Noisey chips


Following on from Banging noises…, I attempted to recreate the Noise Chip (U4) depicted in the LDB-1 schematic, from the article Anatomy of a drum machine. The noise chip creates both a white noise signal as well as four tuned square waves at different (unknown) frequencies. I have attempted to contact the author for more details but have not had a reply as yet.

It is using either PIC (which is likely seeing as the author states a preference for the PIC microcontrollers), or an ATtiny.  I will attempt to use a ATtiny/ATmega microcontroller (specifically ATmega48P/88P/168P/328P but the code should compile for most Arduinos).

Note that parts of this are a work in progress.

Note: The phase-correct 50% trick is possible with Timer0 on an ATtiny85, but it is not clear if it is possible with Timer1 (although Timer0 does have two channels). Atmel AVR ATtiny comparison chart

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Sequence Dancing


Following on from Atari Punx…, which was my first foray into the world of electronic sound generation, it seemed that a sequencer is a very useful piece of additional kit. One can be easily made using a CD4017 decade counter (or CD4022 octal counter)… However, other ICs can be used, to provide additional functionality. For example, a CD4510/CD4516 BCD/Binary counter and a decoder or 16 channel multiplexer, such as a CD4028 or CD4067, can add up/down sequencing, pre-loading and other features.

Let’s take a look at all of these ICs as well as some others.

VCO, VCF and VCA circuits are also touched upon, be are covered more fully in Banging noises…

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Banging noises…


As a follow on from Atari Punx… a home grown, simple, drum machine is required, to accompany the APC. It was first thought that a 555 based drum machine would suffice, but a µController is required for sequencing really, or a counter. However, the topic of sequencers is covered in the separate article Sequence Dancing.

This article deals with sound generating circuits, principally oscillators and filters..

White noise generators are also looked at.

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