I've been thinking a bit about the UI lately, and especially how to control the LED dials. I've previously found some nice constant current LED driver mux'es. They have 16 channels, which I can use to multiplex the (up to) 31 diodes of a led dial.
But 16 channels may be split into 8 x 8 = 64 channels, meaning I can drive at least TWO dials from a single controller.
Thus, I went back to see if I could group dials a bit smarter so I can put two and two dials on a PCB with one shared multiplexer. Also, it would be cool if I could make "modules" for the UI so I can make multiple copies of various boards, which is significantly cheaper than one-offs.
Here is a restructuring of the left hand side, this made me rethink the structure and ended up actually solving some issues I had with the natural flow - now I have sources top/left, then the source mixer and finally fx. Much better.
 |
| Before restructuring |
 |
| After restructuring - now fx pots align vertically, and LFO stuff aligns with clock/arp. I've also managed to squeeze in an additional LFO pot and some buttons, and replaced the LFO selector switches and made a better (two sided) shape selector. |
As for other modules: I will try to make a PCB that can work with both DCO/VCOs and Filters, though the SVF slope selector is a bit of an unsolved case:
 |
| I will probably replace the Ext CV/Wheel/LFO/Kbd buttons with pots, and space them the same as for the filters |
 |
| I will have to change the size of the top pots to match the oscillators. The Slope selector is a bit anoying, perhaps I can make boards that break apart making it possible to remove the selector bit |
The envelopes are of course identical, except for an additional button on Env 3:
Also, the output mixer and pan/fx send modules are similar and could maybe even use the dual led rings from the source mixer/left side
There are still quite a few special modules, like everything in the lower part of the screen, but every little simplification helps!
 |
| Latest version of the front panel |
Hmm... how many leds per dial? I would not go too high, 8 seem enough or maybe even 5. That would really reduce parts.
ReplyDeleteThe number of leds per dial depends on the size of the pot. For the smallest one it's currently 19, the medium is 31.
DeleteI do agree that a smaller number would be more price effective, but one major motivation for making the synth in the first place was using endless pots and high resolution led dials. The leds in themselves are of course dirt cheap but the number of mux'es needed is high, I do agree there. However, as the leds must be mounted closer to the panel than the pots, I will have them on a separate PCB, and combining two and two seems like a nice compromise.
Had this been a production model I'm sure I would have chosen a much smaller number. 15 seems to be the sweet spot (That's what the Moog Little Phatty and Nord Lead 3 uses for example).