I ordered some DDR4 green pcb DIMMs from Ebay and they came wrapped in aluminum foil. This seems weird. Is it?

I've noticed there are a lot of low cost (~$20) GPS tracking devices on Amazon, that have no monthly fee.

Does anyone know how they are able communicate their location back to the tracking device (phone)? I assume they must be using some cellular service, but there is no monthly fee. Is there some way they are able to send small amounts of data over cell networks for free?

It can't be Bluetooth, Wifi or UWB because the range is too short.

Apple Airtags use Bluetooth/UWB when the device is close by, but when it's out of range they connect to other random Apple devices in the area to send data.

But these aren't Apple devices, so how are they doing it?

Here are a couple of examples:

https://www.amazon.com/Real-Time-Location-Compatible-Wristband-Waterproof/dp/B0HJQLMWWS

https://www.amazon.com/Real-Time-Location-Wearable-Wristband-Waterproof/dp/B0HHJ2SYJF

I opened up an old laptop hoping I could fix it. On the plastic I saw this corrosion like spots. Any idea what it could be?

Idk whats next here with my school project, had claude help me but after putting the supply the relay isnt clicking, my supply is 9v battery but it says on the schematic source is 9-12v supply and the also the relay is 12v... so im thinking maybe the supply inst reaching the relay but my prof provided a supply for but somehow still didnt work

I live in an especially humid country and I recently bought an electronics component organizer (The 30 compartment Stanley organizer to be precise).

I previously used to keep my electronic components in a tightly sealed plastic box but the pins of most components eventually rusted due to high humidity.

This new component organizer is not sealed like my previous storage solution and I'm also planning to put 1 silica gel sachet in each compartment to help with the humidity.

Also, is it alright to not keep the mosfets, esp modules and other chips directly in the organizer without anti-static coverings?

Or should I use anti-static bags?

It works but when you switch it off it either 1) stays on, 2) turns off, or 3) turns off and back on a few minutes later. Is this something that's somewhat easily fixable? Buying a new one will cost $100+

I am an electronics student and I have been struggling with this assignment for a few days. I need to design a stiff VDB PNP transistor circuit. The only variables I have so far are Vcc=5 V, Ic=20 mA, and hfe of 200 is assumed. I am using numbers for a red LED so far, so 1.8 V across it. I am getting stuck at figuring out how to calculate R1and R2. I don't necessarily want the answers straight up, but some guidance on where to start would be very helpful.

My low-side N-MOSFET turns on unintentionally when a 32V supply is applied to the drain. The gate has a series gate resistor, an external Miller capacitor (gate to drain), a Cgs capacitor and a gate-source pull-down resistor. I see a spike on the gate of the MOSFET, which turns on the transistor just enough to see a current spike through the drain.
I suspect dv/dt-induced turn-on through the Miller capacitance.
What should I check or change?

A while ago I bought a fluke ti32 wide1 lense but the seller did not include an SD card with required firmware to update the unit so it has the ability to do a wide fusion view.

Would someone here be able to provide me a digital copy of the contents of their sd card?

Here are original FLK-LENS/WIDE1 instructions:
https://media.fluke.com/b568f40d-2b11-41d3-8586-b10800c01515_original%20file.pdf

I contacted fluke customer support but they were unable to assist me:

Unfortunately, we no longer can supply the codes for your FLK-LENS/WIDE1. We no longer have the ablility.
...
I understand why you're asking. I have been with Fluke for over 25 years now. Not sure if that counts as an “old engineer”. That said I can tell you that the asset that was used to produce the information is no longer available to me or my team.

Does anyone have a fluke ti32 or know someone who does that also has either a tele1 or wide1 lense with firmware sd card?

Even if it was for the wrong model (TELE1) I could see the contents and format of the data is expected and try to reverse engineer it.

I tried ebay sellers and they all told me to kick rocks or sucker up and buy theirs (note most sellers don't even have it either or don't know it is required).

I am willing to pay a reward too.

I know that germanium transistors have fuzz because heat messes with their conductivity and I thought “well couldn’t a diode do the same thing?” And I know one won’t work but if I chain a bunch of them together like those old barretter radio detectors would I be able to get noticeable fuzz?

I try to use this circuit to control a beacon. I know this isn't perfect by any means, I have no voltage regulator and I could further limit the current that flows through some components. However, my problem is the following:
The astable multivibrator on the left should activate / deactivate the BC557 to create short "beeps" via PLSE. However, the voltage on PLSE is never dropping below 7 V (measured with a multimeter), which means I won't get a single tone out of my beacon. I guess this is related to the size of the resistors, but I'm not sure what to do to fix the circuit. Any help would be much appreciated!

