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latigid on

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Posts posted by latigid on

  3. Question about analog oscillators

    in Miscellaneous

    Posted

    Oscillators are not inherently unstable, but our hearing means we perceive pitch exponentially. So from one octave to the next means a doubling in frequency. If you want to control pitch on a VCO linearly (commonly 1 volt per octave), then you need an exponential converter for your keyboard or MIDI data. Most of these circuits have a temperature coefficient that is always present.

    Digital oscillators just count a number of divisions of the master clock. Quartz resonates at a very specific frequency, and so it's much easier to count pulses this way. I think the SID uses a lookup table to derive the oscillator frequency.

  9. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    large.5958cbf9a8d8c_leMEC_rear.png.24794

     

    LEDs are nice and bright; this is from the rear side! I'll need some help/fiddling with the switch portion as this is not a 1:1 BLM.

     

    I noticed a similar concept from 40%club:
    http://www.40percent.club/2017/06/alps-48-rgb.html

    I considered mounting 5050 LEDs in this way last year, but IMO the available ones are not really bright enough. As well, I'm not sure how reliable a "bridge-soldered" LED would be in the long run after a lot of keypresses.

    c1.JPG

     

     

     

  11. Old music

    in Songs & Sounds

    Posted

    A little while ago I found my collection of mp3s I made with my band about 10 years ago. Everything is LoFi with distortion and dropouts as the jams were recorded onto a dynamic mic and then cassette tape, then transferred to the computer. No processing in post, mistakes not fixed, no song titles, just the code of the tape and a few descriptors. The mixes are often off, and these were just recorded as they come, so can be quite long-winded. But I still find them quite cool.

    Synths/keys used are Moog Voyager, Rhodes '73, Rhodes Chroma, a couple with MS-20. Sherman Filterbank, RE-150 Space Echo and Moogerfooger effects. I play bass on a couple.

    You'll probably like the "jungle" drum and bass drums (all live), and there's some vocals too. The singer probably prefers that his levels are low :).

    Can't be bothered with Soundcloud/youtube at the moment, so I'll post links to dropbox.

    https://www.dropbox.com/s/gtfo0yzb86lr7wq/65A%20distorted%20fedback%20db.mp3?dl=0
    I think the delay used here is a Boss DM-300, a 4096 cell BBD. The input is overdriving which gives some very crunchy sounds on the Rhodes. 

    If anyone likes, I can post the longer ones which go up to +20 minutes continuous. Mostly it's dub/drum'n'bass style but there are some different ones too.

    Best,
    Andy

     

  12. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    For those playing at home, there's a delay on Matias switches, apparently as they are producing a newer design with "reduced key wobble." I didn't think the wobble was too bad, but there you go. The restock is due at the end of August. In the meantime I will try to test things without switches and also look at an order of keycaps.

  14. Could 10cm cables between the MB_6582 mainboard and the CS board be too long?

    in MIDIbox SID

    Posted

    Should be okay. With a matrix design, you usually get entire rows or columns out rather than a few here and there.

    One thing I've noticed, is that the through hole plating is not always the best. For LEDs and switches that don't work, try soldering on both sides of the joint, adding flux if you need to. You have to be careful of melting any plastic components, and also e.g. soldering LED legs one at a time so the alignment stays good.

  18. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    2 hours ago, jarvis said:

    My main concern with the design is that, at least according to the renderings, the data wheel is not flush with the surface of the case.

    The idea uses a DK-38 knob from ALBS, and I've asked Adrian to accommodate for it by cutting a hole in the front panel. So it will already be sunken down a bit. But no, it's not flush with the panel. They also have a fairly long stem, which is why the wheel on the Wilba version is "panel mounted" to the PCB.

    Do you know of a datawheel knob that sits lower? Please tell me a part number and I'll have a look.

     

    2 hours ago, jarvis said:

    I would expect this to lead to accidental knob nudges when pressing the frequently used function buttons surrounding it,

    The suggested encoders are 24ppr/24 detent, so you'd need to turn the knob 15 degrees to register a click (or is it half that with the fast encoder scanning?). Doing a bit of maths says you'd have to turn the outside (least torque required) almost 5mm.

