Synthcard VCF

    Okay, I'm designing my SynthCard PCB, and I need a landing page for people who want to build theirs.

    This is a low-pass VCF based generally on an MS-20 filter. The general idea is that it's got two poles for a nice smooth 12dB response. It uses a dual OTA (LM13700) as the resistive elements, and the built-in buffers. Like the MS-20, the feedback circuit, which gives this filter resonance, uses clipping LEDs to get the characteristic growl of this kind of filter. It's designed to work with 12 volts, but will work okay lower, and just fine up to 30 volts, but thirty volts is higher than the SynthCard standard allows so be careful :D

    Make sure you're putting the TL074 and LM13700 chips in correctly -- they're not facing the same way.

    You can use Thonkiconn-style jacks if you want for Eurorack-style patch cables. There's a little pad right next to each Thonkiconn footprint if you'd rather use pins. You can use SynthCard CornerBricks (print them yourself or get them from me) along with DIP-8 spring-type sockets as a way to pass power along all your SynthCards. Remember, the pins for power go in the "back" of the SynthCard if you're gonna use CornerBricks.

    Okay, shoot me an email or find me wherever to ask questions!

    Huge thanks to Benjie Jiao who created the first SynthCard that I'm aware of. He made a business card that could be built into an oscillator based on the Atari Punk Console. We've worked on a standard, which this design probably complies with LOL