https://electro-music.com/forum/ https://electro-music.com/forum/viewtopic.php?p=458100#458100 Both very good questions! I'm going to control it digitally with a microcontroller through a 16 bit DAC, so it doesn't really matter whether it's linear or expo as I can just create a lookup table.

As to why the LM3900.... good call! I just had so ... TryHard Wed, 21 Jan 2026 05:58:04 -0700 https://electro-music.com/forum/viewtopic.php?p=457638#457638 Hi!
Francesco (urbanspaceman) here — I wanted to share a project I’m working on with my company that might interest a lot of people here on EM.

Here’s the link:
https://www.indiegogo.com/projects/cosmolab-diy-synthesizers-fx-midi-eurorack ... urbanspaceman Fri, 26 Sep 2025 04:43:09 -0700 https://electro-music.com/forum/viewtopic.php?p=457632#457632 This is cool. Thanks for sharing. It looks similar to the Korg 35 filter (early Korg MS-20). Cynosure Wed, 24 Sep 2025 12:36:59 -0700 https://electro-music.com/forum/viewtopic.php?p=457573#457573 Hello! Greetings from Argentina. While searching for variable filter circuits, I ended up here. I designed a PCB based on the schematics I found in this forum and added an output for the high-pass filter. elrengofa Sun, 14 Sep 2025 17:48:13 -0700 https://electro-music.com/forum/viewtopic.php?p=456652#456652 Just done some experimenting and found that multiplying by envelope_level then dividing by 511 before adding 511 works fine. Mickeyluv Tue, 25 Mar 2025 10:07:43 -0700 https://electro-music.com/forum/viewtopic.php?p=456327#456327 thanks for sharing this ,this is exactly what i needed ,as i was looking at some passive filters from 9th issue of electronotes and those all need that expensive coil of 500 mhy ,i built the SIAM (Siemens inspired EQ) that also has 8 gyrators and it m ... vladosh Fri, 10 Jan 2025 07:23:12 -0700 https://electro-music.com/forum/viewtopic.php?p=455757#455757 updated and as-built zaphod betamax Wed, 14 Aug 2024 10:47:39 -0700 https://electro-music.com/forum/viewtopic.php?p=455555#455555 Thanks for the clarification Jan! glnds Tue, 11 Jun 2024 14:20:43 -0700 https://electro-music.com/forum/viewtopic.php?p=455492#455492 Wow, I did not expect these chips to be so inexpensive.

Page 21 of the datasheet shows that the output from the VCO chip is from it's internal mixer and does not require an external buffer. If your design uses phone plugs and jacks, I would sug ... alkopop79 Sun, 26 May 2024 09:03:27 -0700 https://electro-music.com/forum/viewtopic.php?p=454659#454659 Well .. i don't know about finite elements (I assume you meant with FEM) in relation to reverb and I don't know what methods could be used to make directional reverb.

What I do know is that when you set up delay lines of acertain lengh you canfreel ... blue hell Wed, 15 Nov 2023 10:29:26 -0700 https://electro-music.com/forum/viewtopic.php?p=454391#454391 Unfortunately, I lost all my old STM32 Nucleo boards in a storage fire, so I recently picked up a couple of Electro-Smith Daisy Seed boards (STM32H750-based).

I ported the NucleoSynth code over to run on these new boards.

There is the STM32CubeI ... nettech Fri, 22 Sep 2023 18:29:17 -0700 https://electro-music.com/forum/viewtopic.php?p=453707#453707 A schematic would be very helpful if not necessary in answering your question. Grumble Thu, 27 Apr 2023 22:21:05 -0700 https://electro-music.com/forum/viewtopic.php?p=452778#452778 I always suggest www.musicfromouterspace.com for newbie's because there are some projects for starters and they all come with explanations on how it all works. PCB's for the projects can you buy from www.soundtronics.co.uk or you can find layouts for ... Sven Wed, 26 Oct 2022 10:44:58 -0700 https://electro-music.com/forum/viewtopic.php?p=452555#452555 I'm teaching ECE3400: Analog Electronics, a junior-level elective at Georgia Tech, this semester. Like with my "Analog Circuits for Music Synthesis" and "Guitar Amplification and Effects" classes, I'm recording some lectures for it and putting them on ... abovenyquist Wed, 14 Sep 2022 11:32:02 -0700 https://electro-music.com/forum/viewtopic.php?p=452540#452540 Hi all;

I've recently been trying to build a two-pole VCF with the LM3900 as the voltage control element, just to see how it would do. I'm basing the filter structure and CV system on an Osamu Hoshuyama phaser design, so I can't take credit for how ... Gogledd Sat, 10 Sep 2022 08:27:41 -0700 https://electro-music.com/forum/viewtopic.php?p=452163#452163 And thank you again :lol:

You are very welcome, Grumble! :D RykAntoniuk Sat, 16 Jul 2022 16:47:53 -0700 https://electro-music.com/forum/viewtopic.php?p=452158#452158 I love the sound of the unit! Great timbres from the VCF that you added to it! Together, a very liquid’ish sound! Especially with the amplitude modulation from the external oscillator! RykAntoniuk Fri, 15 Jul 2022 13:30:19 -0700 https://electro-music.com/forum/viewtopic.php?p=452157#452157 Whoa! Well done! RykAntoniuk Fri, 15 Jul 2022 13:22:01 -0700 https://electro-music.com/forum/viewtopic.php?p=452155#452155 :D Great cover! RykAntoniuk Fri, 15 Jul 2022 13:13:03 -0700 https://electro-music.com/forum/viewtopic.php?p=452097#452097 Everything is described in the datasheet on page 4. You can use Figure1 on page 5. The formula for the output frequency is given. I would try a 10K potentiometer for R1 and start with 1µF for C1. The datasheet also has a diagrams for the output frequ ... Sven Mon, 27 Jun 2022 23:55:32 -0700