[sdiy] sn76477 external control

[René Schmitz]

At 16:28 29.05.02 +0200, Rude 66 wrote:
>that may be wordt a try if it doesn't destroy the synth.could it?
>
> the half octave range (and playing backwards,remember..) doesn't bother me
>too much because it's basically a noise box, and i can always sample a sound
>and then play it. it's not my only synth.. though 1 or 2 octaves would be
>cool. but it has 3 switches controlling range (sort of 'lo, mid, hi') so in
>reality the problem is probably there, as in the cv-in only controls the
>selected range, not the whole possible range. i've tried selecting all 3
>together, but that doesn't make it better either..;-)
>
>r./

Although I've never actually tried this:

I think that the timing resistors could be replaced by standard current
sinking 
expo convertors. Somewhere I've read that these timing pins are held to 3V 
internally. This seems to suggest that they actually sense the current. 
This would not require to power the chip from 0/-15V, as the 76477 has 
the timing Rs to GND and not V+ like the 566. 

Cheers,
 René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159