I am looking for advice, on a thought I had. I wanted to combine a fairly simple phone (preferably non gogole) with a tablet for my daily use. I am ok with the tablet running Android, as I more or less am required to have it (or apple), for safe log in, in my country

The idea is, to not spend all the time death scrolling on the phone, and only bring up the tablet up when I need to use features that are not available on the phone. What I still was hopping for, was a phone with basic functions, like calling, SMS, mail and calendar. Also it should have a good camera, and some sort of privacy orientated navigation app. It should also have hotspot, so that I can connect the tablet to the internet through it. I wouldn't mind an e-ink display, but I am not sure how that works with a camera or if they even do come with quality cameras.

Do you think that you get more value for the money with a tablet, than a phone? Should I spend the equivalent to a flagship phone on a tablet, or would i be getting more value, by simply buying a phone, and dropping my plan on having a semi-dumb phone?

Hi! I recently purchased a nice gadget from AliExpress, this should be the circuit to drive an ultrasonic piezo. Silly me, I put the batteries backwards and the U1 component on the bottom left blew up.

I know a bit about circuits so I reverse engineered it (there might be mistakes), but I am not skilled enough to identify the component in order to look for a replacement. Can someone help me identify it? I can read ___22 on it.

Here's another version of the schematic, which might be easier to understand.

Thank you for your help!

EDIT: I couldn't identify the component, but I did a Google Image Search as suggested by @partial_accumen@lemmy.world and it found similar PCB designs. It very much looks like this component is part of the charging circuit, which I do not particularly care about. I will try desoldering it and see if the rest of the device still works. I will post the outcome here.

EDIT 2: with a lot of help from @jeinzi@discuss.tchncs.de I managed to fully reverse engineer it and fix most of the mistakes in the schematic. That component was just an FP6291 after all, part of a circuit to step up the 3V from two AA batteries to 5V required by the MCU. I replaced that whole section with a step up module I had previously purchased from AliExpress, and now everything works again.

Here's the final (mostly accurate, hopefully) revision of the schematic.

(link)

Lessons learned:

• Always double-check battery polarity
• In the age of AI, Google Image Search can now help identity circuits
• Sometimes a circuit that looks complex can actually be much simpler in the end
• AskElectronics@discuss.tchncs.de amazing community on Lemmy

That was fun! Thank you very much to everyone who contributed to this thread!

I bought a cheap Hantek 6022BE to learn with and I'm just trying to measure some voltage to check if it's accurate. I'm using openhantek6022 https://github.com/OpenHantek/OpenHantek6022 and also hscope on android. I'm measuring a 19v laptop power supply with the 10x setting on the probe and also a set of leads with a 20x attenuator. When I measure the power supply with my dmm I'm getting 19.22V with the scope I'm getting much higher or lower depending on where I set the voltage per division. Both programs have a calibration function which I did.

20x attenuator showing 19.6v

10x probe showing 20v

10x probe with 2v per division setting only showing 9.81V

Hscope showing 19.9v

I recently got a Raspberry Pi Zero 2 W.

I'm hoping to set up a circuit (with attached solar panel and battery) to activate at regular intervals to preform a servo motor movement. I'm not sure how often I can make the activation, as I don't know the power draw of the board or movement, or how fast the solar panel will charge the battery. I hoping there is a way to measure the power draw of the board and attached circuit, along with the battery level, over an extended time frame and in an automated manner. Is this possible?

Thanks for your time.

Edit: Addional info:

• This would be likely a one off characterization.
• I would like time series data over several days or longer.

i am building a 3d printed Stargate with lights and sounds using a D1 mini and a DFPlayer mini. The code is from this github repo: (https://github.com/spradlinb/Stargate_3D). when i compile the code in the Arduino IDE i get a SPI error as depicted in the image. I've tried remapping the gpio pins with no success. what am i doing wrong? BTW here is a video of what i'm trying to build: https://youtu.be/y01J-hymaDs

Hey all. I'm looking into getting a small action cam type of camera. Primary purpose would be for travel and recording music playthrough videos at home. My wife would like something small and discreet that she can use to take short videos while traveling, but not make her look like an obnoxious vlogger. At the same time I'd like to use it in my home studio to make videos. Doesn't have to be 4k, 1080p would be fine if it doesn't meet the budget limit. I'm looking into something less than $200.

Anyone have suggestions?

I have a Logitech MX Anywhere 3 mouse. In the past, my main mouse buttons started getting unreliable. I ordered "gaming" high quality switches from AliExpress and had an electronics repair shop install them. They gave my mouse a new lease on life. Apparently they should last much longer than the original ones. So far, no issues.

But even back then, my middle click was starting to act a bit wonky. The technician cleaned out, but without parts, he couldn't do much else. It didn't help.

