Generating interesting patterns

[ianbax]

Hi all,

At the heart of my lunetta system is a 'sequential resistance source' - i.e. a 4051 multiplexer linked to 8 potentiometers which can be selected with the binary inputs A B and C brought from the 4051 IC to the front panel. The selected resistance is patched into an oscillator's pitch pot and I can produce pitch patterns.

Hooking it up to a binary counter gives repeating sequences 1-8 and I'm investigating up/down counters (e.g CD4516) for forward and backward operation - although I can't work out how to make them 'bounce' forward then back (1-8 then 8-1).

I've also successfully extracted random 0s and 1s from a electric druid LSFR noise chip, shift register and flip flops. But as anyone who has done this sort of thing knows truly random patterns get a bit boring after a while (I've had better results patching the random gate to the reset of the counter so you get random lengths of a familiar pattern).

Anyway, I'm wondering if there's any other interesting patterns - that generate 3 bit numbers that can be generated from logic chips. I saw the thread on Sierpinski triangles although I wasn't quite sure how I would patch that to a 3 bit selection.

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My synth/sequencer the "Melody Oracle" (see thread here https://electro-music.com/forum/topic-68735.html ) uses the same concept: CD4051 sequential resistance source with CD4040 to sequence it. You can get a lot of cool stuff by patching different pins from the CD4040 into the ABC inputs on the 4051.

One trick that I added in was the ability to invert the pattern (using CD4070 XOR gates). A pattern from the CD4040 that is sequencing in order 0-7 will switch direction (7-0) when the input patterns to ABC are all inverted. That is just one of the cool things that happens with inverting the input patterns. There are a lot of other cool possible results.