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Updated: Jul 18, 2022

I wanted to create very random voltage patterns, using the CV sources from my 0 Coast and Leploop synths (both of which produce a lot of CV outputs)

I quickly get bored of even a complex LFO/clock source, I want it to be really unpredictable though have a relationship of sorts to a pattern.

I decided to make a device using Logic Gates to combine the voltages I have available. Read an intro to logic gates here, amazing invention, essentially computing is not possible without them:

I wanted to have all the universal gates in my design, and have them toggled to an inverter, making inversion possible without an extra patch cable and socket:

(N)AND, (N)OR, X(N)OR where (N) is a NOT gate, inverting the output. To increase randomness even more, I ran each output of these gates through a CMOS 4066 electronic switch, so that the final output of the gate can be switched on and off rapidly (even up to audio frequencies). Each of these gate modules has two inputs and one output.

To make the modules more useful (and also to use more available (on chip) gates, switches, and panel space) I added an 4066 switch as a separate module, two NOT gates, a passive multi connection, and two attenuverters. (attenuates and inverts a voltage) I had some different plans for these sockets during the build, though this was the final selection!

At first I became fascinated by using NAND gates to create all of my desired gates, which is possible by cascading and connecting all four 2 input NAND gates on a chip. However, I used a protoboard which was much too small in my original design. The gates operated, though the function of the device was unstable as a whole. For some reason it did not work if the jacks were grounded (amongst other issues!)

compact and too small

Using a NOS modem case from 1993, I had fun measuring out and drilling the holes:

Happy Jacks

I find working in this way so relaxing

I took a break from the build, and some months later made the protoboard section again, much bigger this time. I also decided to use dedicated AND, OR, XOR chips (instead of making them all from NANDs). This was much simpler and less confusing to connect up!

way bigger way easier!

As you can see, there is plenty of wiring (all hook up wire is recycled in this build) I'd acquired a nice (salvaged) red power switch in the meantime, so at the last minute I installed this as well. The lamp in the switch is dead, I tried to open it up to replace it, but nothing doing. So I added a 3mm power status LED instead, which I had in my salvage stock, with bezel.

back side with logo, power inlet, switch and server handle
All installed, awaiting decals

Next is to print the gate symbols on some vinyl stickers, and add these to the front panel. Similar to these:

I will also print vinyl stickers for the side panels, which are unaltered at the moment. These will have the name CMOS ACID LOGIC 5000 SERIES, in red and white. Inspired by the fonts and typesetting used in 2001 a Space Odyssey. Like this:

Thanks to my brother Tim for helping me with these decals. See his website:


I have added some artwork, semi permanently to the CAL 5000. Most of my projects are like this, they take years to reach the final pinnacle of design. This is not perfectionism, just finding the right style : ) Here I have used the negative section of letter stickers. For this design the negative space of the letter works better than the positive space of the letter. Also you totally get your money's worth from the stickers this way! I added some lines from recycled plastic (actually more sticker waste from stick on plastic feet) to indicate connections between jacks. The inverting N symbol is marked with an asterisk (actually a dot, but used as an asterisk) so when you look for the corresponding asterisk the iNverters position can be seen: *AND *N becomes NAND, the N goes to the * position. I'm really happy with how it looks at the moment. Managed to get an 'acid' smiley face in there as well which is awesome.

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