Now, a couple of years later, the middle click is getting really bad. Almost always either multi-clicks or doesn't click at all when pressed once.

My friend found what looks like an OEM Logitech replacement wheel. Here it is: https://www.aliexpress.com/item/1005008242236011.html

But if it's the same, is it going to start dying again in less than two years?

Is there something I can do (or rather have done; I don't have the dexterity for soldering) to actually improve its durability?

By the way, the magnetic sometimes ratcheted, sometimes smooth scroll wheel is kinda important to me. So I want that feature to stay.

One last question: it's been maybe 4 or 5 years, not sure how long exactly. Should I get the battery replaced at the same time, while I'm paying for shipping and installation? The charge has been holding less and less, but it's not the end of the world yet. But should I expect it to get exponentially worse soon or something?

trying to save an old motherboard, it's a Gigabyte GA-B75M-D2V. tried searching, got nothing usable back.

problem: no USB ports work - all the ones on the back, both USB 2.0 and 3.0, and all front ports. USB ports not working is common accross boards and manufacturers, but it's usually a subset, some work some don't and you can still use the thing.

ports have 5V, when the keyboard gets connected its leds light up for a second but don't stay on. the mouse's led doesn't light up when connected. neither are detected by the UEFI setup.

I got a PCI-Express USB 3.0 card, but that thing doesn't work for booting off of it or in UEFI setup, etc., only after boot from HDD.

otherwise, everything works - LAN, sound, audio, SATA, etc. I feel the platform still has a lot of life left, especially for my use cases.

this is not a software or settings issue, that's why I'm in "ask electronics" something is fried here and was looking for pointers what or where to look at.

no visible burns or busted caps and such. hoping it's something simple, any ideas what to look at?

7 Year old monitor started to have panel issues today, no initiating event. Did the normal trouble shooting, shut every component down, disconnected, swapped cables, updated firmware, changed resolutions, etc... issue persisted.

Took it apart to have a looksie

Getting all the plastic snaps off the back of the monitor was the single longest part of this... very annoying. I miss easy to repair devices.

The PSU has shorts!!

the other side of the pcb is a transformer

some other leaking seen as well

both sides of the PSU in full

the logic board looks fine

I'm tempted to just fix the shorted pads and test the voltages... I probably should replace the transformer

Lots of chatter on youtube about the thunderbolt ports dying on this monitor, but I don't think that is applicable to me. At least the PSU shouldn't look like this even if its not the core problem.

Any insights or suggestions from those you have rescued erstwhile monitors? This is the first monitor that has ever fully died on me. I melted a laptop screen sitting too close to a fire.. heh, but it was still usable.

I bought a 2nd-hand 12v 2A power supply without branding. I intend to use it on a DVD player. Coming from the street market makes it dicey because anything in that market could be from someone’s dumpster dive. To ensure it’s useable I used a DMM to measure the volts. It started at 18v but continued to gradually climb. When it passed the 20v scale on the DMM, it quit reading. So it would probably go even higher in the next scale.

I expect the voltage to be higher than rated because the 12v rating is expected to be a measurement under load. But my whole point is to check whether it is safe /before/ driving the appliance. Seems strange how the volt reading kept increasing. Is that expected? Is there another test I should do?

Update

It was a lousy DMM, apparently. I retested later (again with no load) and it started at 15v and climbed up from there. That was with a tiny pocket-sized DMM. Then I tried a “Rigid” true RMS meter which gave a steady 12v.

My drip maker shuts off. This is very frustrating, since no human should attempt the consumption of six cups of coffee within thirty minutes.

I'd like to get rid of this timer, but I can't see anything obvious on the board. Is it most likely to be in that little processor at the top left of the coated side?

lmao some of these replies are exactly the sort of thing you'd expect from reddit in like, 2011. For reference, even mildly scalded coffee tastes better than that instant shite, and I'm not drinking ut for taste.

I got a used ultrasonic cleaner with liquid damage for almost nothing and I am trying to repair it. So far I've confirmed that the board has a short circuit between live and neutral somewhere after the relay. Also, while reverse engineering it, I noticed something that seems weird. When the relay closes, it adds C3 in parallel to C2, both feeding the logic circuitry.

I am helping a friend to repair her amplifier. A different friend took a look at it, and they were able to identify the circled part as being the one to blame. However, apparently this is a part that was made specifically for this amplifier and is no longer made, so my task is to figure out what to do. I have some electronics expertise, but mostly I was recruited because I am good at finding things.

However, it would be a good start if I knew what this component was. I've not been able to find it in any of my reference materials, so I was wondering if y'all might be able to help. The person who identified this part is not able to help clarify, as she's off the grid for the next 3-4 months.

