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Wilba

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Posts posted by Wilba

  1. Genuine THRU circuit needed for this?

    in Design Concepts

    Posted

    Since MIDI works via a current loop, splitting the MIDI Out at the SOCKET probably won't work very well, both receivers would be sharing the current, and the optocouplers would get half the current or one would rob the other or some other weirdness... can't be sure exactly.

    It would be best to add a buffer (logic gate), fed from the point driving the MIDI Out... in a MIDIbox "Core" this would be the Tx pin of the PIC, between the 220 ohm resistor and the MIDI Out pin. Then the output of the buffer goes to 220 ohm resistor to the replicated MIDI Out socket. Remember that as the signal is high and low, it is sinking current from the other MIDI Out pin (connected to 5V via 220R), out the cable, through the receiving end, returning back in along the cable to the MIDI Out pin. So you replicate this bit too around the buffer.

    I have actually tried this with just a BC557 instead of a buffer (made a MIDI Thru by connecting BC557 to Rx pin of PIC).

    So unless you are planning to switch between the two, you do need some kind of buffer... or at least tap directly to the Tx pin or whatever is driving the MIDI and replicate the whole 5V->220R->socket->220R->Tx pin arrangement.

  2. Genuine THRU circuit needed for this?

    in Design Concepts

    Posted

    Perhaps the easiest solution is to add a switch between the AX's MIDI Out pins and the MIDI cable to the Widi-X8.

    As I see it, your use cases are mutually exclusive, you never want to use both MIDI Out socket AND Widi-X8 at the same time. So use a switch with a double pole. Connect the two switch "pole" pins to the AX's MIDI Out socket pins (easy to do, just solder to the PCB pads!), connect the two switch "throw" pins to the cable/MIDI plug going to the Widi-X8. Thus the switch will enable/disable the connection to the Widi-X8, the AX's MIDI Out socket will always be wired, but without a cable connected, it can't affect the Widi-8, since MIDI cables work by a current loop.

  8. Non conductive heat sink compound

    in Parts Questions

    Posted

    It's preferred to solder the voltage regulators after attaching to the heatsinks/PCB via screws and then never moving it again. You could solder them without compound, but then you would need to bend the leads to apply it later. Not such a good idea, as bending it back might not result in as good a mating between the voltage regulator and the heatsink (i.e. not be as parallel).

    As much as I love PCBs with plated through holes and pads on both sides, I hate desoldering such pads, especially ground plane pads... so my attitude is perhaps different... I solder things with the intention to do it once and not touch it again. So the idea of even temporarily soldering voltage regulators and then desoldering later to do it properly with compound etc. just makes me cringe.

  10. 4X20 OLED display (event. for MB6582)

    in Bulk Orders

    Posted

    See what you can get, PM me with details.

    They are listed as "yellow-green" same as my dead one. They are green enough to match with "green" LEDs since most "green" LEDs in tinted green diffused packages (like what I sell) are actually "yellow-green". You can get superbright/ultrabright "true green" in waterclear or white diffused packages, on eBay for example.

  12. 4X20 OLED display (event. for MB6582)

    in Bulk Orders

    Posted

    Necro bump!

    I see your necro bump and raise you an obscenely large JPEG.

    5686333383_74d2119e04_o.jpg

    MB-6582 prototype

    I have plenty of those little PCBs that go above the LCD (at top and bottom). I probably have spares of the shorter switches you need to mount on them.

    It should be relatively easy to convert the production MB-6582 CS PCB to use these extra PCBs for the switches. The pads to connect them are on the PCB, to support such usage.

    WARNING! DO NOT STARE AT THE BLUE LEDS! YOU WILL GO BLIND!

  14. Non conductive heat sink compound

    in Parts Questions

    Posted

    I think he means is heat transfer compound (of any kind) necessary, and I would answer no, it will work without it, just like a car will work without radiator coolant. (Yes, I'm being intentionally metaphorical).

    On a sidenote: Futurlec sucks. Even if you do get your order, it's mostly the absolute cheapest crap you could get. i.e. something might look like a Neutrik socket but be plated from stuff which will tarnish in a year and/or give you bad solder joints. If I knew years ago what I know now, I'd just pay the premium (of fixed $30 international postage) and get the good stuff from Mouser or Digikey, which have cheap prices anyway compared to local electronic stores.

  21. sammichFM behaving oddly **FIXED**

    in MIDIbox FM

    Posted

    LOL

    At least you got to do some troubleshooting... I've not needed to on any board I've soldered myself in a long time... which is slightly boring. I don't even bother with voltage tests before plugging in ICs just hoping for a fried IC to locate and replace. *sigh* I suppose it's a good thing because troubleshooting aka. debugging aka. software development is my day job.

    The last time I had some head-scratching WTF moments was with the OPL3 module:

    Comment #7 is lulzworthy though.

    BTW that OPL3 module is totally redundant now. Free to a good home, inc. free shipping.

  23. Sammich SID Power Supply Queries

    in MIDIbox User Projects

    Posted

    a) Polarity doesn't matter if you are NOT bypassing the bridge rectifier via headers JBP. However, if you are using a regulated DC power supply that is tip positive, you can optionally bypass the bridge rectifier (like you must for 6581 use) so you get 12V DC going into the 9V regulator.

    b) 12V is OK. I use either a 12V AC 500mA or a regulated 12V DC. It should work fine.

    c) Of those two choices, I would not choose the 2nd one because it is switchmode. The 1st one will work and is preferred because it is regulated and appears not to be switchmode. Switchmode power supplies typically have an input voltage range (like 100V-240V) and aren't so chunky. Also it's confirmed "linear" in the questions tab on that page. You might need to use shunts in JBP as mentioned above, but probably won't... 12V - 1.2V (drop of 2 diodes in brige) = 10.8 V, should be enough for 7809. YMMV.

    Please update the wiki with a link to this one if it works well for you: http://www.midibox.org/dokuwiki/sammichsid

  25. sammichFM behaving oddly **FIXED**

    in MIDIbox FM

    Posted

    Try swapping the PIC with another one. Scratch it with the knife first to clearly mark it as suspect #1.

    (Note to other builders: I can suggest this to him cos I know he has lotsa sammiches)

    The "every nth patch doesn't get uploaded" could be due to too short time between SysEx blocks, try increasing this to some magic number which I can't remember, but mine is set to 1000ms which is overkill.

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