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

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 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?

i want to make an ereader that also plays music. the ereader part should be pretty easy (a pico 2w or esp32 hooked up to an eink and an sd card), but for the music side of things, i am way less experienced, so i looked for easier to implement solutions. i found mp3 player modules that hook up to the MCU(like dfplayer mini for example) and also have an sd card slot built in, so i really just need to hook up the mcu to the module and be on my way.

however, i wouldnt want to have 2 separate sd card slots for books and music, so could i use the sd card slot on the module itself for both?

also is there a way to get the module to transmit the music back to the mcu, so i could play it over bt?

I’m trying to get the three front ultrasonic sensors working on my Lymow One Plus, using the original STM32 board’s power and interface circuitry as intended. I’d like to figure out the factory supply path before adding an external supply or changing any GPIO outputs.
I’ve attached full-board photos and close-ups. The coating makes the small component markings difficult to read. Does anyone recognize the three matching six-pin devices or the two three-pin parts beside them? More importantly, can anyone help work out where the front sensor supply comes from and what enables it?
Here’s what we have so far.
Hardware and measurements
Main MCU is an STM32F407V-series, 100-pin package. The second MCU is an AT32F403ARCT7.
Both chips’ flash has been backed up over SWD, with two matching reads of each. No firmware changes or GPIO writes have been made.
There are three front sensors: left, center and right. Each has red, black and yellow wiring. The modules are marked C26A03 / 0255E, but I haven’t found a matching module datasheet.
Their connections have been traced to the unpopulated 2×14 header footprint. My photo labels RR/RY, CR/CY and LR/LY mean right red/yellow, center red/yellow and left red/yellow; G marks confirmed grounds.
The three red-wire pads have continuity to each other. All measured 0 V with the mower running. The shared red net measured approximately 20 kΩ to confirmed ground with power disconnected.
A separate harness point labelled ULT_PWR measured 5 V, but there’s no measured continuity between that point and the front red-wire net. I’m not assuming they’re the same supply.
On earlier isolated bench tests, yellow idled around 2.6 V with 3.3 V supplied, and 4.2 V with about 4.9 V supplied. No convincing sensor reply was captured. That doesn’t establish the module’s rated voltage or prove the sensors are bad.
What the firmware shows
The STM32 contains a three-channel pulse interface whose timing is a very strong match for the Elmos E524-family IO protocol:
150 µs bits, with 100/50 µs or 50/100 µs phases.
A 250 µs command-mode interval.
Measurement windows of 8.25–46.25 ms, followed by additional captured edges consistent with a status reply.
Separate transmit and receive MCU pins: PA5 → PB1, PA1 → PB0, PA2 → PA7. The receive side uses TIM3 channels 4, 3 and 2.
Those are firmware pin pairs; their exact correspondence to the three physical yellow-wire connections still needs confirmation.
The Elmos E524.33 document specifies a 6–18 V operating supply, typically 12 V. That’s a useful lead, not a confirmed voltage rating for these exact modules. I haven’t applied 9 or 12 V based on that assumption. If you’re reading this you’re cool.
We also took read-only snapshots while the mower was running, roughly 19–46 seconds after boot:
TIM3 was configured for capture but stopped: CR1 = 0, DIER = 0, CCER = 0.
All three capture-event counters were zero.
The pulse driver’s state and descriptor records were all zero.
The three front-distance cache values stayed zero.
The rear ultrasonic readings changed normally during the same checks.
The firmware retains names ULT_F_1_task, ULT_F_5_task and ULT_F_10_task, but we haven’t found those tasks being created or a routine updating the front-distance cache at 0x2000130C. That strongly suggests dormant front acquisition in this build. It doesn’t prove nothing could enable it later in another operating state.
Possible supply controls
STM32 PD3 goes high during sensor initialization and was high in the live snapshots. It’s associated with the working rear-sensor code, but its physical supply net hasn’t been traced.
PE1 and PE8 are configured as outputs and have identified low-setting paths at startup/shutdown, without a discovered high-setting path. They’re candidates for an unused enable, not confirmed front-power controls. Other less certain candidates are PB8, PE4, PE5, PE6 and PE12. I haven’t toggled any of them.
Parts we’ve looked at
The eight-pin chip beside R250 is marked 8870 / TI…, matching a TI DRV8870 motor driver. The earlier idea that it was a sensor-supply regulator was a guess and should be discarded. Neither end of R250 showed continuity to the front red net in our checks.
Another eight-pin device appears to have a 4407-family marking, possibly an AO4407 P-channel MOSFET. That identification is tentative. The nearby two-pad footprint also showed no continuity to the front red net.
There are three matching six-pin circuits beside the sensor header, each surrounded by similar resistors/capacitors. They look like interface stages, but we haven’t identified the parts.
The two three-pin components beside those circuits are still unidentified. We also initially mistook a piece of grass for a jumper wire—there is no confirmed factory rework wire there.
I have a meter, logic analyzer, a Waveshare adapter that successfully accesses both chips over SWD, and the saved firmware/disassembly.
What I’m hoping someone can help identify is the original switched supply for the three front sensors: which component feeds the common red net, what voltage it should provide, and which MCU pin—if any—controls it. A schematic fragment, recognizable part marking, or a specific trace to check would be a huge help. I’d rather establish that circuit than keep guessing at nearby components or blindly switching GPIOs.

