DIY ALERT: Sandin IP PCBs: show us your builds and videos!

[tke]

vidiot + differentiator / function generator - can someone point me towards some simple patch ideas - just to test that both DIY modules are working fine.

[davev]

@jnoble @creatorlars I got to see the SAIC Sandin last week and am inspired. The links no longer work for the source file PDFs of your modules - Could you please send me a link to the source for these? I’d love to take a look, learn from what you did, and try my hand at translating another of the old modules to fill out the system.

Thanks!

[joem]

I’m not sure if the LZX versions that were shared earlier in this thread are currently shared anywhere, but there’s a version of the LZX version of the Differentiator that @pbalj made here: GitHub - Teletect/IP-Differentiator: Eurorack 4hp Sandin IP Differentiator

Also, @reverselandfill made a triple function generator which if I’m not mistaken is very similar to the the LZX version of the single Function generator circuit, but done three times: Triple Function Generator – Reverselandfill

[creatorlars]

The links from Joe above are good! Let me know if you want to talk thru implementation of any of the other Sandin IP modules, I can advise on parts or strategies to employ for any of them. Generally it’s all pretty doable to do the functional clones! But you’ll need to use different IO buffering strategies and different ICs in many cases. The Adder/Multiplier for example, could be built from function blocks documented in the Cadet 7 and Cadet 6 projects.

[davev]

Thanks @creatorlars! and @joem! I’ll take a look.

[davev]

@creatorlars - On the function generator Instead of using Dan’s original “Standard Driver” (Complimentary Current Amplifier) it looks like you are using 2 inverting stages of the LM6172 op amps. Instead of 75ohm output impedance, you use 499ohm. Can you help me understand these changes? Is this a change to play well with LZX standards?

[Robbertunist]

Have you checked out these 2 pages @davev?

The LZX Patchable Video Standard

[WORK IN PROGRESS, FEEDBACK IN THREAD WELCOMED] LZX Industries Patchable Video Standard V1.0 The Patchable Video Standard proposes an electrical and interface specification for wide bandwidth analog computing instruments intended for creative and expressive applications. It is optimized for, but not limited to: (1) generating and processing analog RGB video graphics in SD resolutions, (2) affordable devices which are accessible to working artists and not just big studios, and (3) maximum patcha…

Under the first one, 499r output impedence is discussed.

I haven’t looked at this page but the title sounds suitable:

1V DC vs 75R Video

How does 1V DC signal differ from 75R Video signal? Vidiot has these distinctions in Luma and Colorizer sections. I know LVX is driving the 1V standard, but what does that mean? Is it simple enough to explain here or where is a good source to read up?

[creatorlars]

@davev

On the function generator Instead of using Dan’s original “Standard Driver” (Complimentary Current Amplifier) it looks like you are using 2 inverting stages of the LM6172 op amps. Instead of 75ohm output impedance, you use 499ohm. Can you help me understand these changes? Is this a change to play well with LZX standards?

Correct. Sandin IP originally used +/-0.5V signals driven at 2X gain (+/-1V) with low impedance (75R) inputs. LZX (and compatible makers) use 0-1V DC signals with high impedance (100K) inputs, which make them compatible with EuroRack modules and other synthesizers.

So in doing these adaptations, I treated it like you have a frontend/backend circuit at the IO, with an application circuit in between. I replaced the frontend/backend circuits from the original Sandin IP circuits with typical LZX 1V buffer/driver circuits (you can find reference designs in the Cadet schematics.) The application circuit in between, I redesigned with modern replacements for any obsolete/unobtainable ICs, but tried to keep anything else as similar to the original designs as possible.

Dan got to see the outputs from the adaptation modules and give them his approval before we released the designs – he said the results were much cleaner than the original IP in terms of noise floor, and that the functions worked as he had originally intended.

[davev]

Thanks for the info. very helpful.