I’m afraid the 8 Stage Quantizer & Sequencer production module would be outside the scope of a DIY project (which is why I didn’t make it one in the beginning.) But the core Amplitude Classifier design is worth doing. Maybe we can talk @pbalj into doing it.
WHOA, this is all coming back to me – I remember checking out the gamma circuit in the old Linear Technology Video Circuits document. Would the Gamma Shaper have been based on the LT1230, like in the notes? I think I might even have a few of those around here somewhere.
The pre-cadet world was truly the dark-ages of DIY video. I can’t thank you enough, really. I was trying to make all this stuff on proto-board and failing.
My gamma circuit (as implemented in Shapechanger) uses two LT1256. One as a power of 2 multiplier (expo curve), and the other to crossfade between expo and log curves. Log curve is created by subtracting the expo curve from the input signal at a gain of 2X (using an opamp.) This design allows for a mathematically accurate sweep (with video rate CV) between expo, linear, and log curves. This architecture would likely fit into a Cadet module, but there are other ways to do it as well.
Those chips are endlessly useful.
Yes, and especially for DIY/through hole designs, make multipliers and VCAs very low parts count!
A question for anyone in the know about adapting audio mixers and other stuff, related directly to:
But assuming i do this, I will still not have 0-1v clipping of incoming frequencies, and hence the mosule will sometimes output voltages in excess of the 0-1v used in the lzx ecosystem, right? So if i wanted a proper lzx 0-1v, i would have to adapt the whole circuit? Or is that overkill for just a simple mixer? This is most definately out of my competence in the near future …
But just swapping a few components could certainly be done.
there is also a schematic of the summing mixer in the LZX archive.
4ch video mixer. (for LZX format signals)
if you are into DIY build one. I’ve some pcb’s left if you want the easy route.
Yup, im embarking on that route, the summing mixer, VCA and Crossfader (and some other audio rate DIY stuff, to be used for the audio into video synth routing, attenuation, switching, Some LFOs, perhaps a Quadrature LFO, perhaps the OScilloscope graphics artist) are on my to do list. Have plans for getting into designing the PCBs for those together with a friend, af first steps into the design your own PCBs, but If you have spare PCBs or perhaps just files that can be used for ordering PCBs for some of those, im interested, will send a personal message. Thanks!
If anyone is in the same boat but doesn’t want to design the PCBs: The cadet crossfader is basically the same circuit. Also, the BSO QVAM is very similar to the summing mixer but with some improvements. As far as I know, Nick (BSO) is open to selling unpopulated PCBs for it.
For the most part, it doesn’t matter if a mixer with swapped op amps is clipping signals at 1V or not, since whatever LZX gear you plug it into most likely will clip it to 1V anyway, since the inputs are usually (or always?) designed so that higher voltages plugged in won’t damage them.
Just FYI my company Mystic Circuits is working on some new LZX compatible video modules and my goal is 100% to have them have through hole/ DIY/ open source options to expand the DIY video landscape.
Love y’all’s work! 0hp series is a brilliant idea!
you are awesome! This attitude for open source is so great for the community.
I am so glad that it is now possible for non-rich persons to build and play live with these modular video synths.
oooh nice I’m really feeling the DIY gods pulling me their way
I want to start with something very simple
all I’ve done soldering/electronics wise is fixed banana jacks and made passive switches
I’d love to know more
Has anyone explored lars’ gamma circuit further as a DIY?
not yet. but I was planning a extended VCO. (with more waveshapes)
This might be a good addition
Lars mentioned at some point some noise module for the Cadets, I guess is just matter of time since the Oompa Loompas @ LZX are very busy.
Don’t hold your collective breaths waiting for my project backlog to clear, but i’m also kicking around the idea of doing some cadet/castle-format modules.
My current short list is:
- A tri->sine shaper
- A “Scan generator”: an adjustable linear-> trapezoid function.
With faders, crossfade across multiple video sources.
Three of these will make a voltage-> hue function.
I think they might also be useful as a sort of soft “window” key
- Gamma shaper
- Wave folder
- Something along the lines of RGB <-> YUV
- Resettable Monostable/bistable. Think trigger delay/ key latcher
I also want to look at an audio in + audio filter + envelope extraction module, but i’m not quite sure if it will fit in the form factor with what i want to achieve.
Gamma shaping (as Lars is hinting) is probably achievable with a processor and two faders (and some creative patching). I’ll probably spend some time playing with that before deciding whether to invest the time.
I’ll probably spend some time working through this list and abandon some of them on the way (Especially if someone else beats me to the punch)
This is the purpose of cadets! To give us basic building blocks of other stuff so we can create and evolve our own modules… and perhaps new Video specific Eurorack Manufacturers?
A good video rate quadrature VCO would be nice…