Signal Conditioning Hack Chat

Massage those signals

Wednesday, February 17, 2021 12:00 pm PST Local time zone:
Hack Chat
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Jonathan Foote will host the Hack Chat on Wednesday, February 17 at noon Pacific.

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The real world is a messy place, because very little in it stays in a static state for very long. Things are always moving, vibrating, heating up or cooling down, speeding up or slowing down, or even changing in ways that defy easy description. But these changes describe the world, and understanding and controlling these changes requires sensors that can translate them into usable signals -- "usable" being the key term.

Making a signal work for you usually requires some kind of signal processing -- perhaps an amplifier to boost a weak signal from a strain gauge, or a driver for a thermocouple. Whatever the case, pulling a useful signal that represents a real-world process from the background noise of all the other signals going on around it can be challenging, as can engineering systems that can do the job in sometimes harsh environments. Drivers, filters, amplifiers, and transmitters must all work together to get the clearest picture of what's going on in a system, lest bad data leads to bad decisions.

To help us understand the world of signal conditioning, Jonathan Foote will drop by the Hack Chat. You may remember Jonathan as the "recovering scientist" who did a great Remoticon talk on virtual modular synthesizers. It turns out that synths are just a sideline for Dr. Foote, who has a Ph.D. in Electrical Engineering and a ton of academic experience. He's a bit of a Renaissance man when it comes to areas of interest -- machine learning, audio analysis, robotics, and of course, signal processing. He'll share some insights on how to pull signals from the real world and put them to work.

  • Hack Chat Transcript, Part 2

    Dan Maloney02/17/2021 at 21:08 0 comments

    Kevin Andersen12:49 PM
    haha fair enough, maybe I should just try stuff out and see whether smoke appears

    Jon Foote12:50 PM
    Wow that sounds fun. Is an oil ignition xformer like a neon xformer?

    Jon Foote12:50 PM
    You could measure input current/power with a wattmeter, might that help?

    Jon Foote12:51 PM
    Not sure what the failure mode is.

    Johnathan Carlson12:51 PM
    more or less. It's just take 120 in, dump 10kv @ 22ma out. I think most of the neon sign ones do some sort of switchmode PSU voodoo, but this is a clasicall hunk o' copper transformer

    Jon Foote12:51 PM
    OK. Classical neon transformer is current iimited so you can short it out with no problem.

    Johnathan Carlson12:51 PM
    I mean, the transformer itself did try to start on fire one time

    For the curious:

    The Home Depot

    BECKETT Electronic Oil Igniter-51771U - The Home Depot

    Electronic Oil Igniter - Designed for efficient ignition. Vacuum encapsulation process. Adapts to multiple baseplates. Case material constructed of high-temperature thermoplastic. UL recognized in the

    Read this on The Home Depot

    This one is rated at only 6 kV

    Jon Foote12:52 PM
    Cool! I'd recommend an old-school neon xformer. They are tough and current limited using saturation of the core.

    I think the oil igniters are also somewhat duty-cycle limited. Neon signs are made to be on all day, OTOH

    Johnathan Carlson12:53 PM
    Hmm. That's good to know. The current limiting might be a smart move. I don't know that mine does or not (though it hasn't popped a breaker so ╮(─▽─)╭ )

    Jon Foote12:53 PM
    Can't beat the price of the oil thing though -- next time I need high voltage I will check it out :)

    Johnathan Carlson12:53 PM
    as an aside, 10kv though the arm is quite the experianec.

    Jon Foote12:54 PM
    Glad you are OK, yikes!

    Leigh L. Klotz, Jr.12:54 PM
    as long as it's not both arms

    Jon Foote12:54 PM
    In school woking on HV machinery

    morgan12:54 PM
    yyyeeeah, was going to ask where the other contact point was...

    Jon Foote12:54 PM
    we are under strict instruction to only use the dominant hand

    Jon Foote12:54 PM
    you put the other one in a back pocket so the current doesn't go through your heart

    Yeah, I took 32 kV from a TV flyback through the arm once. That was eye-opening.

    morgan12:55 PM
    HV scares me so I always single hand it

    Jon Foote12:55 PM
    15ma will kill ya. So worth playing it safe

    morgan12:55 PM
    (HV for me being anything above 12v :::))))

    Johnathan Carlson12:55 PM
    I believe it went in my right arm and out my right shoe, as both my right arm and right leg felt about the same tingly as when they 'fall asleep' but like 5x more intense.

    Jon Foote12:55 PM
    Wow glad you are OK.

    Yeah, but now I have superpowers ;-)

    Jon Foote12:56 PM

    Dave Blundell12:56 PM
    I got hit with the secondary side of an automotive ignition coil being fed by a CDI box on the primary side. It knocked me to the ground.

    Dave Blundell12:56 PM
    not fun.

    Dave Blundell12:56 PM
    ~40-50Kv, 2-3mJ ?

    Jon Foote12:56 PM

    Johnathan Carlson12:56 PM
    the lesson: Don't add water to the wood while the transformer is still on. It will arc up the droplets.

