...quoting myself..."The oscillator I was thinking of is in the Off-Topic section, "A Useful General Purpose Oscillator.". It perhaps could do with some simplification...skip ahead to the last few posts..."
I have already done some simplification a while back, I just haven't posted it yet. I'll review, maybe simplify further and update...
Steve A.
However, it's already simpler than the 'kit' version in this thread, it only uses a 14-pin micro instead of 40-pins, generates sine, triangle and square (logic) signals, and covers from below 1Hz up to 12.5MHz. But it doesn't have the display and isn't stand-alone, it requires (usually) a PC to control it. As ever, a compromise. The D-A is also 10-bit rather than 8.
It could be made stand-alone, but with wanting to automate frequently mundane tasks it would need some form of programmability, the old PC comes to the rescue again! Mundane tasks...frequency response of filters done manually is somewhat of a pain. It's much nicer to push a 'GO' button and watch the results...though it would need a companion unit to take the measurement(s) and report the findings...though the two could be built as a single instrument.
It all depends on your requirements, for just NBTV it's probably overkill, but I have other uses for it.
I did post a photo of the prototype oscillator part on Sep 22, 2020, but here it is again...it's not quite as complex as the circuit may seem...it also includes the regulator...where has the past year (almost) gone?
Anyway, again I'm digressing...any update on this will be in the correct 'Off-Topic' thread mentioned above...but, while I'm here, I might point out that a 74HC540 is fitted as a TTL output chip, I'll be replacing it with a 74AC540 for faster rising/falling edges on the TTL/logic outputs.