Dell inspiron way too old lol

So, my battery is dead.... i use to notebook for work, only and i need to keep it plugged to the charger......

But this damn thing keeps turning off. Its a bad connection, im not sure where, exactly!

Heres some pictures, if you dudes could help me solving this T.T

Have an OPA1656 (2 channel) wired up as an inverting amp with unity gain, off a tle2426 rail splitter to the +IN at 12Vdc. (only one channel shown in the image)
The Signal to the -In is, Input to board-> 2.2Uf Cap ->10kΩ resistor then branch to -In and also to another 10kΩ resistor (with a 22pF cap in parallel) to the output of the OpAmp. There is a 100nF cap from the V+ to Gnd. There is no oscillation.

Problem is, a 2Vpp 1khz signal before and after C10 is strong BUT there is only a 100-150Mv 1k signal on the output. Checked from pin 7 to gnd, and after C9 above...
The Audio input and OpAmp grounds share the same net, so nothing is floating.
Both the +In and -In are at the same voltage (hair less than 12) so the opamp IS managing that much. The other channel provides same exact nothing. none of the pins on the opamp or circuit that follows is shorted. R20 and R21 both measured to be 10k each. R22 and C10 both check out ok, no shorts....

I have been beating my self up for far too long. Does anyone have any ideas on why the opamp output is not giving me an inverted signal of the -In ???

I have a body control module for a vehicle, found out that it would not start because of the burned diode shown in the pictures. Vehicle has been repaired but I am wanting to fix and see if the whole motherboard has been compromised or just replacing the part would be the fix. Also I am having trouble finding the part or even figuring out what company this component is from. I just need something so I can buy it online. Thanks in advanced.

hi folks. i am trying to repair a mitutoyo solar digital caliper

it appears that it doesn't have a battery, but it has supercapacitor (since it's solar paneled)

i notice that when i take it out of strong, direct light, it instantly fails and turns off. i figure i need to replace the supercap, but I can't seem to find the specifications for (mitutoyo does not publish this).

you can see it on the pcb in the image i attached (orange)
i am wondering, what can i do to get the specs of this supercap? I don't see any markings on it unfortunately.

for those wondering, it's a mitutoyo 500-421. i believe it is from 1990

but it's a quality tool, as you may know

I'm trying to find a replacement for a right angle header connector that I got in a kit that I broke. I cannot figure out the mating vs. post length, and trying to do it by process of elimination on DigiKey is not helping. The picture is what they sent back when I asked, along with the description of "They are standard 90 degrees angled headers - both sides of the pins are of equal length." The pitch is 2.54mm. This is from a British group, if that makes a difference. Any help in identifying the contact and post length would be greatly appreciated.

Here is the link for the schematic circuit: https://www.falstad.com/s.php?s=QzJ7Ds

Instructions do not show the name of this component or how exactly to use to connect a power source

I have an Ion Pathfinder 1st gen speaker with a brand new 12v 7.2Ah battery I put in, since the speaker sat in storage for over a year without getting charged and the original battery died. The speaker runs great with the new battery, but it refuses to charge when the speaker is plugged into AC power. I’m able to charge the 12v with a smart charger and it’ll hold the charge and run great, so the battery isn’t the issue. The speaker also runs with the 12v removed and the speaker plugged into AC power, and it reads over 15v on the output side of the internal power supply PCB. However, with the 12v disconnected it’s reading .11v on the terminals that connect to the 12v. With the 12v connected and probing “B+” labeled on the main PCB, its reading the same voltage as the 12v. Anyone have any ideas? It’s impossible to find replacement parts for this speaker and it was pretty expensive when I first bought it, so it’d be great to get it working normal again and not have to disassemble the entire thing every time I need to charge it. Thanks!

These were in with a big batch of carbon film resistors I got. What are they? Thanks in advance!

Despite it not being easy at all, taking a 12v dc source from a battery, how could I modulate it to 50 hz to then send it to the secondary winding of a transformer?

I found this schematic between the pages of an old TI databook I bought from eBay. What do you think it does (if it actually is a complete diagram)?

The chips used in it are (I think) two 7473 dual J-K flip flops, one 7493 4-bit counter, one 74374 octal D latch, one 7447 BCD to 7-segment decoder, and a 555 timer.

I would just put it together on a breadboard to see if it does anything, but I don't have some of the ICs for it.