FPGA Oscillator

This has turned up from WaveShare. It is really very reasonable as I don't think that I can buy the FPGA device for that. I plan to bash out a something themed on the ShapeShifter. It won't be as sophisticated (or any where near as expensive). I always enjoyed a bit of VHDL coding but the requirement for it is sadly thin on the ground these days. I was a bit surprised that Cyclonix really just bolt an Altera evaluation board onto a bunch of DAC/ADC and analog interface device on a panel. From the reading I have done, they use the NIOS soft processor -- I was going to skip that bit and stick an ARM in beside the FPGA as the compiler/debugging is generally a bit ropey on an environment with such a small user base. That will leave more space for Audio processing and waste less resources on the FPGA.

From the Verge

When Walking to work recently I discovered quite a nice Audio Generator in the yearly rubbish collection beside the reoad. I had to replace a binding post and put a new power plug on it but it seems to work nicely enough...

Later in the week I found a fairly old Yamaha Electone B-4BR. So as not incur the wrath of the wife it mostly stayed there except for the reveb spring...

Analog CRO #3

With the passing of the Dick Smith CRO and the unsuccessful resurrection of another CRO that I rescued out of the work skip I have moved on to an LG CRO!

0.8mm Vs 0.5mm

Have been designing some PCB's that I am going to have to get made... This is beyond the Press'n'Peel limitations... I am trying to make it compliant with DIY but there are going to have to be surface mount parts as the processors just aren't available in through hole. I suspect that it will still put people off but... I must admit that looking at some peoples handy work I am still amazed at how bad some of it is! On the flip side some of it is totally amazingly neat need as well... Looking at only using parts in 32pin QFP and 44pin QFP -- these are the only parts that have a 0.8mm spacing instead of the more common 0.5mm spacing. I have sort of got use to the higher density but I can see how it is a bridge too far for some people... There are significantly less parts available in those packages and perhaps more importantly significantly less on-chip-memory... This is a bit strange since the actual package size is still the same as 48pin/0.5mm QFP which seems to have truck loads of RAM... oh well we will see where this leads us...

Halvosen Attractor

Onwards and upwards... Whilst eating my sandwich at lunch yesterday I was reading about other Attractors and came across a lot of references to Sprott's Chaos and Time-Series Analysis book. Having the advantage of a child at University I e-mailed him and he borrowed it from the library. Probably a few orders of magnitude over my head for most of it, it did clear up the differences between flows and maps (which is obvious after the fact) and has a fantastic appendix full of different formula for common chaotic systems.

I have added quite a few to the formally called Peaks board and code stream. The one I like the best is the Halvosen Attractor which, for quite a simple formula, has a bizarre thrashing around like a cat in small cage! Here is a quick photo from my least favorite CRO (since the Dick Smith one seems to have died from dry electrolytics)...

Rossler Barrow

Well made even more hatchet work on the code... Have been building for both Keil & IAR as developing on two compilers does sometimes show up issues in the code and how the different compilers work. I made a FixedPoint class to make the code a bit less messy and hopefully it will also support seamlessly moving to a floating point compliant processor... It did show up a few things that had me scratching my head a little bit. Oliver's code has some casting that I thought should have been unnecessary... When I implemented the class I found that it wasn't just the multiplies that needed to be 64bit and that the compiler was smart enough to keep some of the other maths at 64bit to stop wrapping... FixedPoint class got more complex... Anyway all works nicely now and have thrown a few extra chaos modes into the mix... This being the Rössler attractor:

Lorenz Barrow

Well stuff is happening now! The Peaks code is starting to bear little resemblance to the original but that is what open sauce is all about I suppose -- different processor, different compiler, same language and core... Lissajous figures always look the best on an Analog CRO so I dragged out my Laboratory Oscilloscope that I got while at WAIT and had some fun with the Lorenz generator that was actually from Streams originally. I have a few more  Chaotic generators to try...

Barrelling along...

Well not the fastest progress but:

Display Options...

Been looking at some display options for an old friend...

Evolution: Triangle VCO

This shows the progress of the Ian Fritz Triangle VCO that I talked about in an earlier post. After a few stuff ups it all came to life today! Two problems cancelled each other out which caused a bit of head scratching but after a few tweeks we did get this:

I haven't calibrated the 1V/octave bit yet but so far it seems really quite good! But then you would expect that from Ian's designs...

