Noisey chips

Preamble

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

Preamble

Following on from Atari Punx…, which was my first foray into the world of electronic sound generation, 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…

Preamble

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.

Continue reading Banging noises…