FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 

New Frac Items...
MUFF WIGGLER Forum Index -> Fractional Rack Modules Goto page Previous  1, 2, 3, 4, 5, 6, 7 [all]
Author New Frac Items...
really nice looking panel. long live frac!

The programmer for the programmable logic ICs arrived today. Just need to get some of the chips. We laid out a little breakout PCB that will contain the CPLD and programming header. This will piggy-back onto the main board, which will have all of the analog circuitry. I'm thinking this will make a good first project, since it uses a lot of simple logic functions, but a bunch of them strung together in a configurable way.

Will update soon!
I really like the arrangement of the LEDs. It reminds me a little of the JAG.
This may be taking a slight turn. There was a recent thread about phase modulation and phase distortion oscillators. It kinda got me thinking about these.

So, I laid out a sawtooth core VCO, implemented a phase shift circuit, and am working on wavetable lookup right now. So I may put this, and all the BitBucket LFSR stuff into the same module. All of it is relatively simple stuff, and so far it's a very low parts count even with all these features. It think it would be fun to have all this digital stuff available in one module.

Anyway, most of the initial development is done. Just picking components, and then will lay out a prototype to test it all with sometime in the next week or two.

Kind of a "CZ Noise Ring City" sorta thing. hihi
Hmmm.. I'd think a dual CZ osc would be a module on its own.. Bit bucket is its own thing too..? But if there's some connection btwn the functionality that I'm missing, of course -you da man..
I wonder if the panel might get out of hand, if you put it all in one module.
I don't think it will be too crazy. The VCO portion is little more than a sawtooth core with a few basic VCO controls. Then there is a phase knob/CV. The lookup table is all internal. There would be a couple of outputs (digital waveform, one or two analog.)

The reason they're good together is that both can be clocked by the same core, all of the bit bucket functions are coming off of a single IC (CPLD) and the two digital outputs can be combined in interesting ways via logic functions using a few panel buttons or switches.

They don't necessarily HAVE to be combined, but there is a lot of duplicated circuitry between the two that could be consolidated into one device.

As far as the second VCO in the CZ config for sync, phase, etc. this could be any external VCO. (though really with the simplicity of the current saw core, it could be on the same PCB too without a problem.)

Anyway, I've got all of the component parts figured out, and am just working on the ROM and conversion portions of the VCO parts, and have just started working on the logic for the CPLD for the BitBuckety parts.

They could easily be mixed and matched or separated out in any proportions.
I decided to keep these two items separate. hihi Mainly because I thought of a lot more that I want the PD oscillator to do, and since it will be a mostly analog implementation, it's going to take some PCB space.

Just placed an order for the CPLD breakout board, and am continuing to work on the logic.

In the meantime, I posted the following over in the DIY forum. If anyone is inclined, here's a schematic I whipped up last night that could be fun.

Pasting other thread here:

Couldn't sleep, so I whipped this one up. eek!

This one is an 8 bit register made up of CD4013 D-Type flip flops. It also has a 1V/Oct VCO for the clock (Triangle and Square outs are available for normalish VCO use.) There is an R/2R to create stepped voltages, that is then scaled through a VCA. There is a differential amplifier off of the both the serial output of the register, and it can be switched to the output of the LFSR-Loop. There is an external data comparator input. So data either comes in there, or is generated by the feedback loop. There is a bank of four switches to route the bits through the XORs. I tested quite a few configurations. Lot's of tones/patterns available there. (See PDF for better view)

My CPLD breakout boards arrive later this week. Once I have those, I'll be able to start getting familiar with programmable logic properly. I've got some schematics drawn up in the dev environment to try out. I don't think it will take long to get the hang of it. We're getting closer hyper

In the meantime, I've been working on some buffering and scaling for the CPLD IO pins to interface with the outside world.

More on this soon!
Also here's a Frac/Euro friendly Phase Modulation VCO I whipped up last night, while I'm battling with my Phase Distortion and ThruZero design. I order prototypes that will be here next week. If everything checks out, this will be available shortly. PCB is 4"x4" so the panel will need to be a bit bigger. It will have plenty of controls and IO though to utilize the space.

While I wait for CPLD ICs to show up, I made one last CMOS version of the BitBucket thing. PCBs will be to me by next week, and I'd be happy to do a short run of them while working on the more fully featured version. It's really not much more or less than a NoiseRing, but for anyone that needs this functionality and can't get it for Frac, it may be useful.

It has a maximal linear feedback loop like the NoiseRing, but can switch to external data only, or just sampling white noise, or just using the ring. It has a bipolar output for doing digital noise, a serial output that can be used to feed other data circuits, or modify the data stream and feed it back into the input, (or use as random gates.)

There is an LED for each stage of the shift register.

There is also a CV output for random voltages.

It's externally clocked on this version, so clocking with a V/Oct VCO will give you tones in certain modes, or being fed certain types of data.

The extended version using the CPLD will have longer shift register, movable taps, configurable XORs, onboard VCO, more logic gates, etc. etc.

Anyway, I'll have this one tested next week, and will talk to the distributors about carrying a few of them. Assuming the prototype PCBs work fine, I could also send a few of those out in the meantime.

I'd put the extended version out a couple of months, so this may be useful to some.

Got the Bit Station boards back today. I'll get one built up and tested after work today, and post some updates.
Would love a blue banana frack Bit Station!!! . .

keep up the good work!

I tested it last night, and other than needing to tweak the reference voltage for the comparator slightly, it's working perfectly. As it is right now, it has fairly similar function to the Noise Ring, but it's a little more flexible in some ways, and a little more simplistic in others. A VCA to scale the CV output would be nice, as well as an XOR separate from the internal LFSR chain. It's been a lot of fun so far. Anyway, I'll figure out the right voltage for the comparator tonight (one resistor value change) and then it's pretty much ready to go. Still working on the more complex one, but it will be a little further out. I could create a stackable companion board for this that would contain XOR, VCA, V/Oct Clock, and maybe a simple slew or integrator. That might be kind of nice, and would be relatively easy to whip up. (I already have the functions laying around, so it would just be board layout work.)

It's nice being able to see the entire shift register contents. Maybe I'll upload a quick/tiny video of this in a bit. It's a bad phone vid, but will show the indication well enough.
Ok, horrible video, but it shows a basic CV-Out patch, and the indication.


thumbs up

(testing the Bit Station and Four Pole VCF) My test builds are 5U, but the boards are very 3U compatible. I just have one more tweak to make on the filter, and both of these should be ready to make some more PCBs.


Here's the filter PCB. It's SMT, but was pretty easy to build by hand. I settled on Polypropylene capacitors. They seemed to have the best overall sound.

MUFF WIGGLER Forum Index -> Fractional Rack Modules Goto page Previous  1, 2, 3, 4, 5, 6, 7 [all]
Page 7 of 7
Powered by phpBB © phpBB Group