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latigid on

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Posts posted by latigid on

  2. Some questions about building a SeqV4

    in MIDIbox SEQ

    Posted

    Hello, and welcome to the forum.

     

    You have some good ideas for expansion of the SEQ concept but I am not sure exactly how you would go about implementing them.

     

    The parts kit for the Quad IIC is not as extensive for the SEQ, and there is no waiting list for this or the SEQ PCB as far as I know. LCDs can range from cheap and generic to quite expensive; you should check the backlight polarity and interface type (Hitachi HD44780) before ordering.

     

    It should be no trouble to build a simple control surface expansion on veroboard or even a custom PCB. There is a chain connection for additional shift registers on the main board which you can connect DIN and DOUT modules to in order to scan extra buttons or LEDs. Keep in mind that without (semi-complicated) matrix wiring the maximum number of inputs/outputs is 32 per module, you have 34 buttons in your design.

     

    The panel could be easily remodelled for the extra functions. The case is always more work than the panel, it is worth trying to locate this part first.

     

    The software side is where it gets tricky. I wouldn't expect anyone (TK) to program these changes for you as it is a single use-case feature set. It is also unlikely that everything can be run on the same core module due to memory considerations; additional routines may affect the timing performance. In my opinion, your best bet would be to use a keyboard program running on a separate core, even an 8-bit one. Then you can forward the MIDI into the SEQ for note editing.

     

    The SEQ does have a step-edit (303ish) mode, but I think what you are describing is a different application, and one which you would have to program yourself. The current interface is very powerful and there are many layers for accents and so on. Notes can be added with a standard MIDI keyboard.

     

    It is great that you are thinking about something different and applicable to you, but if you say that this is your first project I suggest that you start with a basic SEQ build and see how that goes first. It would be possible to build an expansion later if you found the current interface too limiting.

     

     

     

     

     

     

     

     

  11. PCB prototype service?

    in Parts Questions

    Posted

    There was a thread a few years back discussing PCB proto services, perhaps it is time to revisit.

     

    I would like to hear about any user experiences, including things like price, quality, turn-around time, shipping costs and so on. I have found a few so far:

     

     

     

    http://oshpark.com/

     

    * USD5 per square inch, for 3 copies. Flat mailer is USD8 worldwide, shipping from US. Directly parses EAGLE files and quality looks high (ENIG).

     

     

     

    http://www.elecrow.com/

     

    * 5cm * 5cm USD9.9 / 5cm * 10cm  USD23.9 / 10cm * 10cm USD23.9, 10 copies. ENIG more expensive, but you can choose a PCB colour for free.

     

     

     

    http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html

     

    * Basically the same pricing structure as above, more for colours

     

     

     

    http://www.seeedstudio.com/depot/fusion-pcb-service-2-layers-p-835.html?cPath=185

     

    * Again, similar pricing structure (5*5 cm USD10, 10*10 cm USD25). Free shipping is available for orders over $50, you can combine with components or Arduino etc.

     

     

     

  12. MB6582 with Mean Well RPT-60B Switching PSU

    in MIDIbox SID

    Posted · Edited by latigid on

    You can buy triple output PSU modules from Mouser but then you will need to enclose them. I bought the MeanWell P25A14E for +5/+15/-15, I haven't hooked up the 15V rails yet but I hope to power the AOUT_NG inside my SEQ at some point. 

     

    Regulators have a certain voltage drop to contend with, which makes using a LM805 with a +5 V regulator edit: switching power supply impossible. Okay if your voltage is slightly higher.

  23. CV/Gate Breakout/Buffer Board

    in Design Concepts

    Posted

    Hi, I haven't routed a board before, so I would appreciate any advice! The top ground plane has been omitted for clarity.

     

    Seeing as I am using an AOUT_NG, my design has the same dimensions and mounting holes. I would stack the AOUT on top of this one with M/F standoffs.

     

    The eight analogue outs and gates are brought out to a DB-25 connector. The gates are either buffered or amplified to approximately 12V, selectable via jumpers. I am using a 100k/71.5k voltage divider for approximately 2.4x gain. At a 15V supply a 100k/50k combination would provide a gain of 3. One could also mount a variable resistor instead of the jumpers for more control. This works on paper, but I am wondering if the op amp will swing right up to its rails? 

     

    There is a spare buffer for the DIN sync/start connections also. I haven't figured out libraries in Eagle yet so some of the parts aren't quite right. <<Hmm, they probably need current-limiting resistors too....>>

     

    I am not sure how to power things inside my SEQ yet. Building a linear triple output PSU looks to be the best, but I may try a switch- mode unit. In this case power would be supplied at J1 and a daisy chain output is at J15 on the right-hand side.

     

    Perhaps it isn't quite the right thing to do, but I have isolated the grounds for the AOUT and gate signals. The ground for the gates can be tied to the same ground as the AOUT signals.

     

    Lastly, I have included pins for a DC-DC converter in case the SPSU doesn't work out. The two footprints on the top left of the board are for the muRata NMV0512SC and the Recom RS-0512D. It might be wise to include an inductor-capacitor circuit which can supposedly reduce the ripple voltage down to 5 Vpp.

     

    Thanks for looking and please share your thoughts!

     

     

     
     
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