@bornach@fosstodon.org
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bornach

@bornach@fosstodon.org

I like hackspace stuff, STEM education, discrete electronics, microcontrollers, Raspberry Pi, kinetic art, electronic music synthesis

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Workshopshed, to random
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Robots everywhere #MakersCentral

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bornach,
@bornach@fosstodon.org avatar

@Workshopshed
YouTube makers all in one corner
#makerscentral #KidsInventStuff

rodhilton, to random
@rodhilton@mastodon.social avatar

All this AI shit Google is rolling out might legitimately make me switch to iPhone.

Like the entire presentation was some kind of hellscape, I don't want any part of this weird shit.

bornach,
@bornach@fosstodon.org avatar

@golgaloth @rodhilton
Or just stick a Sim in that old feature phone you still have in a drawer somewhere

jonty, to random
@jonty@chaos.social avatar

I enjoy talking to spammers

bornach,
@bornach@fosstodon.org avatar

@gsuberland @jonty
They changed their name to Londonland Paris like decades ago

gsuberland, to random
@gsuberland@chaos.social avatar

what if radioactive materials are really just sentient beings using echolocation / time-domain reflectometry to learn about their surroundings?

bornach,
@bornach@fosstodon.org avatar

@gsuberland
Could they be mating calls? Explains the sudden increase in radioactivity when you bring two subcritical masses within range of each other.

bornach, to Electronics
@bornach@fosstodon.org avatar

Testing the switching characteristics of cheapo PC817 optocouplers from Ebay.
555 timer astable is generating a 37kHz square wave test input.
Rise/fall time is way out of spec for use in #MIDI. But the recommended component, 6N138, is much more expensive.

Instead have the #optocoupler drive the base of an NPN #transistor and by adding appropriate resistors, I get much improved switching speeds. Is this good enough for a MIDI input circuit? #electronics #oscilloscope #breadboard

Oscilloscope shows the 555 timer output as a yellow square wave, and the optocoupler collector-emitter voltage as a blue waveform that is anything but square. At 37kHz the output signal is clearly not usable
The oscilloscope is now hooked up the the collector of the NPN transistor whose base is driven by the 2nd optocoupler. The blue waveform is a near perfect square wave, with rise/fall times well within 2us spec for a MIDI application.

bornach,
@bornach@fosstodon.org avatar

@mike805
[IMSAI Guy] explains the cascode amplifier trick
https://youtu.be/APUhm2tsCiE

See Figure 13 High bandwidth optocoupler configuration
https://www.onsemi.com/pub/Collateral/AND8273-D.PDF

I might need to try that for comparison

bornach,
@bornach@fosstodon.org avatar

@mike805
I tried the #cascode #amplifier trick with the PC817 #optocoupler. IMSAI Guy only showed how the voltage of the transistor base affects the speed of the falling edge. But notice how the rising edge remains largely unaffected.

By comparison, the common mode NPN #transistor amplifier with 150 ohm resistor across base-emitter, yielded noticeably sharper rising/falling edges
#electronics #oscilloscope

Optocoupler and NPN transistor in cascode amplifier configuration. A potentiometer adjusts the base voltage of the transistor. The oscilloscope displays the cathode input voltage as a yellow square wave. The blue waveform is the voltage of the transistor collector - it exhibits slow rise and fall times that are perhaps caused by the Miller effect. Adjusting the potentiometer visibly improves the sharpness of the falling edge but has much less of an effect on the rising edge.

bornach,
@bornach@fosstodon.org avatar

Possible explanation for why you tend not to see optocoupler chip packages that combine a phototransistor/photodiode in a cascode configuration with a regular transistor in one integrated circuit, see this answer in Electronics (27 April 1978, page 154)
https://worldradiohistory.com/Archive-Electronics/70s/78/Electronics-1978-04-27.pdf

By contrast, optoisolator ICs such as the 6N138, arrange for the phototransistor emitter or photodiode anode to drive the base of an NPN BJT

diyelectromusic, to random
@diyelectromusic@mastodon.social avatar

Here is a "to-do list" of some interesting Arduino audio and MIDI frameworks that it might be interesting to take a look at, at some point.

Do let me know if you've used any of them or have others to suggest!

https://diyelectromusic.wordpress.com/2023/04/29/arduino-audio-and-midi-frameworks/

#Arduino #MIDI #Audio #Synthdiy

bornach,
@bornach@fosstodon.org avatar

@diyelectromusic
Not exactly an Arduino framework, but I've recently played around with Vult DSP which can generate MIDI/synth code for Teensy and Pico ADK

https://github.com/vult-dsp/vult

atomicpoet, to random

I'm hoping @futurebird can settle an age old debate.

