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#electronics

53 posts49 participants3 posts today
Public *
niconiconi

Wrote more #openEMS documentation. The math notes on the old project wiki need cleanup. The equations were written in absolute permittivity and angular frequency, while the software expects you to enter a relative permittivity and ordinary frequency, making it a cross-reference headache. ​:woozy_baa:​ I'm pretty sure the Debye formula is now correct, but I still need to check the Lorentz model. #electronics

Math Notes ================== Debye Model """""""""""" The Debye model is defined by the following formula. .. math:: \begin{align} \epsilon_r(f) &= \epsilon_r(\infty) + \sum^N_{p=1}{\frac{\Delta \epsilon_{r,p}}{1+ j (2 \pi f) t_\mathrm{relax}(p)}} - j \frac{\kappa}{2 \pi f} \\ \end{align} where: * :math:`f` is the frequency. * :math:`\epsilon_r(f)` is the material's relative permittivity. * :math:`\epsilon_r(\infty)` is the material's relative permittivity at :math:`f \to \infty`. * :math:`\kappa` is the material's electric conductivity. * Note that electric conductivity :math:`\kappa` is not to be confused with material permittivity, which is sometimes also denoted by :math:`\kappa` in the literature. * :math:`p` is the index of the model term currently being evaluated, with up to :math:`N` number of terms in total. * :math:`\Delta \epsilon_{r,p}` is the p-th oscillator strength. * :math:`t_\mathrm{relax}(p)` is the p-th relaxation time.
Public
C.

Schematic: "2022 - We've updated the circuit design to use widely-available part AB1234DL rather than the impossible-to-find one the original design used!"

<search Newark/RS/Element14>

Website 2025: "AB1234DL: obsolete, not available to order"

Sigh.

#electronics#hobby#obsolete
Public
Ari [APz] Sovijärvi

I don't know why, but there's certain beauty to the 80s electronics. This here is a Williams WPC platform pinball backbox board set (this sub-model, WPC Security, is from around '94, but the set was originally designed in late 80s and used until mid-90s when they got a face-lift combining several boards).

In this picture lower left corner is the CPU board that houses a 6809, its RAM, ROM, NVRAM batteries and its namesake WPC ASIC chip that replaces a bunch of PIAs older platforms used.

Right above it is the Fliptronic board that controls the flipper coils and deals with optical flipper buttons.

In the top middle is the DCS sound card, that plays all-sampled sound tracks and all the sampled speech and effects.

Going right the next big board is the DMD controller, which in this platform does not have its own CPU, but is instead spoon fed by the main CPU.

The biggest board on lower right corner is the driver board that drives all the coils and lights.

View of an open pinball machine backbox, with multiple huge printed circuit boards, full of components and wires criss-crossing all over. Some red LEDs can be seen in most boards.
#pinball#arcade#electronics
Public
DoomsdaysCW

#UK - The Restart Project! Lots of locations, lots of dates!

"The Restart Project aims to tackle the climate emergency by making #electronics work for people, for the planet, and for longer.

"We’re a people-powered social enterprise that believes every product should be repairable, and that repair and reuse should be accessible and affordable for everyone.

"Right now, we live in a throwaway economy. It can be tough to find options for repair locally, and electronics can be needlessly hard to fix. As a result we’re losing repair skills in our communities, throwing more away, and buying more new. It’s building a mountain of e-waste while using ever more of our planet’s limited resources.

"That’s why we make repair easier for everyone.

We help people run repair events in their communities where they teach each other how to fix their broken and slow devices – from tablets to toasters, from iPhones to headphones. We run fixing factories that help people repair their things, build repair directories where people can find help near them and train people in repair skills."

therestartproject.org/networks

#RepairCafes #RightToRepair #BuildingCommunity #ReduceReuseRepair #ReuseRepair
#RepairCafésUK #SolarPunkSunday

Public
Calishat

#trees #electronics #sustainability

'A waste gum produced by trees found in India could be the key to unlocking a new generation of better-performing, more eco-friendly supercapacitors, researchers say.

Scientists from universities in Scotland, South Korea and India are behind the development, which harnesses the unique properties of the otherwise useless tree gum to prevent supercapacitors from degrading over tens of thousands of charging cycles.'

gla.ac.uk/news/headline_117059

www.gla.ac.ukTree gum supercharges supercapacitor lifespan, research revealsA waste gum produced by trees found in India could be the key to unlocking a new generation of better-performing, more eco-friendly supercapacitors, researchers say.
Public
kopper

electronics fedi i need your help.

so i have these headphones that have been broken for years now and want to see if i can repair them. the issue as far as i've been able to tell is these solder joints (pictured) are broken and not properly connecting.

how hard would it be for someone who has never even breathed in the same room as a soldering iron to go about this? can i just buy the cheapest junk soldering iron and solder online and make it work? what do i need to know before attempting this?

(before you pledge allegiance to your favorite solder brand or send amazon US links my way let me clarify i am reasonably confident none of the brand names you recommend will either be available to buy over here or as cheap as you expect)

#electronics#repair
Public
Calishat

#electronics #hardware #EWaste

"Those well-meaning agitators at the Public Interest Research Group (PIRG) are back, this time with an interactive "Electronic Waste Graveyard" cataloging a range of devices tossed aside after software support expires or cloud connections flatline.... its latest effort is an online 'rogues' gallery' showcasing more than 100 tech products that no longer function properly or were effectively junked after manufacturers ended support."

theregister.com/2025/04/11/ele

The Register · PIRG's 'Electronic Waste Graveyard' lists 100+ gadgets dumped after support vanishedBy Dan Robinson
Public
Kevin P. Fleming

I could use some suggestions from electronics geeks.

I've got a need to control two active-low inputs to a buffer IC in an 'exclusive' fashion: only one of them can be low at any moment in time. I've already got pull-up and pull-down resistors to ensure that they start that way during powerup.

I'd been planning on just connecting them to a pair of GPIOs from the microcontroller, but I'm concerned that during reset, if the normally-low pin was being driven high, there will be a short time when both inputs will be low as the MCU outputs move to high-Z... I can't guarantee that the reset in the MCU will cause both pins to go to high-Z simultaneously.

Is there a straightforward circuit I can drive from a single GPIO to generate a low signal on one of two outputs in a 'break-before-make' style (to abuse an old relay term)?

The reason that I need to do this is that two of the buffer's outputs are connected to two of its inputs, so if both control inputs are low at once that will generate a circular connection and I have no idea how the buffer chip will behave.

#Electronics#CircuitDesign
Public
Sunflower Björnskalle 🌻

Wow, this was a surprisingly detailed article about how to fix a jumpy mouse scroll wheel by fixing or replacing the encoder.

Unfortunately, I do not feel up for this right now actually. It's cool to know it's possible though.

makeuseof.com/fix-mouse-scroll

MUO · How to Fix a Mouse Scroll Wheel Jumping Up and DownMouse scroll wheel jumping up and down and making control difficult? Here's how to fix it.
#electronics#consumerelectronics#electronicsrepair
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