(On the off chance that someone here has some specific expertise on this particular amp, it's the Kenwood KA-3020SE)

Edit: Now that I know it's a potentiometer, the biggest challenge is understanding what 200KBH what is necessary to replace the part. It's a 200kΩ one, that's straightforward enough. It also seems that the "B" means linear response (found by checking my electronics reference book section on potentiometers, and cross referencing with other balance control pots for other amps, which specifies linear). I'm puzzling about what the H could mean though.

The big challenge, I'm told, is finding a part that will physically fit. There are 6 contacts on the part, which means it's a dual ganged potentiometer. However, most that I can find online have the pins in a 2*3 arrangement, like this, whereas this one is 1x6, like this.

I recently got a nice office chair for Christmas with heated massage functionality and it uses a barrel plug to power it but I have to be super careful to not pull it or damage the barrel connector in any way. I wish there was a magnet conector for these things in case of a yank pull and was wondering if anyone had heard of some adapter like the one I pictured above.

So I have an idea of a habit builder (also I think it would be fun to build)

Essentially, one piece tracks the habit, and one piece unlocks doors (small, in a grid) based on habit trend. Inside each door would be a "prize".

My question is about the small doors.

• Is there an example of small unlocking like this I can use to expand to multiple doors?

• The idea is there might be more doors than pins on the microcontroller. Is there a board I could put inbetween, or a special technique since they are on a grid, to accomplish this?

I have a Roxim Z3EK bicycle headlight. This light is supposed to have a low and high beam function, but I can only get the low beam to work. So far, I have tried:

• grounding the green wire
• sending 12V+ to green
• sending 12V- to green
• bridging the green and black wires
• bridging the green and white wires

I emailed the manufacturer asking for a wiring diagram, but no response.

I appreciate any guidance y'all might have. Thanks!

I could really use some help getting oriented on a project that is intended to be used as part of a Christmas / White Elephant gift tomorrow.

The idea behind my project is essentially that when a wire is cut, music plays from one of these “singing card” programmable speaker module. The one I have uses a 4V lithium battery cell.

I already have the programmable speaker module configured to immediately play music as soon as its power switch is moved to the "on" position.

In exploring possible ways to go about this, I realized that what I am effectively doing is building a tripwire circuit.

The examples I found were very simple, involving an NPN transistor (2n2222), 10KΩ resistor, battery, and DC Piezo speaker.

In my case, there’s no piezo - I'm trying to handle the entire load that would otherwise be running through the on/off switch.

With my initial attempt, I wired +4V from the switch to the transistor's collector and then separated the collector from the base with a resistor. I connected the emitter to the pin that, when the switch is engaged, would send 4V through and power the module.

Initially, all I got with the “Tripwire” disconnected was rapid clicking from the module's speaker as it cycled on and off. I reduced the resistor to 1KΩ and then 510Ω to get longer runtime, but it was still restarting. I jumped down to 22Ω and that stopped the restarting while introducing a new concern: that resistor quickly climbed up past 100C while the “tripwire” was connected. Without the tripwire, the I don’t want to start a fire, nor do I want the battery to die while this all sits in a box.

Someone suggested that what I actually needed was a MOSFET, so I ordered a hobby kit with various FETs that would get here in time and am now running into a new issue - I can't get the MOSFETs I have to turn fully on and let current through.

I have the resistor connected between Gate and Drain, +4V going to drain, and the load from the module on Source.

With an RFP30N06LE, I get about 2V output to Source. With an IRF840N, I'm only getting 0.9V.

In my photos, the orange wire is +4V, brown connectors the the circuit that ultimately powers the module, and blue is the “tripwire” that pulls down to GND.

I've attached a couple of the diagrams I have been referencing, as well as one I quickly drew outlining my particular application.

I'm starting to feel like this circuit design isn't actually applicable in this context and that what I am going to end up needing is something far more complex that involves parts I don't have on hand. At the same time, I'm worried that I'm about to give up when I'm only a small adjustment away from success.

EDIT / Update:

So far, I have been trying to place the load (full speaker module) after the emitter or source, depending on component used - mostly a limitation of trying to set up the circuit to bypass the on/off switch.

I shifted my attention to just the speaker itself. The good news is that I had success with both NPN and MOSFET, however the audio quality gets so degraded that this approach is not viable.

Update 2: Went back to the NPN Transistor, found a sweet spot at 330Ω where the speaker module does not reset. Resistor seems to stabilize at 40C. Probably going to roll with this and see what happens, try to plug in batteries just before delivery so I can avoid the situation where the battery has died before the right time.

Hi,

I am thinking about the best way to transmit 5 single ended signals from one board to another as well as ground and 2 power rails. I was thinking cat5e cable with a standard rj45 plug but as cat5e is twisted pair I'm concerned about crosstalk.

The cable between the two boards would be a maximum of 50cm. 3 of the signals are addresses for a multiplexer that would change at a maximum speed of 2ms per change. One of the other signals is a 20khz pwm signal. The final signal is a zc detector for mains so max Freq of 100/120hz.

