes (@fredrik? Anyone?) on a schematic and a breadboard because I obviously am doing something stupid and am utterly unable to find it.
I have this
on a breadboard:
The schematic’s pretty much the datasheet, with some unused functions unconnected: Only a single CV, no HF track, and no sync inputs. But ±12 V instead of ±15 V, and for R1 I have 680R instead of 620R and for R7 I have 330k instead of 360k because that’s what I have.
With the trim pot near center, when CV was 0 V I got 1.9 Hz on the outputs. And when CV was 12 V I get… 19.2 Hz. No, not kHz. Hz.
I cranked the trim pot up all the way and now I get:
|CV (V)||Freq (Hz)|
All component values have been checked two or three or more times, and before turning up the trim pot I took out the 3340 and measured 29k from pin 1 to -12V, 6.3k from pin 2 to -12V. I also tried a different 3340, same result.
I can’t see any mistakes on the breadboard, and I can’t see any differences with the datasheet circuit other than those noted above.
So what’s wrong?