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Note: Drawing names within the drawings specify .BMP because they are BMP files in my system. For conservation of space, they are saved in the archive as GIF. This device uses an XOR feedback shift register of 4 bits to generate 15 different repeating patterns of bits. The bits are translated to analog levels and are mixed and amplified. Twisting the mixer knobs changes the characteristic sound quite profoundly. Exactly what any knob does is interdependant on the rest of the knob and switch settings. The switches control the pattern being generated and the pots control the level and phase of the ever toggling parallel outputs of the shift register. The pattern selected will also perform an inherent divide down of the VCO clock to it. For example, you can select a pattern that has 3 states in it's sequence. This selection would provide a complex waveform with a division factor of 3. The VCO would be running at 3 times the waveform frequency, giving a nice perfect fifth relationship. The input was designed to be driven by the VCNGVCO system, which is a FatMan compatible VCO with a CMOS clock driver. The output circuit was designed to drive a FatMan by connecting the output to IC17 pin 3. It would be better, however, to build and connect through a FATMIXER. The schematics for these are in or near the same place you found this. The "reset" switch is there in case you generate an all ones pattern in the shift register. This will cause the generator to be silent. Once reset, the XOR feedback system will function continuously until the switches are again changed. I find the need to use this switch rare. Power supply design, bypassing and connecting unused CMOS inputs to a rail is your responsibility and is left out of all of my schematics to keep them cleaner and more easy to read. If you build this, please send comments, good and bad to me: music.maker@gte.net. |