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DX-style Operator (Thru-Zero FM/PM oscillator - FM Ogre)
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3 ... 30, 31, 32  Next [all]
Author DX-style Operator (Thru-Zero FM/PM oscillator - FM Ogre)
wsy
So, I really wanted some thru-zero action for my MU rack. Not just "thru zero" - but
those wonderful clangorous tones that the old Yamaha synths used to make with
FMing sine waves (well, FM/PM, but you get my point). Heck, they didn't even
call them oscillators, because they did much more- they called them "operators". And
all they had were sines and it was old and grungy and digital and beautiful and like
nothing ever heard before.

And I wanted it for my modular.

And now it works.

It all fits on a DSP PIC chip. Software, of course, but it actually does quite a bit
better than what the Yamaha could ever do.

I even made a video:



The best part: the chip costs under $6 in onesies! Another three or four
bucks worth of parts are needed (opamps, a voltage regulator, a 10MHz
crystal, three caps and a resistor.)

Whaddya all think? :-) Time to make some percussion?

(oh- and I had the LED in the wrong hole for demoing phasemod thruzero in the
video; it was reading out FM negative frequency. I also got hard synch in and
out going now.

I think I need to make a PCB or find someone who can. smile

- Bill
bartleby
wow.

just wow.
infradead
holy awesome man.
Dego
Sweet, god job thumbs up
lordofthebored
SICK applause
diablojoy
pretty damn good thumbs up
A pcb for it looks like it would be fairly easy and small.
bartleby
let's eurorack that thang!
ABC
HELL YES
Blingley
diablojoy
euro would be nice but any board design should also allow for building in other formats too.
mckenic
Very cool!
decaying.sine
You could ask hexinverter to help lay out a PCB. He does them while sleeping I hear and even if he is hanging upside down!
kuxaan-sum
Nice job!
wsy
[quote=everybody]
[/quote]

Thanks! It took longer than I expected and there are still a few tradeoffs that
I'm not entirely happy with (i.e. real phase modulation is actually pretty noisy).
But it's there and working.

decaying.sine wrote:
You could ask hexinverter to help lay out a PCB. He does them while sleeping I hear and even if he is hanging upside down!


Hmmm... interesting. I've considered a "bespoken build" on this, and approached
a rather busy module producer already but maybe, just maybe
hexinverter could do it...

The schematic on the DSP end is dead simple. It's a 28-pin narrow DIP and I can
recite the pinout pretty much from memory:

Pin 1: MCLR* - wire it with 10K to V++.
Pins 2 thru 7: V/oct pitch, Distort, Linear FM, FM index, Linear PM, PM index
Pin 8: V--
Pin 9, & 10: 10 MHz crystal
Pin 11: unused
Pin 12: unused
Pin 13: V++
Pin 14: Heartbeat (1 flash /sec / MIP of headroom left in the DSP)
Pin 15: Negative frequency out
Pin 16: Negative phase out
Pin 17: Hard Sync out out
Pin 18: Hard Sync in (+5V tolerant)
Pin 19: V--
Pin 20: Vcap (1 uF from here to V--; for the 2.5 volt DSP core voltage stabilizer)
Pin 21: Program Data
Pin 22: Program Clock
Pins 23 & 24: + and - on Distort + FM channel
Pins 25 & 26: + and - on Distort + FM + Phase channel (yes, they're separate. Think "Chorus"
Pin 27: Analog V--
Pin 28: Analog V++

The only non-obvious stuff is that it'd be handy to lead the MCLR, V++ (+3.3V), V-- (gnd),
Program Data, and Program Clock to a 5-pin 0.1" header for in-circuit reprogramming, and put a 0.1u ceramic decoupling cap between 27/28 and 8/13 and 8/19, and maybe a
10-100 uF electrolytic on the +3.3v feeder.

If we could make it as a wire-to-me board, then the same board could work on
both MU/5u and Euro. Then either have a separate jack-and-pot board, or freewire
it in the style of DotCom and AC.

- Bill
frequencycentral
Very well done sir!
decaying.sine
If it is really that simple, I could try to do it for you in DipTrace. I have been working on learning that. Do you have a hand drawn schematic? I could probably draw one up with the basic information that you have.

That being said, Stacy could probably do that in a eye blink. He makes his own libraries and stuff too.
ashleym
Amazeballs.

It looks like only a few bits and pieces on the breadboard too. Easy easy easy.

