46 episodes

A (mostly un-cohosted) podcast where we talk about progress - or lack thereof - of hobby-projects, mostly related to software, electronics or mechanical engineering.

CBA Podcast Michai Ramakers

    • Technologie

A (mostly un-cohosted) podcast where we talk about progress - or lack thereof - of hobby-projects, mostly related to software, electronics or mechanical engineering.

    episode 45: glucometer, fuel consumption and vacuum cleaner

    episode 45: glucometer, fuel consumption and vacuum cleaner

    (Michai is too lazy to make shownotes now, check again later. :-)

    • 31 min
    DMX512, ground reference and LED decoration stuff

    DMX512, ground reference and LED decoration stuff

    Hi, and an extremely good 2021 to all of you.
    We start off this brand new year talking about some totally unrelated and slightly more related new year's resolutions,
    a miniscule car fix, and glueing with a 3D printing pen. All in not much more detail than stated here.
    Continuing on last episode's VGA generator board, I added a DMX512 interface as suggested by some people - thank you for
    the idea. I found Q Light Controller Plus (qlcplus) a nice and so far solid piece of software for controlling DMX devices
    from a laptop + USB/RS485 converter cable.
    A potential issue (or at least in my head) when making interlinked devices like these, is potentially different ground-potentials
    depending on which power outlets you use to power networked your device. (See what I did there?) We talk a bit about how to guesstimate
    the possible magnitude of this difference.
    Just for fun I made an xmas LED star-shaped decoration using an existing DIY LED driver board. Reuse everything, recycle success.
    Also, made a modular transparant acrylic home LED decoration: shine light into the edge of an engraved piece of acrylic. Of course
    there was failure, this time in the form of hygroscopic LEDs + laziness + oven = damage.
    Finally, I made a small power switch PCB, to be placed in between USB power source and USB device: automatically switch the device off
    when the environment goes dark.
    And remember: if YOU want to make this podcast suck less, please send comments, rants, complaints, threats and/or praise. :-)
     
    Relevant links:
    Generic info on stray garbage and some cleanup initiatives (or Dutch version). Q Light Controller Plus : software for controlling DMX512 devices. The USB-to-RS485 cable I happen to use: USB-RS485-WE. Video of DMX512 VGA generator in action Tweet (*sigh*...) of star-shaped LED xmas decoration. Another tweet (*groan*...) of engraved acrylic LED decoration.   
    Pics of things talked about:
     

    DMX512 VGA generator boards.
     

    Engraved acrylic LED decoration PCB in action.
     

    ...in its base, open...
     

    ...and closed up.
     

    LDR USB power switch board...
     

    ...and schematic.

    • 24 min
    DMM probes, laundry fix and light-hangout

    DMM probes, laundry fix and light-hangout

    Welcome to a pretty boring episode - just as you're used to by now!
    Prepare yourself for epic or less epic talk about a mains test jig that proved very useful, some awesome Probe Master DMM probes well worth the money, and both me and occasional cohost Domen fixing household stuff, and the subtle psychology of starting a repair.
    Homebrew-wise, the only thing I made was a smooth green LED under-plant decoration. For fun, I visited an informal light-art hangout and talked about adding DMX512 to my VGA generator board. 
    Relevant links:
    a potato quality animated GIF of the green plant-decoration LED thing (on Twitter) the Probe Master DMM probes that I got - they are excellent Wikipedia's entry on DMX512 stage-gear control network Pics of things discussed:

    The test-jig from episode 41.
     

    Clumsily made LED strip using paper, glue and cursewords...
     

    ...and a simple PWM/MOSFET driver to control 3 such strips.
     

    Let there be Light, and let there be a Plant!
     

    Domen's epic Fireplace Fix: worn out film cap.
     

    • 11 min
    exploding cap, 3D-printing and planet decoration

    exploding cap, 3D-printing and planet decoration

    The thrilling tale of 4 months of doing pretty much nothing interesting is coming to a podcast near you today!
    After hearing about the hilarious exploding electrolytic, we continue with some lame or slightly-less-lame tools one can just buy off-the-shelf: using H-field probes for injecting magnetic fields into a PCB, the Aim-TTi I-prober 520 for measuring magnetic fields and current, and a simple but superhandy USB power meter.
    (I guess it's just a matter of time before all this deteriorates into an unboxing-podcast...)
    Various IRL events were canceled, so a YT livestream from a friend of mine got me thinking about 3D printing again. I settled on using a commercial 3D printing-service instead of DIY, and that suits me fine for now. This episode lists some criteria that may help you trying to decide between using a printing-service or getting your own printer, and if so, which printing-method suits you best.
    Lo and behold, I actually made something as well: a LED planet decoration thing using 3D printed "planet" and acrylic rings around it, that light up when LEDs shine onto them. For simulating visual effects, I tried and liked the Cairo 2D graphics library (for C).
    Links in order of appearance:
    product page about Beehive EMC probes Aim-TTi I-prober 520: product page and reviews on EEVblog or Mike's Electric Stuff (YT) one minute of PCB reflow inside my vapour phase oven And some fluffy pics:

    QCAD: 2D cross section of planet decoration's "planet sphere". The shape itself, and dimensions therein ("A", "B" etc.) can be read and used by OpenSCAD (3D) for extrusion. Pretty cool.
     

    OpenSCAD: extruded 3D shape, resulting from rotating the 2D cross section 360 degrees.
     

    A transparent engraved disk of acrylic fits between the 2 halves of the sphere.
     

    Planet decoration in action. 
     

