Summary of Contents for Slightly Nasty 2111
- Page 1 M O D E L 2 1 1 1 R A N D O M VO LTAG E S O U R C E R a n d o m V o l t a g e S o u r c e Construction &...
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Page 2: Ext. Clock
R a n d o m V o l t a g e S o u r c e PHYSICAL FORM FACTOR: Loudest Warning / 4U WIDTH: 3NMW / 75.5mm HEIGHT: 175mm DEPTH: ~25mm from panel front inc. components PCB: 70 x 75mm, Double Sided CONNECTORS: 4mm Banana... -
Page 3: Table Of Contents
Filter Stages Voltage Controlled Clock Shift Register Slew Circuit CHOOSING COMPONENTS Bill Of Materials (BOM) Choosing Components CONSTRUCTION Construction Overview Physical Assembly CALIBRATION Calibrating the 2111 CONTROLS Controls REFERENCE PCB Guide This document is best viewed in dual-page mode. Circuit Overview... -
Page 4: Introduction
The Clock can run into audio rates as well, to create interesting voltage-controllable noise effects. The two logic outputs on the 2111 are the clock output, which is self explanatory, and the Random Logic output - which follows the first bit of the shift register and is useful as a random two-state modulation source, a random gate/trigger signal for envelopes etc., or an Atari 2600-style digital noise signal. -
Page 5: Noise Core
For full schematics, please download the separate schematics PDF. Excerpts shown in this manual may be outdated and are provided for reference only. The Model 2111 can be functionally broken down into five separate sub-circuits: 1. Noise Core - This generates the raw white noise signal by amplifying the natural avalanche noise of a zener diode. - Page 6 Circuit Overview...
- Page 7 R a n d o m V o l t a g e S o u r c e The noise core of the Model 2111 uses the natural avalanche noise of a zener diiode to create the noise signal used by the rest of the module. The most important components here are the zener diode D201 and the amplifying transistor Q201 (configured as an inverting amplifier).
- Page 8 2231 Asymmetric Slew Limiter is a simple way of removing this interdependency. The voltage controlled clock in the 2111 is comprised of three main circuits - the CV summing amplifier, the exponential current source, and the sawtooth oscillator, with a couple of auxilary circuits that clean up and process clock input/output signals.
- Page 9 Circuit Overview...
- Page 10 U401D, which is simply a comparator with a small degree of hysteresis to prevent oscillation. The heart of the 2111 is arguably the shift register circuit, which provides the functionality of the clocked random voltage outputs. This circuit is based around a 74HC164 8-bit shift register IC (U302A), which takes as its serial input a heavily amplified and diode-clipped version of the "light"...
- Page 11 Circuit Overview...
- Page 12 R a n d o m V o l t a g e S o u r c e given value in DAC1 would always result in the same output on DAC2). The outputs of the DACs are amplified and offset by the inverting amplifiers around U301B and U301D to buffer and convert the 0-5V output of the DACs to the +/-5V that we want at the output jack.
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Page 13: Slew Circuit
A s y m m e t r i c S l e w L i m i t e r R a n d o m V o l t a g e S o u r c e The slew circuit provides an additional output that is a linearly-slewed version of the A-B output, using a basic integrator-comparator circuit. -
Page 14: Bill Of Materials (Bom)
Bill of Materials... -
Page 15: Choosing Components
R a n d o m V o l t a g e S o u r c e Like all Slightly Nasty modules, the 2111 is designed to use common "jellybean" components wherever possible, so getting hold of parts is relatively straightforward. -
Page 16: Construction
I personally like to clean up any remaining protrusions with a few passes of a needle file as well. The SPDT switch in the 2111 is probably the component that requires the most attention during construction. Soldering the switch into place should always be... - Page 17 R a n d o m V o l t a g e S o u r c e needs a bit of additional care when assembling to ensure correct aligment. The best course of action is to solder one side of all the interconnects (either the pins or socket) into place, being careful to get them straight and flush with the board.
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Page 18: Before You Begin
PCB. The 2111 has only one trimpot to adjust, so calibration is very simple. The trimmer RV403 sets the lowest clock speed for the voltage controlled clock, and can be set by simply turning the front panel clock rate knob all the way down, then adjusting the trimmer to the desired rate. -
Page 19: Controls
Outputs a slew-limited version of Sets the slew rate of the slewed random voltage A-B random output. Higher is slower S L I G H T LY N A S T Y SLIGHTLY NASTY JACK COLOURS Bipolar signal output BLUE Bipolar signal input YELLOW... -
Page 20: Pcb Guide
R a n d o m V o l t a g e S o u r c e LOWER BOARD - TOP LOWER BOARD - BOTTOM PCB Guide... - Page 21 R a n d o m V o l t a g e S o u r c e UPPER BOARD - TOP UPPER BOARD - BOTTOM PCB Guide...
- Page 22 w w w . s l i g h t l y n a s t y . c o m...
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