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Update 'Future Modules'

gdorn 2022-09-02 04:10:09 +00:00
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Future-Modules.md

@ -4,28 +4,48 @@ What we build next?
Pretty confident we do these in this order next. Pretty confident we do these in this order next.
## Sequencer ## Sequencer
#### MK's 5-step sequencer, expanded to baby 8 Something to generate CV, in particular for controlling VCO notes. The classic is called a "Baby 8", so called because it's a simple circuit that generates a sequence of 8 voltages controllable by individual knobs.
#### MK's 5-step sequencer, expanded to 8 (or 10?)
* Breadboard MK's 5-note sequencer. * Breadboard MK's 5-note sequencer.
* Compare to online 8-note sequencers (baby 8) * Compare to online 8-note sequencers (baby 8)
* Either build online 8-note schematic, or extend MK's 5-note to 8-note. * Either build online 8-note schematic, or extend MK's 5-note to 8-note.
* padding MK's out to 8 notes means roughly $16-20 in parts, depending on PCB choice * expanding out to 8 notes means ~$16-20 in parts, depending on PCB choices
* could also go to 10 steps, but no more (uses a decade counter) * could also go to 10 steps, but limited by decade counter
#### Bergman's 10-step sequencer (up to 10) #### Bergman's 10-step sequencer (up to 10)
* https://www.eddybergman.com/2022/04/8-step-sequencer-v2.html * https://www.eddybergman.com/2022/04/8-step-sequencer-v2.html
* can do up to 10 steps with the hardware to support it * very similar core to MK's, but using fewer diodes (substituting LEDs in many places)
* 10-step mode is ~$16 in parts, depending on which are actually needed * might be more stable than MK's, but it's unclear what that means and whether it is true.
* big board, requiring one 8-pin, one 14-pin and one 16-pin IC * weird usage of a hex inverter, maybe for stability?
* maybe more stable than MK's? test this * 10-step mode is ~$16-20 in parts, depending on which are actually needed
* includes weird 8V linear regulator for the hex inverter - maybe save a bunch of effort and pins by using a single tl074, with two as needed and one as schmitt trigger? * big board, requiring one 8-pin, one 14-pin and one 16-pin IC. But 3 panel-mounted UI elements for every step (plus some others), so plenty of room for a big board behind it.
* includes weird 8V linear regulator for the hex inverter; if this can be replaced by an op amp in schmidt inverter mode, maybe both 7808 and hex inverter trigger are unnecessary?
### Alternative: Midi -> CV
We could generate CV some other way for now, such as:
* build a keyboard using one of the two keybeds in storage; decipher key matrix, work out either MC or dumb resistor array to output correct volts for each key.
* build a MIDI->CV module
** [Hagiwo's cheap arduino version](https://www.youtube.com/watch?v=bHiZhLAntNI) and https://github.com/elkayem/midi2cv which it is based on
** https://www.instructables.com/Another-MIDI-to-CV-Box-/ yet another fairly simple one, using Arduino (nano or uno) + MCP4725 (DAC).
** https://hkadesign.org.uk/monotronkb.html for yet another version
### Alternative: CV from something else
* use a [raspberry pi running a DAW](https://old.reddit.com/r/synthdiy/comments/vbaj43/my_opensource_synthsamplersequencerdawinabox_the/) with a DAC and just use python to send CV; could also do midi-over-usb
* buy a Korg SQ-1, which is what MK uses (and runs about $100 on ebay); Korg lists Trade-Up Music as a vendor?
## VCF ## VCF
#### MK's Diode Ladder VCF #### MK's Diode Ladder VCF
* ~$8 in parts, two tl074 op amps and otherwise a bunch of diodes and support * ~$8 in parts, two tl074 op amps and otherwise a bunch of diodes and support
#### Kassutronic's KS-20
* https://kassu2000.blogspot.com/2019/07/ks-20-filter.html
** uses an LM13700 OTA (operational transconductance amplifier) (~$1.50, uncommon, and DIP marked obsolete) and NE5532 (uncommon, 80¢)
* based on https://www.schmitzbits.de/ms20.html which is an attempted clone of a Korg MS-20.
** that one uses a CA3080 OTA, an expensive and rare chip these days ($3/ea on amazon, maybe fakes)
## VCA ## VCA
#### MK's VCA #### MK's VCA
@ -58,7 +78,7 @@ Something to take CV in, round it to the nearest 1/12th of a volt (or whatever,
* uses an arduino nano (other options probably fine), two 74HC595 shift registers (accidentally a pile in my collection) and the MCP4922 DAC (others may work). * uses an arduino nano (other options probably fine), two 74HC595 shift registers (accidentally a pile in my collection) and the MCP4922 DAC (others may work).
* Probably can build our own based on this and/or Hagiwo's quantizer, if going digital * Probably can build our own based on this and/or Hagiwo's quantizer, if going digital
** https://www.quinie.nl/hagiwo-quantizer-how-does-it-work-a-bit-of-background/ ** https://www.quinie.nl/hagiwo-quantizer-how-does-it-work-a-bit-of-background/
** https://note.com/solder_state/n/nde97a0516f03 ** https://note.com/solder_state/n/nde97a0516f03 and https://www.youtube.com/watch?v=op_DhPr2goc
** arduino nano clone (atmega 328p), 12-bit dac (mcp4726) and small amounts of supporting hardware ** arduino nano clone (atmega 328p), 12-bit dac (mcp4726) and small amounts of supporting hardware
#### Microcontroller and smoothed PWM #### Microcontroller and smoothed PWM
@ -134,6 +154,12 @@ Everybody needs several VCFs with different behaviors.
** CA3080 High-Performance Operational Transconductance Amplifiers - not a jellybean, so $3/ea for sketchy NOS on amazon ** CA3080 High-Performance Operational Transconductance Amplifiers - not a jellybean, so $3/ea for sketchy NOS on amazon
** CA3080 design is ancient; maybe an updated one exists with current ICs? ** CA3080 design is ancient; maybe an updated one exists with current ICs?
#### Scrat
* https://modularaddict.com/scrat-configurable-vcf-neutral-labs
* plug in your own components to hear what they do
* J175 jfet (~50¢) and H11F1M ($5!) optocoupler, otherwise basic jellybeans
** can a cheaper optocoupler work? what's it even for?
## CV Generators ## CV Generators
#### [Ornament & Crime](https://ornament-and-cri.me/) a highly recommenced "polymorphic CV generator" #### [Ornament & Crime](https://ornament-and-cri.me/) a highly recommenced "polymorphic CV generator"