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jojjelito

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Posts posted by jojjelito

  2. [WTB] Waldorf Knobs

    in Fleamarket

    Posted · Edited by olga42

    I'm late to the party, phew!

    If this should come to pass I would be interested in 60 transparent knobs, and 30 red/black ones.

    Edit: The picture of the 6582 with transparent knobs looks like teh sex!

    Cheers :sorcerer:

    /J

  4. MB-6582 toasted?

    in MIDIbox SID

    Posted

    I dont have real experience with a Switching Powersupply. Does it help to remove the noise to put it in front of a 7805?

    The theory would be that the switcher can output some 7.1-7.5 VDC. The heat dissipation is very small, and the capacitors used by the 7805 plus the regulation of the 7805 will somewhat smooth out the 60kHz switching noise that this particular switcher emits at its' switching frequency. The switcher data sheet also lists a variant with lower noise using an extra, small inductor attached to the output.

    Add a garden variety 60kHz filter before the input of the 7805 and we're golden. Also, there is a good trick in AoE by Horowitz/Hill where they insert a 4001 diode (which is strictly for output polarity protection) between Vout and Vadj in parallel with a small resistor, 10uF to GND and a 5k trimmer to GND for improved ripple rejection. It's on page 386 in the 2nd edition, but I'm too lazy to draw up a complete schematic at this late hour :sleep:

    It's not impossible to come up with a low-noise switcher as long as you know what you're doing and can tolerate the somewhat higher component count. Hint, commercial switching PSUs are normally optimized for cost, thus low component count and therefore they are :nuke: I used the AoE trick above for a very low noise toroid/LM317/337 solution that has good performance at a low component count. The switcher is the research part here.

    I'm about to slap the above together as an alternative to a seriously old c64 PSU in any event, so I'll report my impressions in due time.

  5. MB-6582 toasted?

    in MIDIbox SID

    Posted

    I don't mind contributing by designing something which would benefit more people.

    However if we want to make a propper design: 1 x 5VDC 1 x 9VDC 1 x 12VDC 1 x -12VDC you have a couple of options:



    2. Using multiple transformers
    3. Using a toroid transformer with multiple secundairy voltages
    4. Use a 12VAC transformer and put some big resistors in front of the 5V and 9V regulators Less desirable

    Problem with option:



    2. Needs a lot of space
    3. Hard to find
    4. Lots of heat dispensation

    My prefered option would be 2. But so far i haven't found the propper toriod transformer yet. So if someone knows a good part for this.....

    Hmm, what about getting a 9VAC toroid and use a LM2576-5 switcher, or use an LM2575t-adj as a pre-regulator to a vanilla 7805?

    Less heat and not exactly a very noisy switcher.

    In order to get to 12VDC we can use a LM2588 or a similar contraption. Or go with a dual, say 12/9VAC toroid?

    Any thoughts?

  7. Midibox CV features available?

    in MIDIbox SEQ

    Posted

    Since I need such options as well, I will add a special CV configuration menu soon.

    Best Regards, Thorsten.

    Thank you and cheers!

    I had a hunch it might come, but I had to check so I didn't start some parallel hacking :poke:

    This will be interesting, a USB/Ethernet sequencer with SD-card storage containing a now beefy octal MIDI-CV converter! It's ultra-modern and retro in one box. Trip the light fantastic!

    Kind regards,

    Johan

  8. Pactec PT-10 seller from germany PBE electronic

    in MIDIbox SID

    Posted

    Was looking around on the net to get a PT-10 enclosure shipped to my adress. I found a german seller.

    I was wondering if anyone knows this seller and if the shipments are done on time and correct. Especially when shipped outside germany.

    http://www.pbe-shop.de/shop/448.html

    grtz

    Nicely spotted! I was using xoxshop.de last time I needed a PT-10, but this could save you a couple of Euros, depending on shipment costs.

    Can't vouch for PBE Shop yet, but xoxshop.de runs tight.

    Take care,

    J

  9. Midibox CV features available?

    in MIDIbox SEQ

    Posted

    Buenas tardes!

    I have yet to experiment with the A_OUT and my SEQ_V4. However, I was taking a quick glance at the sauce code and wasn't able to spot some useful (to me at least) functions related to CV output: namely gate polarity, output curve and possibly interpolation. Then there's the issue of calibration. It's probable that I've missed something, or is just plain crazy or - just dreaming out loud.

    Have I missed something, or would I be free to add those to some Aout channel setup menu? My MS-10 says it wants to be connected :hug: The modular growls and purrs that it wants to make weird sounds under MB_SEQ control too. The match is entirely seemly.

