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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 VCF MK's Diode Ladder VCF 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 the footprint. Some options: Bourns PTL series, such as: * https://www.mouser.com/ProductDetail/Bourns/PTL30-15O0-105A2?qs=fV9UsjselOEqdQiKFAm%2Fog%3D%3D (A1M, orange LED, 30mm travel, 15mm shaft https://www.digikey.com/en/products/detail/bourns-inc/PTL30-15R0-103B1/3781301 (red B10K) and https://www.digikey.com/en/products/detail/bourns-inc/PTL30-15O0-105A2/7314942 (orange A1M * The 16 mm pots had long enough terminals, barely, to poke through the board, connecting a trace on one side when convenient. You can even use a ground plane on only one side //calculated x value of exact middle of panel after deducting left/right sub-panels // top horizontal rib h_wall(h=4, l=right_rib_x); } module title(string.

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