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
1 Reply
Tag 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.
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.
UPDATE: Values of R2 and R3 can be changed to 4.7K to obtain more expressive sweep.
This circuit is published under Creative Commons «Attribution-NonCommercial-NoDerivs» 3.0 license.
Any use beyond this license must be discussed with author.
Adjustable Tom
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.
The idea was to design power supply that is small, light, not so noisy, cheap and easy to build. This supply can be used as test supply in a lab or as a PSU for small, portable cabinet.
Schematics. The circuit is based on half-wave rectifier. AC splits in two lines and virtual ground with D1 and D2 diodes. The positive voltage is sustained by electrolytic capacitor C2 and ceramic capacitor C4, which is more fast. Then it goes to positive voltage regulator U2, followed by filtering capacitor C7, and protection diodes D3, D5. Minimal load and indication is provided with R2 resistor and D8 LED. The value of the resistor is to be selected manually to obtain comfortable brightness. I used 15K. The negative voltage bus is similar with different polarity and different regulator. The +5v bus is even simplier and utilize low-current regulator, 78L05.
.
The Board. The whole circuit including heatsinks, seven 16-pin IDC-connectors and mounting holes, can fit on one 37×24 holes stripboard. Because of simplicity of the circuit, there is very few cuts and jumpers needed.
This is how it looks inside 3U rack chasis.
This circuit is published under Creative Commons «Attribution-NonCommercial-ShareAlike» 3.0 license.
Any use beyond this license must be discussed with author.
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.
Voltage of the regulated power supply can be precisely set to obtain ideal symmetry for the oscillators, stable tune and low noise floor. This power supply consists of bridge rectifier, filter and three identical parts of voltage refulation, protection and indication circuitry. The positive line works as following: Bridge (D1, D3) rectifies AC, then it being filtered with two 3300uF capacitors (C1, C3) and 100n ceramic disk capacitor (C5) which are connected in parallel. Then goes LM317 regulator working as Adjustable regulator. (IC2, R2, R5, D8, C8) The load resistor (R8) and LED provide both indication and minimal load required for adjustment. The resistor value should be between 2K—10K, so it’s better to find LED which is not very bright.
The negative line works identical to positive with exception of LM337 used as regulator.
This circuit is very similar to Ken Stone’s solution. I believe, he was inspired by LM317 datasheet too.
Version 1.2
Schematic
Component view
PCB Layout (mirrored)
BOM
| Part | Quantity | Value | Package |
| C1,C2,C3,C4 | 4 | 3300u 35v | E7,5-18 |
| C5,C6 | 2 | 100n 35v Ceramic | C050-024X044 |
| C7,C8,C9 | 3 | 10u 16v | E2,5-5 |
| D1-D13 | 13 | 1n4004 / 1n4002 | DO41-10 |
| IC1,IC2 | 2 | LM317 | 317TS |
| IC3 | 1 | LM337 | 337TS |
| J1,J2,J3,J4 | 4 | Terminal block 2pos 5MM
(or 2pcs 4pos) |
TERMINAL_BLOCK_2P_5 |
| JP1 | 1 | Header 2×8 pins | 2X08 |
| LED1 | 1 | 3mm Red LED | LED3MM |
| LED2 | 1 | 3mm Yellow LED | LED3MM |
| LED3 | 1 | 3mm Blue LED | LED3MM |
| R1,R2,R3 | 3 | 10K Trimmer Bourns W3296 | S64W |
| R4,R5,R6 | 3 | 1K 1/4W 1% | 0207/10 |
| R7 | 1 | 4K7 1/4W 1% | 0207/10 |
| R8,R9 | 2 | 10K 1/4W 1% | 0207/10 |
Assembled unit (old version) looks like this:
This circuit is published under Creative Commons «Attribution-NonCommercial-ShareAlike» 3.0 license.
Any use beyond this license must be discussed with author.
CV/Gate inputs for the RITM-2 synthesizer
Sorry, but english version of this page is very brief due to large amount of text that need to be translated. Feel free to contact me if you’re interested to modify this brilliant soviet synthesizer and have questions about schematics shown below. Thanks for understanding.
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