  10. 16bit octal A_out

    in Design Concepts

    Posted

    So far TDA1543, PCM1725 and PCM1754 have been successfully used :) Also, the stm32 has a 2-channel 12bit DAC on board that works pretty well (I am using that as an audio out for the sid emulation).

    Yes, me with the kaffeSEQ :)

    I guess we're pretty well covered in the stereo 16-bit area :sorcerer: Then there's only the mythical quest of finding a decently accurate multi-channel solution for VCOs without resorting to PCM1680 ΔΣ-type devices. Or be happy with 12bits since it's analog with some inherent instability and therefore we don't worry too much about precision...

    Gotta read up more on the I2S synth instead of just browsing the repository one of these days. Plus check what the kaffeSEQ is doing. Sounds like replacing filter, grinding beans, heating water, pumping and... STOP daydreaming!

  11. 16bit octal A_out

    in Design Concepts

    Posted

    Mmm, figures... Since I was already under the impression that the performance benefit was marginal at best I guess this one was killed in the bud :whistle: With some luck we'll find better alternatives for higher precision later on. The deal with 16-bit for me is in VCO control and in direct wavetable synthesis if one is so inclined. The added precision does nothing for VCF/VCA etc control. Maybe there's some I2S-alternative out there?

    As for the homemade board this was intended just for experimentation and hardware-bringup. Once the driver is done and preliminary performance data obtained with my trusty Tektronix then it would be time for a proper board. Noise issues and layout tricks will be far more critical with these multibit monsters.

    Summing it up: 12-bits it is for now. TSSOP vs SOIC is not going to go away, unfortunately. If you can mod a PS2 then you'll be fine with TSSOP. I'll be surprised to see anything but bump-grid (BGA) nastyness a few years down the road for mass-market applications. Then we DIY peeps will be SOL. I guess more cards will go with pre-soldered bits and pieces.

    - PIC core, is anyone using those for new MIDIbox projects? Not to knock them, but where's the USB firmware download on those old things :frantics: It's been a good ride with MIOS8, but times are changing.

    Thanks Seppo!

    /J

  12. 16bit octal A_out

    in Design Concepts

    Posted

    Are you saying either of these chips can substitute for the DAC in the AOUT_NG? What makes "worst case" such that only 12 bits are honored? This sounds like a worthy line of investigation. I have one of the first generation of AOUT boards that'll eventually be used to interface to some analogue stuff. Maybe it's time for me to get an AOUT_NG board.

    Haha, unfortunately they're not pin-compatible with the TLV5630 used in the AOUT_NG :tongue: That would have been too convenient for someone else to not have noticed already. There are two families from TI and AD who just happen to share the same pinning, characteristics etc which the two chips are part of. I was planning to investigate an AOUT_16 if there is some additional performance/precision to be had, but it will require new boards with a redesigned footer for these chips. I'll whip something up for kitchen etching for myself at first :ninja: Then I'll have some fun with a couple of VCOs in the form of a couple of different CEM chips and a discrete transistor thingy from the bakelite, metal and wooden end cheeks-era.

    When I was quickly skimming the datasheets I saw that the relative accuracy is 4 bits LSB of the TI DAC. The AD DAC also comes with some inherent INL error, but you're bound to see those on any DAC.

  13. 16bit octal A_out

    in Design Concepts

    Posted

    I was investigating DACs due to circumstances involving analog synthesis and came across the pin-compatible DAC8568 (octal 16-bit DAC, 10uS settling time at worst) and the AD5668 with similar characteristics. It looks like any of these two could be mounted on a PCB in order to attain 16-bit resolution with hopefully better precision than the current Aout_NG (which isn't that bad!). The datasheets don't guarantee better than 12-bits resolution at worst case but at 14.81€ (Digikey) for the AD, and at 22€ (Mouser) for the TI DAC it's not worlds apart from the TLV5630 at 18.13€ (Mouser).

    I was thinking of getting a couple of each in order to do some experiments. Any thoughts about the worse settling time, or if this endeavor would be at all worthwhile? I was thinking it could be fun to write a SPI driver for these 2 ICs in the long, dark of fall.

    Cheers!

  15. SDcard Types?

    in Parts Questions

    Posted · Edited by olga42

    As per Wikipedia there are also references to the old way of using 1.2Mbps as the base for x-speeds. Somewhere in the Wiki it is stated that you should get a card that is safe for 100x, or 15MB/s write speed so that MB_seq can write data while still operating in real time. I think it sounds a bit demanding, but I found some nice 4GB SDHC cards that were ok for less than 20 USD so there's no need to skimp on the cards.

