The Power supply schematic was updated. Also PCB for toner transfer was published.
Previous version has graphical errors and should be forgotten.
Regulated Bipolar PSU schematic update
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Category Archives: Schematics
ESI Gigaport HD DC-Coupling Mod
There is number of DAW-sequencer plug-ins that can work with control voltages. For example: Expert Sleepers Silent Way and M.O.T.U. Volta. Also, any specific CV source can be made with SynthEdit, SynthMaker, Pure Data, Max/MSP etc. In order to output CV to a hardware, an audio-interface with DC-coupled analog outputs is required. (Audio-interface should work correctly with direct current) Most of today’s audio-interfaces have protecting HP filters, placed right before analog outputs. These filters let only alternating current to be passed trough (outputs are AC-coupled) and also provide good dynamic range. Few old professional interfaces (MOTU 828 and others) has DC-coupled outputs. Also, Expert Sleepers has the whole range of specialized audio-interfaces and DACs with DC-coupled outputs. These are good interfaces, but a bit expensive.
The ESI Gigaport HD is known as inexpensive, multichannel 24/96-ready USB audio-interface. Out of the box this interface has AC-coupled outputs but circuit can be easily modified to support CV.
There is eight electrolytic capacitors inside the device: C36, C41, C46…C71 (marked red). All we have to do is to short capacitor’s terminals together. The first option is to solder a jumper wires around each cap. The second option is to insert switches that could toggle DC- or AC-coupling for individual outputs.
Finally we got an interface that supports both CV and audio.
Measured specifications
- Channel number: 8
- Amplitude: 6v p-p max. (−3…+3 volts)
- Maximal positive sample value (32767 или 8388607) inverts (Version 3 drivers)!
- Channel DC cross-talk: <0.03% (<146dB)
Use carefully! Unprotected inputs/outputs are sensitive to low-impedance current sources. Inaccurate connection may cause damage to interface or degrade it’s specs.
Regulated Bipolar PSU
To feed modular system, you need bipolar power supply giving voltages from ±9v to ±18v depending from used system. Additional power lines might be needed. Eurorack standard suggests symmetrical ±12v line and additional +5v line which is useful for MCUs and some another digital ICs. It is possible to use computer power supply for modular systems, but PWM supplies have quite unstable voltage in fluctuating environment. Because of that, tune and volume of the synthesizer powered by PWM supply may have undesirable modulations. In some cases it can be used as artistic effect but to get completely predictable sound you need traditional power supply that uses a transformer.
Here is the one supply of this kind — Regulated Bipolar PSU. It gives enough power for almost any system. Continue reading
Low-Cost PSU
To feed modular system, you need bipolar power supply giving voltages from ±9v to ±18v depending from used system. Additional power lines might be needed. Eurorack standard suggests symmetrical ±12v line and additional +5v line which is useful for MCUs and some another digital ICs. It is possible to use computer power supply for modular systems, but PWM supplies have quite unstable voltage in fluctuating environment. Because of that, tune and volume of the synthesizer powered by PWM supply may have undesirable modulations. In some cases it can be used as artistic effect but to get completely predictable sound you need traditional power supply that uses a transformer.
Here is the example of such kind of supplies — Low-Cost PSU intended to work with external ±12v AC power adapter or external transformer.
Adjustable Tom
Quad Adjustable Tom is minimalistic percussion module that consists of 4 identical analog electronic toms. The main feature of this module is that it is very compact unit built around one Quad Opamp. It is supposed that pitch adjustment is rare operation that can be done with on-board trimmer potentiometers while the front panel has only gate inputs and audio outputs which consume only 4hp of space. SUch modules can be joined to kind of compact percussion cluster. THe sound of this module is similar to analogue Boss rhythm-boxes.
adjustable_tom_test1
The sound example contains all four toms played in serie. There are dry at the begin and then some reverb effects are presented.
Continue reading
Wob-Wob Fader
Wob-Wob Fader is simple CV-source controlled by fader. The feature here is that maximal voltage is reached in the middle position. This controller make it possible to easy perform sweeps widely used in modern music. similar technique is used with vinyl disks. This module has one Wob-fader and one fader with selectable mode.
MFOS: Weird Sound Generator
Сегодня я хотел бы наконец рассказать об одном интересном инструменте, который, строго говоря, не является музыкальным инструментом, но относится к вещам, которые интересно было бы иметь любому человеку интересующемся электронной музыкой и культурой аналогового синтеза. Он называется Weird Sound Generator, то-есть генератор чудны́х звуков. Вот как его описывает разработчик, Рэй Уилсон с проекта «Music From Outer Space»:
- WSG делает придурочные, забавные, странные и необычные звуки.
- Стимулирует рост мозговых клеток у людей и животных
- Воздействие WSG на плод способствует развитию гениальности и одарённости.
- Способен оторвать детей от телевизора (вот доказательство:
) - Воздействие WSG на пристарелых граждан способствует подавлению метеоризма.
- Интересно включать во время ланча, закуски и вообще когда угодно (0 калорий)
- Весело использовать во время оперативных совещаний (и скучных совещаний)
- Крайне экономно потребляет ток, так что вы сможете производить чудные звуки очень, очень долго.