There may be high current switches at ac line frequency (50/60hz) near by.

Would single ended transmission with cat5e cable be okay for this or would I need differential signalling? If I need differential signalling, what sort of cable/connector could I use?

Any help is appreciated

Thanks

Hello guys,

I am planning to build a weather station as an electronics project. It is supposed to be a couple sensors (temperature, humidity, air quality for example) connected to a microcontroller (probably via I²C, because I'm currently interested in that and picked this project as an excuse to do something with it), and a basic LCD display to show the current data.

For this I want a small microcontroller that can collect the stats from the sensors and show them on the screen, so nothing too fancy. I want to actually deploy this on my balcony, so I don't wanna sacrifice a Pi or something along those lines. Ideally something with a sleep mode so I can run it off a button cell. In order to use I²C and an LCD screen I would need around 9-13 pins, depending on the LCD. Plus some additional pins for buttons, means something with at least 16 GPIO pins would be desirable.

I was eyeing out something from the ATtiny family. Ideally it would be a through-hole-mounted chip as I want to use it on a breadboard first (and probably permanently). The only DIP chips are fairly old tho so I'm not sure if they're easy to use nowadays. We used an ATtiny461A in university and had to program it via a Windows XP VM, which is an experience I would not like to relive.

I'm not afraid to get my hands dirty writing raw C code without an stdlib.

While the WiFi functionality of the ESP32 is appealing, I don't know if I want to condemn one of them to a life on the balcony. I would rather use them for one-off projects instead and use something simpler for a long-term deployment.

The following are some ideas I have that I might want to add to my project later, but they're just optional features and I don't necessarily pick the microcontroller based on them:

• Tracking/Logging sensor data over time, e.g. hourly. This would require some fairly accurate timing in order not to drift
• Networking, so I can access the data via my local network

If there exist microcontrollers that fit my criteria I'd be happy to hear about them! I'm not an absolute beginner to electronics, but I've never shopped for microcontrollers before.

Im working on a board for controlling a few linear actuators. They will at full load draw something like 10A, and will be powered by a 24V (or so) LiPo pack.

I have a few H-bridges and as expected when the power is cut off, there is an inductive kickback of about 10A. No PWM, they will be turned on and off occasionally only.

I havent been able to fibd anything on if a LiPo pack would be able to take this reverse current, or if it needs some sort of protection. It also lasts for quite a short time but I'm new to batteries so I want to be sure its not a problem.

Would apprecaite any help :)

cross-posted from: https://beehaw.org/post/23519524

Working on a project where I essentially need a sizable monochrome display - basically a clock display.

Any ideas where I could source a sizable one for fairly cheap, including a control module?

UPDATE: the commenters' verdict is unanimous: this is not a good idea, because it will damage the iron tip of the soldering iron. Thanks everyone!

These sort of sponges are sold for cleaning the tip of soldering irons:

Now, maybe it's an odd question -- but is there any reason not to use one of these kitchen scrubby things instead?

They are way easier to get, plus they are cheaper.

I'm wondering mainly:

• can you think of a reason why it could be dangerous to use the stainless steel one? (like, poisonous fumes or something)
• would it hurt the soldering iron tip?

I'm always struggling to desolder high heat circuit boards like pc motherboards because they used high heat solder. Sometimes I can get it hot enough that I can mix in some lower temp solder but it's always a pain. I've also used my rework hot air at 500* plus the soldering iron at 500* and gotten it, but that's a pain as I only have two hands. Right now I'm replacing the Nec/Tonkin caps on a ps3. Fortunately removal is simple with a chisel, but getting the pads ready for soldering is a huge pita.

Given the endless problems with attempting to properly initialise ALSA with the qualcomm chipset in my device, I've resorted to the idea that I'll be designing a larger case, with a larger screen (and hopefully no shitty curvy corners) and an integrated DAC with probably a small headphone amplifier.

Ideally, I would like this to be addressable, and have the facility to run an equaliser on-board that can be configured via the USB connection, although I'll settle for bluetooth if the former is too complicated. It will also need to fit inside the phone housing (which will likely be around 9-10mm). I plan on an aluminium frame, so heatsink facilities should be easily manageable. The USB connection will, of course, need to be a passthrough connection to facilitate charging the phone - having a separate USB-C socket on the board is fine, I can probably adjust for this.

Am I setting my aspirations too high, or are there components available that meet these specifications?

This is from a section on why decoupling capacitors should be attached to CMOS chips. It shows current spikes during transitions. Which then because of the inductance of traces connecting power to the chip, will cause the power rail voltage to droop.

But why is the ground voltage also shown to rise? What does it even mean for ground voltage to rise when ground is what voltage is measured against?