    Please note that the amount of data you'll likely write is very small (a few MBs or so), and that 4GB is the absolute maximum amount that can be addressed. MB_seq doesn't do exFAT or any such tricks used to address higher capacity SDHC or SDXC cards.

  16. MBHP_ETH, MBHP_SDCARD, SSM2044, SSM2164 PCB Bulk Order

    in Bulk Orders

    Posted · Edited by olga42

    yes, me :tongue:

    ...

    btw, don't ever "bypass", i.e. bridge/short, anything you don't really know why it's there ;)

    S

    Thanks Seppo!

    Haha, had this been pure analog or high-power pins I would have been really careful. You can get away with more in the digital realm :whistle:

    Official SD-card specs... *facepalm*, thought those were secret or proprietary so I didn't bother faffing around with those :fear: . DUH!

    *EDIT* 'Twas working fine yesterday. Before this I only had the standard I/O mapping, now I run the full Wilba version with my front panels. Now for some SSM fun...

    /J

  19. C++ Real Time Programming Safety/Style

    in MIOS programming (C)

    Posted

    Yarr!

    I see that the JSF guidelines references my old arch-enemy: The MISRA (misery) guidelines. So we meet again! Takes me back to when I was working as a programmer for a living... Then I de-evolved, ha-ha.

    Does anyone know of a good freeware alternative to PC-Lint by Gimpel? It still costs 389 bucks, so it's a bit steep for hobbyists. Sometimes a little static analysis is what the doctor ordered. There are of course plain vanilla Lint implementations but is there something more comprehensive which is still free? I did quickly check Wikipedia out of curiosity.

    Cheers!

  20. THAT IC cheap source

    in Parts Archive

    Posted

    farnell seems to have them. not cheap though

    Elfa has the SSM so I can walk there... Joking aside, Banzaieffects, Small Bear and Bridechamber all carry some of these.

    The SSM is compatible with THAT1646 or INA137. But, it seems you're stuck with Farnell, Mouser and perhaps Digikey amongst the bigger companies. RS/Allied only seem to carry some SSM's.

  21. Novelty drum-tone oscillator

    in Miscellaneous

    Posted

    oh maan i'll never forgive you!!!!!!!!1

    and i just sold my best friend Stu to the lab next door to be able to afford them sad.png

    post-5444-127014141603_thumb.jpg

    bummer

    Mmm, otherwise I know some hungry (traditional) Koreans in case the lab loses interest... He looks yummy enough for some Bulgogi :drool: ! BTW, the kitteh eated my protoboard, oh noes!

    Now, after the fun and games with the Core32 and the MB-seq v4 today, which did work on first attempt - yay, it's time for teabagging some noobs in BFBC2 (Schlachtfeld, schlechte Gesellschaft zwei) methinks :ninja:

    Happy Easter!

  22. Novelty drum-tone oscillator

    in Miscellaneous

    Posted

    Erm, today's date is? :D

    I'm sure my revolutionary drum oscillator has evaporated in a cloud of magic smoke by the 2nd of April. However, now that it almost did sound feasible I might axshually make something up later. Sound samples and all... :whistle:

    Toodles!

  23. Novelty drum-tone oscillator

    in Miscellaneous

    Posted

    Hi all,

    I was recently perusing a few old drum oscillator circuits in order to figure out a radical modification to my TR-9090. I came across a good explanation of how the classic twin-T oscillator works at PAIA.

    I wanted to make it down with the kids these days, so this variant of the twin-T is now the Teabagging oscillator. By adding a simple comparator that checks the CV level at R3 in the PAIA schematic we can tweak gliss behaviour over time. Thus, when the CV voltage has died sufficiently we can humiliate the circuit by adding fresh voltage through the comparator. This, leads to the drum sound being manipulated in novel and interesting ways.

    Schematics might follow at a later date. If you are nice I might even produce tiny PCBs with Ponoko-made boxes for all the cool kids.

    Cheers y'all!

    :sorcerer:

  25. MBSeq 19" panels

    in Fleamarket

    Posted · Edited by olga42

    ok Julien, will do in the morning.

    So, one remains.

    Julian

    PM Sent! I'll take the other plus some extra bits and bobs.

    Monday the 8th of March:

    I received my panel from the friendly postman this morning! So, I spent the evening glueing on standoffs and fixing the PCB to the panel. It was dead easy and looked the business. The craftsmanship of the cut panel was second to none.

    Big thanks to Julian!

    /J

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