    Jon Foote12:57 PM

    morgan12:57 PM
    how no one got hit at Superconf 2 years ago still blows my mind

    Jon Foote12:57 PM
    I guess you can't use deionized water because you need a little conductivity>

    Jon Foote12:57 PM

    morgan12:57 PM
    so much arcing, so much beer

    Leigh L. Klotz, Jr.12:57 PM
    best not to trust the lumped circuit model with high voltage / high frequency

    Johnathan Carlson12:57 PM
    Yeah, the water actually has to have baking soda added to it.

    Jon Foote12:57 PM
    No longer a lump :)

    Jon Foote12:58 PM
    Interesting BM problem I helped with: Tim "Wizard" Black making flame speakers

    Jon Foote12:58 PM
    If you put ions in a flame it reacts to magnetic fields

    Jon Foote12:58 PM
    and you can make the flames speak

    Jon Foote12:59 PM
    so had to inject ions via a wick of electrolyte...

    Read more »

  • Hack Chat Transcript, Part 1

    Dan Maloney02/17/2021 at 21:07 0 comments

    Jon Foote11:57 AM
    Hello, this is Jon, hoping I'm in the right place!

    Indeed you are, welcome Jon!

    Jon Foote11:58 AM
    Thanks Dan, and thanks for putting this together.

    morgan11:59 AM
    hi Jon! long time, how's things?

    Jon Foote11:59 AM
    And thanks to @Aleksandar Bradic for the poster which is seriously DOPE

    Aleksandar Bradic11:59 AM
    ha :) thanks!

    OK folks, let's get started. Welcome to the Hack Chat, I'm Dan and I'll be moderating along with @Dusan Petrovic . We want to welcome Jonathan Foote to the channel today to talk about signal conditioning. TBH it was hard for us to settle on a topic because Jon has such a wide range of interests, but we figured this could be a fun topic that we haven't talked about much on the Chat before.

    Welcome Jon -- can you kick us off with a little about yourself?

    Dusan Petrovic12:00 PM
    Hello and welcome all!

    Jon Foote12:01 PM
    Sure! People ask me what I do and I say I'm a "recovering scientist"

    Jon Foote12:01 PM
    I played the academic game for a while after grad school -- I did a postdoc in Cambridge England

    Jon Foote12:01 PM
    Then I did a fellowship in Singapore

    Jon Foote12:02 PM
    The academic thing wasn't working out so well so I settled for a cushy job in industry

    Dave Blundell12:02 PM
    define "cushy" ?

    Jon Foote12:03 PM
    Sure -- as opposed to an academic gig which is like three jobs: teaching, service, publish or perish, a 9-5 counts as "cushy" lol

    Daniel Lynch joined the room.12:03 PM

    Jon Foote12:03 PM
    Huge respect to those in the professor biz it's a lot of work and scary because tenure is not a given

    Dave Blundell12:03 PM
    My little brother is trying to decide whether he wants to stay in academia after his doctorate or venture into the world. It's different, for sure.

    kalspelletich12:04 PM
    Jon, What are you excited about to work on>?

    Jon Foote12:04 PM
    So I did a lot of fun things at the researh lab (called FXPAL, FX=Fuji Xerox, kind of a PARC wannabe)

    Jon Foote12:04 PM
    Like using some the things I had worked on in grad school for speech recognition and analyzing music and video

    Jon Foote12:05 PM
    Some of the patents on those have run out so it may be time to look at those again :)

    Jon Foote12:05 PM
    On fun invention I called the "beat spectrum" which was a way of analyzing the tempo and rhythmic structure of music

    Jon Foote12:06 PM
    Hang on I will drop a link

    niel joined the room.12:06 PM

    Leigh L. Klotz, Jr. joined the room.12:06 PM

    Jon Foote12:06 PM


    Jonathan Foote Portfolio

    For a number of years I worked on an approach to analyze audio and video based on self-similarity. Comparing every part of a media file exhaustively with every other part results in a "similarity matrix" that both visualizes the time structure of the media and facilitates further analysis like segmentation or verse/chorus detection in popular music.

    Read this on Rotormind

    Leigh L. Klotz, Jr.12:06 PM
    Hey Jon - is this related to the viz work you did that I helped review?

    jeff joined the room.12:06 PM

    Jon Foote12:06 PM
    Hello, I see some names I recognize -- yes Leigh, it was

    Leigh L. Klotz, Jr.12:07 PM
    I was hoping so. I really enjoyed that and am here to see where you've taken it and your other signals work. Thanks for doing this!

    Johnathan Carlson12:07 PM
    Hey Jon. I know you did a VCV hackchat before and mentioning the Beat Spectrum project there- is music and synthesis your main focus?

    Jon Foote12:07 PM
    So after my time at the research lab I took a year off to do some less-formal work (among other things working with artists like @kalspelletich

    Jon Foote12:08 PM
    ANd I did some consulting to pay the rent, and 15 years later I'm still doing the same thing, so I've failed to both specialize and get back on the hamster wheel

    M joined the room.12:08 PM

    smatterchoo joined the room.12:09 PM

    Johnathan Carlson12:09 PM
    lol, nothing wrong with that anyway. Just means you get to see a broader spectrum of cool projects

    Doctor Popular joined...

    Read more »

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