R-Right
L-Left
C-Center

I tried making it easy for myself.

I posted this a few moment ago and I was pointed out that signal jamming is illegal, not audio jamming.

So, I have been assigned a project by my college to create an audio jammer. As per what I know, I have to build something which targets audio signals and generate the opposite to destruct/Jam the audio. But, I don't how much of it is possible to implement, and how to do it?

I want to know what will be the best method and components required to make this work.

Also, if you have a better idea for implementation of the jammer, please let me know.

anyone recognise this chip it has isolator written above it can’t quite make out the numbers

The image shows the output of a TPS62933 buck converter under a constant load of 3A. (12V in , 5V out). The switching frequency is set to 500 kHz. Every time the buck switches (e.g. every 2us) I get voltage spikes of around 300mV, which seems quite high imo. I followed the spesifications on input and output capacitance and inductance. Is this just a result of bad layout, or are these measuring artifacts, or is this just normal behaviour for a buck converter ? Or is it something else ? Any input on why these spikes might happen would be much appreciated!

So, I have been assigned a project by my college to create an signal jammer. As per what I know, I have to build something which targets specific frequency and generate the opposite to destruct/Jam the signal. The title is very vague, so that's what I could thought of.

Its just a college project, so all I think would be good for practical is to "Turn On FM Radio and target the jammer for that specific frequency and make the radio stop."

I want to know what will be the best method and components required to make this work.

Also, if you have a better idea for implementation of the jammer, please let me know.

Hello, I am a hobbiest electronics engineer, and I have around 200 boards that I must program an EEPROM/NFC chip for, The chip uses the SO8N footprint, but theres around a million different probes that have different layouts and I am very confused. The chip I am using is the ST25DV04K. I have attached screenshots of the datasheet with relevant information. Can someone help me find the correct probe for this chip?

Thanks in advance!

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.

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.

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

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

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 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!

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!

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 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?

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+

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

Dear community, I'm working on a ESP32-S3 Wroom N16R8-1U custom project. Goal: Build an audio recording custom device based on ESP32-S3 (plus TDK T5838 microphone). ESP-32S3 should sleep as much as possible and get the wake-up signal from the T5838 and record the sound on a microSD card (max file size: 100-150MB). ESP should wake-up the wifi at a specific time, send the audio file(s) and put the wifi on OFF and continue to listen and record any voice activity. Device would work on a 3.7V battery therefore the power consumption should be very low. Device should be able to go into deep sleep to save the battery as much as possible and only allow the microphone to listen based on AAD D2 or AAD D1 depending on the preference. I have the schema of interconnected components in KiCad. Would be appreciated if a electronic design engineer working with ESP32-S3 can review the schema and advice if any electronic component should be added or is missing or the interconnection between already designed components should be re-arranged to avoid parasite currents or unnecessary discharge of battery. Any advice on saving the battery using optimal combination of electronic components is welcome.

If anyone has the willing to help me with that I can share the details of the existing already _SCH and _PCB.

If you read this line I really appreciate your effort and time reading this post.

Regards,