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…
I think™ you could probably make a workable quadrature shaper with the IX and some analog switches and a comparator. (You can split the triangle from the IX into four separate “zones” and then offset and invert as needed to stitch it back together) This works at audio rates, but the switching might be a problem at video rate.
Alternately, invert-chop the TRI into a SAW (Which can trivially be wavefolded back into a TRI), offset it (by a CV-able amount), and then fold it back. if the wavefolder is precise and fast enough, this would give you a new TRI with controllable phase offset. As with the other approach, this depends on speed and precision to work glitchlessly
I tried that gamma trick, (triangle VCO to Multiplier CV & input) . it gives a very nice waveform.
This definitely goes into the next vco pcb!
how can you chop a saw from a triangle and get the full range? I patched it with a squarewave into the Fader, but that gives me a half saw (1/2 of the triangle)
I also did the pedestal mod , it has interesting effects on the shape and frequency.
Fade with the square between the TRI and an inverted and offset TRI. (flip the tri around on the down slope).
would this be possible with patching, you think?
Vco (with squarewave mod), Fader & Processor / Multplier ?
I think so? mult the tri to fader A and processor, turn the processor amount fully ccw, plug processor output to B, SQW to fader in and adjust the bias on the processor until to get it matching (I think you want the bias to post and fully clockwise). Be aware that this gets you a 0->2V SAW, so either adjust the amplitude with another processor or adjust the input amount on the next module in chain accordingly
Note that if you’re redesigning/modding pcb’s, remember that you can swap the expensive/rare fader parts an analog switch if you’re not actually fading inbetween the extremes. (for example for the tri->saw)
I may get back to you about that when I do the layout. Thanks!