    (laptop shown, to get an impression of the size of the decoration)
     

    A piece of LEDstrip sitting snugly inside the bottom half of the planet-sphere in the center, shining outwards into the transparent acrylic sheet.
     

    LED driver, old board with flaws...
     

    ...and new version, with fewer flaws.
     

    You DESERVE one of these if you make USB-powered crap. 
     

    Shoot your zapper at uranus! A dirty mind is a joy forever, and so is having a NES.
     

    • 17 min
    oversized test-jig, spiky LED ball and knowing your equipment

    oversized test-jig, spiky LED ball and knowing your equipment

    In this time of global turmoil, the CBA Podcast once again proves to be your one-stop source of distraction and meh-grade information.
    We start off by a quick list of how to keep busy in a sort of useful way, followed by a short talk about a 230 Vac test-jig and designing for test-jig repairability.
    Already mentioned in a previous episode, I finally got around to building a digital driver box consisting of push/pull FET and open-drain drivers for a low-voltage digital input-signal. And that's not the only thing that got finished: I also got around to make mechanics and software for a spiky icicle LED ball decoration thing, which worked out quite well.
    A fuzzy talk about getting to know your electronics equipment more intimately concludes this episode. If you are looking for useful things to do there, perhaps this is worth a shot.
    Relevant links:
    the ongoing RetroChallenge 2020/04 lasts until May, and is now hosted by Mark Sherman please leave 5G towers alone, and instead read Wikipedia's article on wireless device radiation and health some podcasts I listen(ed) to, in random order: Eaten By A Grue (Carrington Vanston & Kevin Savetz), about Infocom text adventures (even if you never play(ed) those, like myself) DoubleTake (Carrington Vanston & Shari Creamer), where 2 people review 1 mystery movie each Henry & Heidi Podcast (Henry Rollins & Heidi May), true stories from the past. Most have to do with music/punkrock, but probably accessible if you're not 100% into that. SledgeCast (Gerry something and Iain something), talking about "Sledge Hammer!" TV-episodes, one each episode. I binge-listened to these while driving to Hannover and back. The Amp Hour (Dave Jones & Chris Gammell), about electronic engineering. Occasionally have interviews that go off on a tangent, which I  like. Rationally Speaking (Julia Galef), about the borderlands between reason and nonsense (unquote). For some reason I can't listen to this while driving, but while walking on a treadmill everything's fine. Go figure. Damn Interesting Podcasts (Alan Bellows), true stories, told in fitting atmosphere. Creepy. Weird. Retro Computing Roundtable (Paul Hagstrom, Earl Evans, Carrington Vanston, Michael Mulhern, etc etc) about retrocomputing Welcome to Night Vale (Joseph Fink, Jeffrey Cranor and others), imaginary weird reports about an imaginary desert town. Recommended to me, I like it, haven't heard more than the first few episodes, and as with Rationally Speaking, I can't seem to listen to this while driving. :-) Joe Rogan Experience (Joe Rogan and guests). Sit down for an hour or two to get to hear about people you might not even have considered otherwise. Or skip to the next episode, of course. You Don't Know Flack (Rob O'Hara), telling stories about his own life. This guy can really tell a story, very funny and entertaining, even if you're not really into the subject at hand. Multiple Sadness (Rob O'Hara), about B-movies that are so bad they're good. Very funny and entertaining.  video of my LED icicle spike ball decoration on YT video of Pintek DP-25 differential probe weirdness on YT Some pics of the things mentioned in this episode:

    230 Vac test-jig, using DIN-rail components and a big block of MDF wood

    digital driver/amplifier box, innards

    LED icicle ball, innards. The small PCB is an AVR micro and 2 16-channel constant current LED-drivers.

    painted with acrylic paint and spraypaint. Should probably just have 3D-printed this in the first place...

    LED icicle ball, full brightness, sitting on desk
     
     

    • 18 min
    xmas smoothness, deadlifts and resistive load

    xmas smoothness, deadlifts and resistive load

    Welcome to the first and so far best episode of 2020, the third year of this podcast. Thanks for sticking around and making this happen, or alternatively, thanks for just tuning in - hope you like it.
    After a quick word on hot glue applied to mains wires, yours truly talks about being surprised by a SOT23 500V constant current driver (BPS BP9918C) in an LED lightbulb.
    Super-exciting, all of this.
    A cheap RGB LED strip decoration revealed a 5-24V LED driver (Greeled Electronic Ltd SM16703P) as higher voltage drop-in replacement for e.g. WS2811.
    Apparently not all christmas magic is done with those newfangled LED things - oldskool still has its place in an incandescent light decoration with smooooth ramp up/down effect.
    Perhaps being of more practical use, we talk about how the body converts food energy into mechanical energy, and show that exercising for the sake of losing weight is not the best approach. #spoiler
    Projects I actually worked on or even - *gasp* - completed, are a double pole mains switch, an ongoing hack including driver board for an LED icicle decoration, and a big clunky resistive load that also turns out to be inductive. (Turns. Windings. Inductive. Get it?)
    Links to relevant stuff (links to datasheets are probably volatile):
    BPS BP9918C datasheet (SOT23 constant current 500 V LED driver) Greeled Electronic Ltd SM16703P datasheet (3x 5-24V PWM serial constant current LED controller) article on energy needed for some weightlifting exercises by John Garhammer Wikipedia's Food Energy page Pic of hot glue ghetto-enclosure:

    BPS BP9918C example circuit:

    Double pole mains switch:


    32-channel LED driver board (30x30 mm):

    Resistive load:


     
     
     

    • 25 min

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