Advanced PWM

[BobF]

BobsAdvancedPWM.fsm

(230.94 KiB) Downloaded 1157 times

Hello gang,

This is just another Pule Width Modulator. Pretty simple if you look at the insides, but it does have some nice features.
For one it can be easily modulated and has a slew limiter added for addition timbre. This would really be a nice addition for someone building a complete synthesizer or effects box.
Anyway have fun! Later then, BobF.....

P.S., If you do use this in your own projects or have any mods, and so on, do please let us all see them!

[tulamide]

Hey Bob,

I like it. I never looked at pwm examples before, because I expected to not understand the inner workings. Since you did this one with a lot of stock modules, I can follow the concept pretty easy!

There are just two things, I don't understand:

What is the second osc for? I can just remove it and get the same results. And if I don't remove it but raise the volume, the sound becomes less usable (musically speaking).

The slew limiter seems to dampen the transitions, basically converting the combined signal back into a sine? What irritates me is that it also has influence on the output power. Could that be automatically compensated? So that, for example, a signal with the limiter set to half would be just as loud as one without limiting?
EDIT: Maybe I should better say: just the same amplitude peak?

(How I love that some guys of/over my age are here, that finally show me how all of the synths of the late 70's/early 80's worked, that I used so excessively to make music. I sometimes miss the ease of use of synths like the Alpha Juno, which btw. still is a fine synth for EDM/Techno/Trance )

[BobF]

Hello tulamide (really glad you liked it) and all others. Sorry, I really need to start commenting my schematics. The second osc is there ONLY to show that either a LFO or standard VCO (Osc) can be used for modulation. I used to teach a electronic music class at a local college many moons ago. I found out real fast if you did not tell students, like in this schematic as an example, that you could use all kinds of sound producing modules for modulation or what ever, they would just use one. They would modulate a vcf or vco with a lfo, but would never try modulating a vco say with another vco and etc., they just kept using the lfo.

As for automatic compensation of the power, a better mind than mine need try. Does anyone out there want to take this on?

Enjoy! Till next time, good byee. BobF....

P.S., As always any comments, mods, or improvements, are always welcome.

[BobF]

BobsAdvancedPWMwAGC.fsm

(245.54 KiB) Downloaded 1106 times

Hello tulamide and all others,

Ok, here is the best fix I can do for power loss in the slew limiter. I added a AGC to the output created by MyCo ( many thanks MyCo). This is still NOT perfect, because I also dropped the gain a little on the slew limiter knob, but it is still pretty darn good. If anyone has a better idea, please do let us all know about it.

Later then, BobF.....