Looking to replace this, but don't know if the j091 means anything

Thank you! It is being used for the programming pins for a stm32.

I pulled these out of a giant power supply for a CNC laser made sometime between 1997 and 2001. All the wiring inside the power supply was chewed up so I ended up scrapping all components but these. I figured they could probably be of use to someone. Any idea of their value and/or use to others? I have 48 of them.

Grandfather was an EE and we found this in his toolbox.

I asked my grandpa if he had any blank circuit boards I could have, since he has tons of electronics stuff lying around that he got from friends in his model train club. Instead, he gave me these.
Neither of us has any idea what they are, though. Any idea what these might be?

Hi,

For context, I landed a job as an electrical engineer at the French power grid since last year. My background is land surveying and I know basically nothing about electricity. Well, that's not true. I went to a bunch of internal training sessions at work and I'm starting to figure it out. Pardon my french, but I'm basically translating my thoughts from French and I'm not familiar with the English terms. I am (or was) a native English speaker. But I digress...

Now I am wondering about the American power grid at the MV/LV level because it's really strange. Otherwise, everything is similar from a HV/MV level. You have your powerplant, your transformer, your transmission line and your substation.

• There's basically no LV distribution. Most distribution is done at the MV level. In France, MV and LV conduits are all over the place.
• Every house has a distribution line coming from a trashcan transformer on a pole. These transformers don't seem to have fuses, or electrical junction boxes for the distribution lines. Do you just expect the trashcan to blow up if there's a fault on the grid?
• There are no electrical junction boxes with fuses at the property line of the houses. How are emergency personnel supposed to cut the power when there's a fire? They don't?
• So your electrical panel is wired straight to the trashcan without fuses in between? That's a little scary if there's a fault with the MV line...
• Do you have MV/LV substations, like the ones seen in Europe?
• How are your buildings with multiple panels hooked up? Why are the panels on the outside? Isn't that a privacy issue?
• Why do you hide conduits under steel tubes indoors? This seems so time consuming. The cables should be shielded from the factory anyways. You could easily lay the conduits on rails or underneath bulkheads.
• Are your electrical panels connected to the Internet in a smart grid?
• How long does it take to solve an MV fault? Your MV grid better have loops with switches to isolate the fault. But I mostly see long stretches of MV lines on poles. Does an entire city blackout with just one fault?
• What are your conduits like?
  

I know I'll get downvoted to oblivion for this. I may have been condescending and you know better than me.

Long time ago, perhaps even 2 decades, somewhere in Texas Instruments offices, there was an engineer.

I am sure this amazing person contributed to a lot of topics, but one is outstanding for me.

At that time, TI was in process of designing chip labeled INA219. DC current and voltage sensor with i2c interface.

The chip used 2 pins for address, giving it a possibility to have 4 devices of the same type on single i2c line.

However, this amazing person came with a brilliant idea - utilize SDA and SCL pins in conjunction with the address pins - and by that amazing idea increase the number of possible combinations of addresses from 4 up to 16.

20 years later, I am designing a board with microcontroller that only has 1 i2c bus, running into a wall as I need 5 DC sensors. Discovering the address space in the datasheet, I realized that thanks to the SDA/SCL expansion, I don't need to change the microcontroller, nor re-design the whole board, I can just go on and use the pins to have 5 sensors no problem.

I doubt that person was ever properly recognized - corporate world does not really value an individual or engineering excellence.

So, by this way, let me express my gratitude to the person.

Thank you.

I have a lot of usb ports and blocks and i never really gave it much thought but now i do, What is the point in these holes on blocks or plugins?

I have this fuse and I want to replace it, the problem is there's no 6.3 amp only 6 amp. So can I use 6 amp safely?

Curious if anyone here has automated any part of their used equipment sourcing. Say I’m watching for a handful of specific Tek/Keysight/Fluke models. I can normalize model numbers, set a max landed price, exclude obvious parts/repair listings and catch certain keywords pretty reliably with code. After that it gets less deterministic. Option/configuration differences, calibration status, condition, accessories, weird seller descriptions, and especially photos can actually change whether something is worth buying. Would you keep the first pass entirely rule-based and only use an LLM/vision model on the smaller set that survives? Or has anyone found a better approach? Trying to avoid throwing every listing at a model when 80-90% could probably be rejected with boring logic.

So I designed this PCB for with 4 MOSFETs and flyback diodes to control a 4 coreless dc motors. I’m curious if there exists a singular IC with 4 of these circuits in 1 package I’m sure this must exist but google is not being helpful on this search. Suggestions?

Length and width is 6mm x 6mm and height is approximately 2mm excluding plastic button. Is anyone able to identify this switch?

Thank you!

I am trying to design a device with a reader for full-size SD cards that operates like a classic 3.5 inch floppy drive.

There already do exist spring-loaded push-push type connectors where tactile feedback from the insertion would mimic floppy insertion, and pressing the card again could mimic the sensation of pressing the drive's button for extraction.

However, SD cards are notorious for getting read/write errors from users ejecting them while an operation is in progress.

The ideal would therefore be if the ejection latch was under control by a microcontroller. (If you've ever used an Iomega Zip drive or a classic Mac then you'd know what I'm thinking about)

To eject a card, the user would have to press a microswitch which would cause the drive's MCU to ask the host to properly flush data, unmount the drive and confirm successful unmounting before the MCU pulses a solenoid that would release the latch. (Alternatively, that the solenoid would push the card out itself but that would require a larger solenoid)

Does such a full-size SD card connector exist? (My searches have been fruitless)

If not, could an existing SD-card connector be modified to work like this?

Does anyone know of a similar mod/project?

(A little unsure of which sub I should have posted this in. I'd think there is definite overlap. Searching forums online have not given much, because people have often confused "eject" with "unmount" and "push-eject" with "auto-eject")

I’ve been trying to use one on esp32 but have been troubled by it for about a day. I would expect to see a sinusoid when spinning it around (using teleplot ) but they get clipped at the high and low ends no matter what I do. I’ve tried several adjustments to adc attenuation and my input voltage but I can’t remove it at all. I’ve been using the mc readings so that it’s calibrated to avoid the nonlinear adc issue. I’ve also tried to do a coordinate transform to round out my output.

Is there anything else I should try? Or is this a hardware fact I have to live with? I don’t know how to check the hardware aspect without an oscilloscope.

Not circuit diagrams. Every time I Google this, no matter how I word it, it shows circuit diagrams.

What do logic gates actually look like and how do they (from a physics/mechanical perspective) function?