Hello Lemmings, Hope you guys are doing well.

Objective: Open the door automatically through HomeAssistant

My Plan:

1. Use an ESP32 and flash ESPhome. Wire up Servo Motor (SG90) with ESP32. Tie a thread on between the Servo Motor Arm and the physical latch (physical latch that I can pull to unlock the door) such that when the servo motor turns from -100 to +100, the latch is being pulled to cause the door to be unlocked.

2. I am planning to power this using AA Cells + DC DC Boost convertor.

Issue:

1. How do I mount the Servo Motor on the door?
2. Is there any other (read better) way to achieve the same result?
3. Would you recommend any power source other than AA Cells?

Image for reference:

The latch has a keychain-like loop where the thread is tied. To unlock the door manually, I pull the latch towards right (---->) . This action is planned to be automated by Servo Motor.

This is an idea that entered my mind. The traditional way is applying some etch resist like toner or dry film, etching away the copper and then adding solder mask before populating the board with components.

Can the solder mask be used as etch resist instead? It feels like skipping an unnecessary step in the process. Why isn´t this more common? This way you won´t need the step of removing etch resist only to replace it with a slightly different compound.

Ever since I've gotten into Retro Computing, I've been confronted about things like soldering, Circuits and Electrics in general... and it has made me want to try experimenting with my own ideas!

That does however mean that im still pretty inexperienced and thusly don't have anything to actually experiment with either.

So what kind of Breadboard Kit will give me the best and most things to start getting into this Hobby?

It appears to me that UV resin, used for SLA printers should be quite convenient for making PCBs with a laser etcher. You can spread a thin layer of resin on the board and quickly expose it using a laser engraver. It should be most convenient for silkscreen layers that are otherwise difficult to apply.

I think the common method of applying UV mask and spreading it using a piece of plastic sheet is messy and I can never guess how much resin to apply. It's always too much or too little and it's always unevenly spread. And then the UV light exposure is another guessing game.

I have a 500mw 405nm laser module attached to my 3D printer and could easily 'print' some PCB layouts on a thin layer of SLA resin.

Does anyone have experience with this?

Hello,

I'm creating a BoM for a youth group project. We're planning on building the Electromagnetic Ring Accelerator from Hyperspace Pirate. He's provided the 3d print files, but not the finer details on wire gauge, enamel wire gauge and ball size. I also want to confirm the photoresistor. Are there different photoresistors with with different sensitivities or ranges?

I've included the wip of the BoM.

Hey guys i cant find any usefull guide on how USB c charging works in depth. In particular i have bought a pair of Sony headphones which i would like to make wireless change so I also bought a crappy wireless coil meant to convert a phone into wireless charging. i opened the headphones, located the ground and 5v pin coming from the USB connected the circuit and surprise the charging led doesn't light ... The charging board is separated from the main board so I checked the flat cable that connects them, found the 5v and gnd ,spliced into it, and the led light lit as if it was charging. the next morning the led was of signaling the headphones are full, unfortunately after powering them on the battery status indicated was still 20% as the evening before ... Have I done anything wrong ? What about that phase when they negotiate the power output with a magic resistor ? What should I try next? Thanks in advance 👍🏻

Greetings again! Yesterday I posted the schematic for this circuit, and today I have routed it as a 2 layer PCB. The intent of this board is for it to be a playground to build autonomous LED animations with the LP5812 ICs from TI, which seem pretty neat.

I'm hoping to get feedback on this design and sanity checks to make sure I haven't missed something when routing this out. I couldn't figure out how to upload multiple photos, so I'll add some more views in the comments. Cheers!

If you're interested in the KiCad files or other related things, I've got it on GitHub.

Seriously, what sadist saw a flat PCB surface, flat pick and place machine heads, and said "lets create a round component"?

Joking aside I am genuinely curious what advantage the MELF design actually offers. I know they're a pain to get a machine to place properly, they have more solder flow issues than components with flat leads, and they seem like they would be harder to manufacture too. So why a round component? Anyone here have any insight on why they even exist?

