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Hack Chat Transcript, Part 2

A event log for Signal Conditioning Hack Chat

Massage those signals

dan-maloneyDan Maloney 02/17/2021 at 21:080 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:


https://www.homedepot.com/p/BECKETT-Electronic-Oil-Igniter-51771U/202312891

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
Hahaha

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
Yikes.

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
PRO TIP

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 into a propane flame, then speaker coils around it.

Jon Foote12:59 PM
Very neat project for Burning Man, but he took it there and the wind never died down.

morgan12:59 PM
bah

Jon Foote1:00 PM
I probably missed some questions as I'm a slow typer

morgan1:00 PM
I asked earlier... whats your favorite/oddest sensor at the moment?

Jon Foote1:00 PM
Great question!

Jon Foote1:01 PM
Haveing a lot of fun with a CO2 sensor

Jon Foote1:01 PM
if you put it on your desk it senses the co2 from your breath

Jon Foote1:01 PM
what if HVAC was driven not only by temp but by CO2?

Jon Foote1:01 PM
You know those impossible meetings in the closed meeting rooms?

morgan1:01 PM
huh, neat. I've been having fun watching just temp/humidity on my desk. I'm a heater!

Jon Foote1:02 PM
I think a lot of those are hard because your brain gets deoxygenated!

morgan1:02 PM
a damp heater even

morgan1:02 PM
yeah, I seen that research popping up more and more over the last couple of years

Jon Foote1:02 PM
Also PM sensors are fun. Turns out cooking is just as gnarly as a wildfire

morgan1:03 PM
I left tech and move into a wood shop, so a whole new set of bad air problems

I wonder if we're ever going back to those stuffy meetings again. For so many reasons.

morgan1:03 PM
Got a box of those PM sensors too, I want to get them installed around my house

Jon Foote1:03 PM
Yes, good point

Johnathan Carlson1:03 PM
re: 10kv shock: I was actually burning the bottom of my long board when it happened. The convex shape kept shedding water, hence needing to add more. Though, about a year later it paid off when a not so smart Graduate TA in the electronics lab was telling us to measure impedance with an ohmmeter while the circuit was live. I told him to stop being a dunce, he told me I'm just an (at the time) freshie that can't possibly know better, so I turned grabed my board that was next to me, flipped it over for him to see, then flicked the 12AX7 I wear as a necklace. He then listened to my explanation and took me seriously. I probably saved some pour soul from having to replace two dozen fuses in high end multi meters that day.

Kevin Andersen1:03 PM
Adafruit also has a great CO2+TVOC (votatile organic components) sensor that I recently used to prove to my landlord that my ventilation brought in exhaust fumes from other apartments https://learn.adafruit.com/adafruit-sgp30-gas-tvoc-eco2-mox-sensor/ I had fun and I got my ventilation fixed!

morgan1:03 PM
in particular before fire season and to compare against winter condistions where everyone is burnign wood

morgan1:03 PM
out house included

morgan1:03 PM
our

But, we're past the end of our hour, so we need to wrap up. As always, the Hack Chat is always available, but we do have to let Jon get back to work if he needs to. I just want to say a big thanks for coming on today and chatting with us like this. And thanks to everyone for coming in with great questions.

kalspelletich1:04 PM
I am coercing comrade Foote into this exciting project: https://kaltek.wordpress.com/2021/01/29/measuring-the-cosmos-global-human-positioning-night-sky-laboratory/

Jon Foote1:04 PM
Sweet!

Jon Foote1:04 PM
Thanks all!

Kevin Andersen1:04 PM
thanks Jon for your time, and everyone who shared resources and tips!

Johnathan Carlson1:04 PM
@Kevin Andersen - Adafruit recently got a CO2 NDIR sensor too, so true CO2

Dusan Petrovic1:04 PM
Thanks @Jon Foote !

Dave Blundell1:04 PM
thanks

morgan1:04 PM
thanks Jon, good 'seeing' you (I miss Benders)

Jon Foote1:05 PM
I will try to summarize resources. I should probably do that in a hackaday.io project :)

Johnathan Carlson1:05 PM
Thank Jon!

Kevin Andersen1:05 PM
@Johnathan Carlson ooooo, interesting!

Jon Foote1:05 PM
Nice to "see" so many pals here! thanks for coming!

doctek1:05 PM
Thanks!

Thanks Jon! And next week we'll be talking DIY Neuroscience with Tim Marzullo - event page to come...

Jon Foote1:10 PM
Thanks Dan! Kalman stuff

Jon Foote1:10 PM

https://www.bzarg.com/p/how-a-kalman-filter-works-in-pictures/

Bzarg tbabb

How a Kalman filter works, in pictures

I have to tell you about the Kalman filter, because what it does is pretty damn amazing. Surprisingly few software engineers and scientists seem to know about it, and that makes me sad because it is such a general and powerful tool for combining information in the presence of uncertainty.

Read this on Bzarg

morgan1:10 PM
cool, something I still don't quite grok

Jon Foote1:10 PM
Also this is good

Jon Foote1:10 PM

https://medium.com/@jaems33/understanding-kalman-filters-with-python-2310e87b8f48

Medium James Teow

Understanding Kalman Filters with Python

Today, I finished a chapter from Udacity's Artificial Intelligence for Robotics. One of the topics covered was the Kalman Filter, an algorithm used to produce estimates that tend to be more accurate than those based on a single measurement alone.

Read this on Medium

Cool, I'll add those to the transcript. Thanks!

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