Wheel Barrow Walk...

OK as per a post a bit of a while ago (Imutable...) I have actually finished the prototype PCB for the mutant Peaks style board. Will try and etch it in the next day or so and do some testing. The name follows on from the Drowning by Numbers association. Since this one is using a fairly slow processor I thought that having Walk in the name seemed appropriate! I have probably gone a bit over the top with the heat-sinks. If people are happy to etch their own boards then this should be about a $30 build + panel & knobs... It is really only useful as LFO/Envelope Generator, not drums, but hopefully a useful learning/experimentation platform...

The Nyman album for the soundtrack to  Drowning by Numbers is one of my favorites and gets regularly listened to even though I bought it in 1991.

AD538

Got one of these to make a MoTM-510. God knows what it will sound like!

Elvis's Coffin

Busy weekend making a cabinet. Just cheap MDF then I thought of using some Tolex in a sort of ARP2600 sort of way... This isn't actually Tolex just some vinyl that is usually used for upholstering. The black looked a bit boring so I got some white instead. My wife informed me that it looked like something of Elvis's... the boys thought maybe his coffin... If all goes to plan I will need 6 of these just to use up all the boards that I have floating around...

Ian Fritz's Triangle VCO

I built Ian Fritz's Teezer VCO recently and it is extremely clever. It is probably the most unique design that I have seen for an Synth widget for a long time. I can see why he got grumpy when Mr. Blue Lantern allegedly ripped of his design. Anyway it piqued my interest in some of his other VCO designs on his website -- I know that I have looked at this one before, as it is dated 15 years ago, but for some reason I never really took it in. So I have done a layout that is P'n'P compliant and will give it a go.

Forbin Digal LFO

Well revisited the Digital LFO from many years ago. This is a Altium layout that I did about 3 years ago to replace the Eagle layout that was posted about 6 years ago! Unfortunately we had a failure with the Kinsten photo PCB... I typed the name wrong anyway... Grrrrrrr......

Ripplez

Well the huge, through hole version of Mutable Instruments Ripples is on a panel, and mostly working... couple of wrong value resistors that need replacing and maybe lower gain (i.e. specified -- not what's on hand) transistors...

Imutable...

Have been doing some new panels! And a new layout! Since I decided that 22 VCF's wasn't enough I have done a layout for Oliver's VCF, the Ripples... Now all I need to find is the developer and I could have got a bit further this evening.... grrrrrrr....

I have also done a different Mutable Instruments module in a version of Peaks. I wasn't so keen on the button interface to select the mode and have done it with a gold old fashioned rotary switch. Nice and tactile in  Chicken Head knobs. I plan to do some Chaos generation with this module as well...

Old Friend...

Dragged this old friend out of the large box of unfinished PCB's... This is from the Source of Uncertainty and this board is the part of that beast that was the inspiration for the Wogglebug. It ran out of steam a bit when I needed to make a digital noise source for it... While rummaging through the rest of the box I came across the Thomas Henry Voltage Controlled Noise Source and thought... lets make a bastard child from these!! Stay posted as I really want to finish this one off soon...

Hammond Scanner

I have been reading some interesting things about the rather freaky Hammond Scanner which was for production of vibrato on the Hammond Tone Wheel organs of the 50's & 60's. There is an excellent overview on the ModularSynthesis website. Whilst making one of those is reasonably impractical, despite having a lathe in the shed, I was also interested in the late Jurgen Haible's take on the idea here. I have done a bit of simulation of the important delay line and was also read some more from the ElectricDruid. Tom Wiltshire (the Electric Druid) suggests using all-pass phase shifters in Jurgen's design, this avoids the inductors which are expensive/bulky/prone to electrical pickup. In reality the Inductors look like the way to go. Simulation of all-pass filters shows quite a different response and the inductors aren't too onerous. I am thinking that the way to go with this is to build a board that has Jurgen's delay line but grafts on Oliver Gillets Frames style VCA's under Microprocessor control... It would work out to 4 off 2164 quad VCA's a couple of octal DAC's and a micro controller. Should be able to jam it all onto a Euro sized board as well for a laugh... May mock up a PCB and see how feasible it is...