Would there be a chance of other waves than sine?

Otherwise could we pitch Hex against Fonik and have a PCB make-up-face-off?

A preprogrammed PIC would help, when I attempted to blow a PIC for an Electric Druid circuit I ended up gazing at code, a programmer and a chip with nothing working. Brilliant stuff.
Microscopial
im in wohooooooo those sounds were sick applause applause applause
GrantB
Microscopial wrote:
im in wohooooooo those sounds were sick applause applause applause


+1 and that was just ONE operator!
sduck
Very nice! I'll take 2. Make sure you've got motm/MU/euro style power inlets on the board - I know thats possible. I'm guessing it all runs through a regulator so differing voltages won't be too much of a problem.
sempervirent
Sounds good, nice work. I like how every good analog design under the sun has been cloned, now we're down to cloning the digital stuff that killed off the analog stuff.
raisinbag
Man that sounds RFC!!!! I think if you want hex to do it you will have to fly to winterpeg and do his homework for him. I'm not good enough with dip trace to be useful yet, I am still working through tutorial. But I will certainly be down for some of these. Maybe enough to make an analog dx7. thumbs up

Edit: oops, I used the "a" word for a "d" word circuit. Please forgive.
wsy
sduck wrote:
Very nice! I'll take 2.


... but you need 4 to make a single DX-100 voice, and six to make a DX-7 voice!

(well, sorta..... having every operator have CV-able feedback/distortion control makes
some of those operators superfluous.)

sduck wrote:

Make sure you've got motm/MU/euro style power inlets on the board - I know thats possible. I'm guessing it all runs through a regulator so differing voltages won't be too much of a problem.


Actually, it's a little trickier than that.

The DSP is a 3.3 volt part - and that INCLUDES the built-in A/D and D/A converters that
I use to get the parts count down. So you need an on-board 3.3V regulator, either
powered from the +5 bus if you have one or the +12/+15 bus if you don't. But it
only needs like 40 mA so even a teensy regulator will work.

You have a shared ground, and you need to use translators to get the +/- 5 volt
or whatever swing into that 0 to 3.3 volt (fortunately, that's just one op-amp stage and
three resistors.) Also, you need a couple of diodes to protect against crazy
out-of-bounds voltages from blowing up the DSP.

Then what comes out the back of the DSP is also in that 0 to +3.3 range, and you need to
expand that back to +/- 5 volts. That's a little tricker; I *CAN* do it with two op
amp stages but I want to kick around and do it with just one.

But you still need 6 + 4 stages of op-amp to do it, and yes, it will fit on a fits-anywhere
card, but it's a little tight unless you use SMT.

Actually, the biggest thing you need is EGs One for each operator in the chain, then
one for the final envelope. Seriously. That's why I put FM Index and PM Index on
their own analog input pins, so you can plug in the EG of your choice.

- Bill
diablojoy
Quote:
Maybe enough to make an analog dx7.

hmm need 6 digital operators to start with, would be pretty orsm .
diablojoy
Quote:
Actually, it's a little trickier than that.

The DSP is a 3.3 volt part - and that INCLUDES the built-in A/D and D/A converters that
I use to get the parts count down. So you need an on-board 3.3V regulator, either
powered from the +5 bus if you have one or the +12/+15 bus if you don't. But it
only needs like 40 mA so even a teensy regulator will work.

You have a shared ground, and you need to use translators to get the +/- 5 volt
or whatever swing into that 0 to 3.3 volt (fortunately, that's just one op-amp stage and
three resistors.) Also, you need a couple of diodes to protect against crazy
out-of-bounds voltages from blowing up the DSP.

Then what comes out the back of the DSP is also in that 0 to +3.3 range, and you need to
expand that back to +/- 5 volts. That's a little tricker; I *CAN* do it with two op
amp stages but I want to kick around and do it with just one.

But you still need 6 + 4 stages of op-amp to do it, and yes, it will fit on a fits-anywhere
card, but it's a little tight unless you use SMT.

Actually, the biggest thing you need is EGs One for each operator in the chain, then
one for the final envelope. Seriously. That's why I put FM Index and PM Index on
their own analog input pins, so you can plug in the EG of your choice

hmm at first glance 3 x opamp packages plus PIC plus regulation and input protection
100 x 50mm brains board plus a panel control board double stacked
plug in style should be doable without resorting to SMT i would think.
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