Ok, well it seems to working as expected. I have the /WR fed by a 555 with HPF and schmitt for the short pulses. I wanted to use the LM331, but it isn't doing what I expected. I assumed it would be a supply voltage level square wave, but i'm getting like a 100mv fuzzy wave whose amplitude changes over the range too :/ . Not very good, I don't think its right at all since it says "logic output".
Anyhow, it does work with the 555 system. It goes a bit haywire every so often, I think it starts picking up mains radiation since I have a long wire from the pulses source to the ADC as they are on seperate breadboards. At least I hope thats all it is, it goes back to normal when switched off then on. Perhaps /INTR should go somewhere even with /WR fed by a seperate source?
Removing the LSBs does quite little, so I remove the ones from the 250k upwards. That gives the effect I expected/wanted more. Just need to do it with the logic switched instead of pulling wires out
.
I have attached a short demo (I hope it's ok to do this, its well under the limit?). This would work much better MIDI controlled, so an accurate sample rate can be moved directly to, rather than sweeping to it via a pot (currently a trimmer!) and guessing the pitches. First you hear bit rates changing in drums, then bit depth in drums, then some bit rate with a keyboard (needs to be midi controlled for this in particular). Only have any hope of getting MIDI control if I can get that LM331 working (then use MIDI-CV convertor). Anyone used one before? Thanks for the help with this people, I probably will build it into a unit, though it isn't quite the tone I wanted
EDIT - Ok, it won't attach.
Hmm, a nice idea here. Mabye I could use the audio out of a keyboard, clip it into a square wave and put it through the pulse generator. Then you could just play the decimator with the normal audio out of the keyboard