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Oakley midiDAC User Manual
Summary of midiDAC
Page 1
Oakley sound systems mididac issue 3 single channel midi-cv convertor user manual and builders guide v3.5.1 tony allgood b.Eng pgce oakley sound systems carlisle united kingdom.
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This is the issue 3 mididac in a natural finish schaeffer panel. Note the new rounded corners. The toggle switches are apem flat blade toggle switches available from farnell. The round led holders come from maplin, whilst the knobs are the rapid's 'matt black control knobs' for 1/4” fitting. 2.
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Introduction for general information on how to build our modules, including circuit board population, mounting front panel components and making up board interconnects please see our generic construction guide at the project webpage or http://www.Oakleysound.Com/construct.Pdf. The issue 3 mididac is...
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Other features there is a note stack within the firmware to allow the mididac to remember notes pressed. Thus if two or more notes are pressed at the same time, the oldest notes will be remembered so that if the more recent notes are removed the pitch will return to the still pressed older notes. Th...
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Board is used as the digital ground and not the chassis ground as on other oakley modules. Connection to the dizzy distribution system will not damage the mididac module, but it may introduce unwanted noise on the power lines. Therefore please connect the mididac directly to the power supply output ...
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The pcb has four mounting holes, one in each corner. However, using the mididac with the recommended pots and brackets, will give you sufficient support without the need for additional mounting hardware. The pots are spectrol 248 series or bi tt equivalents, supplied by farnell, cpc and rapid electr...
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The max551 is a current output multiplying dac. This means two other things are needed to get it to convert digital data to an analogue voltage. Firstly, you need a very accurate reference voltage. This will set the maximum output voltage that the dac circuit will supply. For the mididac the referen...
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Each output section is called a ‘sample and hold’, although to be strict the demultiplexer also forms part of the sample and hold. The capacitor in each s/h holds or stores the voltage that is briefly connected to it. The op-amp that is connected to it, allows this voltage to be ‘sniffed’ without ef...
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Two forms of setting the initial pitch cv are provided. One is the tune pot mounted on the front of the panel. The other is init, which is a multiturn trimmer that will allow precise setting of the initial pitch cv, and thus aid centralising the tune pot’s range. In this version of the mididac, the ...
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The pic also generates two digital type signals direct from its own ports. These are gate and slide. The former goes low when any note on is received on the selected midi channel and will go high when a note off, or key velocity zero, is received. It will briefly blip high in the case of ‘legato mod...
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Gate trigger modes the mididac allows the selection of two gate trigger modes via the ‘legato mode’ switch. This is marked on the new pcb as ‘re-trig’. You can connect a simple spst switch to this or a simple jumper. The setting of this switch/jumper determines how the gate signal responds to overla...
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* in accordance with mma specifications, all notes are cleared when these controller messages are received. Note priority the mididac firmware uses last note priority. That is, it will assign the pitch cv to the last note to be held. However, all 'overlapped' notes are still retained in memory and a...
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Components for general information regarding where to get parts and suggested part numbers please see our useful parts guide at the project webpage or http://www.Oakleysound.Com/parts.Pdf. Some special considerations for this project many of the resistors are 1/4w 5% or better types. Although there ...
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One of the ics is a three pin to92 style package. This is the 78l05 which is a 5v 100ma regulator chip. The multiturn trimmers are the ones that have the adjustment on the top of the box. Spectrol and bourns make these. Some types are 22 turns, while others are 25 turns. Either will do. They should ...
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Parts list for general information regarding where to get parts and suggested part numbers please see our useful parts guide at the project webpage or http://www.Oakleysound.Com/parts.Pdf. The components are grouped into values, the order of the component names is of no particular consequence. A qui...
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Pots 50k linear spectrol 248 tune, bend 100k log spectrol 248 slide capacitors 100nf axial multilayer ceramic c23, c11, c36, c32, c3, c30, c15, c4, c6, c5, c12, c21, c20 10nf 100v polyester film c1, c31, c27, c28, c34, c29, c33 18pf low-k ceramic plate c25, c26, c19 1uf, 63v electrolytic c10 1u5, 63...
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Connectors 4-way molex 0.156” header 1off (psu) 4-way 0.1” header and socket 2 off (cn1, cn2) 3-way 0.1” header and socket 2 off (midi thru and dizzy bus) 2-way 0.1” header and socket 1 off (midi in) miscellaneous 4mhz crystal (parallel resonant) x1 ferrite l1, l2, l3, l4 led clips two off, colours ...
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Connections how you connect your mididac very much depends on where you are going to use the mididac. You may already have an idea of how you are going to connect your mididac to your chosen system. For those building the standard oakley mididac modular panel i will give the wiring instructions in d...
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Separately. It is preferential to use a separate 4-way power lead to the mididac that comes straight from the power supply and not via any other module. The ideal modular would have three grounds, a chassis or safety ground, a clean power supply ground (agnd) and a dirty power supply ground (dgnd). ...
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The rear view of a recently made mididac-3. This one has been built onto a natural finish schaeffer front panel. The sockets are switchcraft 112apc with a small amount of heatshrink acting as a strain relief for the connected wire. No wired ground connection is made to the output sockets. The front ...
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Calibration there are two trimmers on the mididac pcb. Both of them are designed to allow you to make the mididac respond correctly to the rest of the modular system. If you already have a perfectly tuned and calibrated system, it is best to trim the mididac to suit your system rather than the other...
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Final comments if you have any problems with the module, an excellent source of support is the oakley sound forum at muffwiggler.Com. Paul darlow and i are on this group, as well as many other users and builders of oakley modules. If you can't get your project to work, then oakley sound systems are ...