A Bug's Life vs. Antz

Which movie is better?

bornach,
@bornach@fosstodon.org avatar

@atomicpoet @futurebird @bok_bok_ba_gok
There's precedent for movies told from the point of view of the lowest caste in society

https://en.m.wikipedia.org/wiki/The_Hidden_Fortress

But that would probably only work in Japanese cinema. No big Hollywood Disney-owned blockbuster franchise would ever attempt such a thing

bornach, to music
@bornach@fosstodon.org avatar

Moritz Klein and SimonTheMagpie live streaming now - reverse engineering the TR-808 cowbell

https://www.youtube.com/live/1ZJ8BzrOsZM?feature=share
#electronics #Music #synth #tr808

andypiper, to random
@andypiper@macaw.social avatar

Turns out that if you receive an emergency alert while driving, there’s a noise, a huge banner appears on CarPlay that does nothing when tapped (had an arrow implying more), and then it goes away. Oh, and my watch buzzed as well, I guess.

bornach,
@bornach@fosstodon.org avatar

@andypiper There was also barely audible voice message after the noise. Did anyone hear it?

bornach, (edited )
@bornach@fosstodon.org avatar

@proactiveservices
I found the setting

Not all phones were speaking the emergency message
https://youtube.com/shorts/enKmrWQeHzM?feature=share
That sounds like a pre-recorded message and not the phone using text-to-speech

blakespot, to art

XboxAhoy's recreation of Jack Haeger's lovely "Four-Byte Burger," referenced in my earlier toot, displayed in phosphor glory on my Amiga 1000 and its 1080 CRT. (XboxAhoy linked the IFF in the post to his sub - r/XboxAhoy - on reddit).

Obviously that old 1080 doesn't like to lie on its side! Eek!

So very lovely!

#Amiga #vintagecomputing #retrocomputing #computinghistory #pixelart #pixels #graphics #JackHaeger #computerart #1985 #techhistory #pixels #art #restoration #Commodore #vintatgecomputers #reddit

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bornach,
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@blakespot @paulrickards @48kRAM
It's plausible although that magnetic field is very weak
https://youtu.be/YZqyNyOyJmU

Could also be caused by magnets found in nearby loud speaker. Discovered this by placing large stereo speakers too close to a television in early 2000s.

If there is no degauss, according to this Reddit comment
https://www.reddit.com/r/retrogaming/comments/90h5y3/turned_my_crt_sideways_to_play_phozon_got_a_cool/
"just let it rest without power 10-15 minutes both before and after turning it"

bornach, to random
@bornach@fosstodon.org avatar

Oh no! Free batteries appearing in the wild in Canada too!
https://youtu.be/lidMQu3S2NU
Haven't seen either of those in the UK not even under a different brand name. [pileofstuff] measured 4V on the battery from the rechargeable , 3.3V on the non-rechargeable

bornach,
@bornach@fosstodon.org avatar

Look at how small the battery is in relation to the size of the disposable
1.48Wh (400mAh 3.7V)

Might be useful should I need to replace another battery in some wireless device, assuming I can recharge it - voltage is reading very low 1.2V

bornach,
@bornach@fosstodon.org avatar

Hooked up the tiny lithium polymer battery to a TP4056 PCB to attempt recharge. Note the RProg resister has been replaced to limit current to 230mA. The terminals are so close together I've put masking tape over the positive terminal and clip to prevent accidental short

bornach,
@bornach@fosstodon.org avatar

That pressure sensing capsule found in most disposable pens can very easily be turned into a switch that is capable of switching currents high enough to activate small relays and solenoids

Simply slice the top off, exposing the edges of the inner and outer conductive cylindrical walls. Bridging the two walls with something no more conductive than human skin is sufficient to trigger it

Pressure sensing capsule found in most vape devices shown with top sliced off revealing a 5 pin chip. It has been hooked up to a cylindrical lithium polymer battery (which was also salvaged from a discarded vape pen) via crocodile clips. The chip is also connected to a small solenoid which is activated whenever the exposed sliced edges of the sensor capsule are touched by my finger. A blue LED underneath the capsule lights on each touch.

bornach,
@bornach@fosstodon.org avatar

Touching only the inner wall with a wire seems to trigger it also. Implies that it is actually a capacitive touch sensor

bornach,
@bornach@fosstodon.org avatar

14 months worth of salvaged vape pressure sensors - enough to make a capacitive touch keyboard?

stux, to animals
@stux@mstdn.social avatar

A puuuurfect shadow

#cats #BigCats

A leopard and black leopard walking together almost in sync, woahh

bornach,
@bornach@fosstodon.org avatar

@stux
https://youtu.be/e90NJIO-qyo

bornach, to random
@bornach@fosstodon.org avatar

How did I not realise that DAB+ had all but obsoleted DAB?!
I wondered why my old pre-DAB+ radio seemed to receive fewer and fewer stations with each passing year. I started relying more on streaming radio via Google Assistant but even that seems to be getting less reliable with recent tech layoffs and the pivot to chatbot AI.
https://www.nytimes.com/2023/03/15/technology/siri-alexa-google-assistant-artificial-intelligence.html

Maybe I should turn my non-DAB+ radio into an Internet streaming device
#DAB #DABplus #DigitalRadio

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