x0x-heart
About the x0x-heart
The x0x-heart is the heart of the x0xb0x, surgically extracted from the x0x to be transplanted into your designs. The x0x is a faithful replica of the Roland TB-303, complete with sequencer and DIN/MIDI/USB. The x0x-heart is just the analog section of the TB-303, replicated with SMT components, and made small enough to fit into a Eurorack modular format. It even has a Eurorack power header on it.
The x0x-heart is designed to be small, inexpensive, and a close replica of the TB-303. It is not a perfect replica - some sacrifices were made to keep costs down - but its pretty darn close. It also has no pots or controls, making it great for DIY synth building. All of the useful control points are pinned out on 0.1" spacings for easy prototyping. And, as a special bonus feature, digital control is given for Accent, Slide, Waveform select, Cutoff, and Envelope mod.
User Manual
Differences from the original 303
Of the original transistors that are still available, none are available in SMT, so all new transistors were used. The PMP4201/5201 matched pairs were selected, and use throughout. These have very similar characteristics to the 2SC2291 and 2SC1583 matched pairs used in the 303, but have better matching characteristics.
Mods