     

    2 hours ago, jarvis said:

    or at least make some of the ergonomics a little odd since you have to angle your finger around the edge of the data wheel.

    Unless you have tiny Trump hands, you should have more than enough room to reach all of the buttons without bumping into the encoder. The usage is not 100% clear, but it's possible that the wheel and buttons will be used together quite frequently. 

     

    2 hours ago, jarvis said:

    Is there other hardware you've modeled this layout after?

    It's mostly original and aims to use the remaining space left over from the LCDs/OLEDs. But perhaps something like this:

    shuttle.thumb.PNG.5952d9709f61a5c01ac845

     

     

  19. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    Hi,

    We might have to move the discussion soon, but what the hey. :happy:

    Yes, the Waveshare boards look good and are much smaller than the Discos. There are some others which have an even better arrangement (mounting holes and top-mounted header pins), but on the face of it Waveshare look a bit more trustworthy. Still have to find time to test!

    The downside is exactly that: no STLINK onboard. It could be possible to flash on UART0 (I think), but you still need a USB-UART converter.

    I bought something like the following:

    http://www.ebay.com/itm/ST-Link-V2-Compatible-STM8-STM32-Programmer-with-4-Spring-Loaded-Pogo-Pins-/201303925381

    but if you have a Disco board it should also work to connect using the normally jumpered header pins on the ST-link side.

    The USB module optimally aligns close to the Core on a 5 pin header, but it could be placed further away if needed. A main reason for moving to another carrier is that the USB MCU pins are on the header, so no more flaky microUSB! The host/slave switch is probably not proper USB spec, but should be okay for DIY purposes. The SD card sits on another PCB underneath (J16E), with the LEDs and reset button. Hopefully that's okay given the lack of power switch. I didn't put one in because it would've complicated the USB spec (should apply power prior to data pins).

  22. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    Perhaps a few teaser pics:

    20170530_234712.thumb.jpg.c3001265d01397

    Closeup of the wCore, note the USB/SD "modules" above:
    20170530_234744.thumb.jpg.94284546d951f2

     

    One tricky thing was to mount an LED but not go beyond 160mm x dimension.

    This was the answer:
    20170530_235243.thumb.jpg.3869c2f4387125

     

    There was room on the back, so this is dedicated to the guy who loves the Beat LED:
    20170530_235330.thumb.jpg.7b48de9cacafb1

     

    A bit hard to capture the mask text, but it reads:

    "the big beat LED somehow belongs to a MIDIbox SEQ, it's like a defining feature :D"

     

    • Like 3

  23. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    The best thing is you can choose the keys you want:

    http://matias.ca/switches/

    The options like you say are click, quiet click or linear. I though I'd like the linear, but actually I prefer the quiet click. Some people enjoy clicky keys, so no worries there!

    PCBs are here, unfortunately they didn't do the cutouts for the LEDs, so there will be a delay in testing. 

    I also need to get some parts orders done -- getting there slowly!

  24. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    It's okay, I'm not offended. It's just unclear from your wording whether you were suggesting "You may want tio take a look at some of the matrix keyboard..." in a general sense or for this project. A few weeks ago you were asking for extra headers to use panel-mounted switches, so my initial sense was for the latter.

    Fact is they _are_ really cool hardware items, and they should definitely be incorporated into more projects. You might have seen Wilba's Cherry Jammer keyboard with a clever velocity sensing mechanism, or I think it's antichambre who was looking at reflectometric light sensors. 

    No DHL today, so another few days to wait at least. :(

  25. MIDIbox SEQ new frontpanel idea

    in MIDIbox SEQ

    Posted

    It's true that some of these layouts could be useful for other projects; I suppose they're somewhat related.

    It's also a different story doing "bespoke" builds rather than a repeatable project. For instance, the closer spacing means the caps must be cut down (or those custom clear caps, which don't look great IMO), and not everyone is prepared with the right tools.

    Another thing to consider is how the button layouts work with other hardware. 19mm standard spacing is actually perfect for a 40x2 LCD.

    Sorry, I'm not trying to be too grumpy. The PCBs were designed over a period of months with the whole build in mind, and the order was placed weeks ago, so it's not changing unless there's a problem with the prototypes :happy:

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