Greetings! I've been throwing this schematic together as I want to experiment with the TI LP5812 IC which is an i2c controlled autonomous matrix LED driver. I am a novice when it comes to electronics so I'm looking to see if I've missed anything in this demo board schematic.

The intended purpose of this circuit will be to provide a playground to experiment with different lighting patterns by allowing the user to interact with two of these LP5812 ICs over i2c as each can only drive 4 RGB leds each.

My main points of concern: Making sure that I haven't missed anything critical in the rather dense TI datasheet https://www.ti.com/lit/ds/symlink/lp5812.pdf?ts=1710689049125 as well as making sure that my schematic makes sense.

I chose not to include i2c pullups on this dev board as I felt that was best left for the host to configure, but I'm happy to learn. Thank you!

Here's a link to the KiCad project if you'd like to see more https://github.com/scytherswings/Starlight-LP5812-Dev-Board/tree/main

Besides putting too many devices on a single wall socket, that draw too much power, what is supposed to happen?

Like say I chain ten dividers and put a single vacuum cleaner at the end. Is that more dangerous than plugging it directly into the wall?

I have a Mission MS 200 Subwoofer where the power supply has stopped working. I was quite happy with it, and would like to try to fix it, also I don't have the money for another. I have taken it apart and have narrowed the fault down to the PSU. I have visually inspected the solderings and components, and nothing obvious is wrong. I am not good enough to be able to reverse engineer the board, and was hoping there might be someone here with access to a schematic? Failing that, any pointers on where to maybe do some in-circuit measurements to narrow down which part(s) might be broken, would be very highly appreciated!

I'm trying to understand what's happening in this circuit:

I------------------T1 (+333V)
I                 I
I                 R1(10K)
(pos)             I
1000V             I------------gnd (0V)
(neg)             I
I                 R2(10K)
I                 I
I                 IT2(-333V)
I                 I
I                 R3(10K)
I                 I
I-----------------IT3 (-666.7V)

I am learning basic DC theory from reading and sometimes I come across something I'd like to ask a question about, so:

1. In the above circuit, without the ground, the voltage across all components would begin at 10V and finish at 0V. By adding a ground, I'm basically saying "here is 0V" and everything gets redefined in reference to that point and I end up with a 10 volt circuit with +3.33 as it's highest voltage and -6.667 as it's lowest.

2. The electrons could care less, they still flow from the anode to the cathode of the battery under normal conditions, going from the highest potential to the lowest.

3. This example was only used to demonstrate voltage dividers. It revolved around worker protection present in aluminum processing. Each machine is in series and mobile grounds are used nearest the machine a worker is using. I assume that this allows the worker to have the least exposure to electrical shock as they are also at ground potential?

I actually think working though these questions has cleared everything up, but please, comment on anything I got wrong.

Also, sorry about the crappy drawing, the autowrap in this editor really made things tough to format

Thanks!

I want to build a linux(yes i want linux specifically or a deritive of it) smartwatch as a prototype that lasts ~24 hours. Ive been looking for chips that are small and power effient enough but most of them cant run linux. If i have a 400mah battery that gives me a power budget of about 60mw... I know its possibly because there are wearos(basically android) watches that last 3-4 days. I dont know what kind of sorcery that is but that means it consumes about 15mw??? I really do feel like im miscalculating something but i checked multiple times. Do they hibernate linux/android and run it off of another chip. I also dont know how to excecute that properly and its kind of off topic of my question. So point is linux on a ~60mw budget in s smartwatch. I want to use a mip display as i really like the look and it uses little power but if ever want a heart rate sensor in it thats even more power consumpotion. Thanks in advance i guess if a saint answers this shitstorm of a question.

It happens rarely, but I will notice either my phone or the charger getting pretty toasty randomly. What could be causing this?

cross-posted from: https://sh.itjust.works/post/13637559

Hello everyone, I need some advice.

I am making custom PCBs for a project of mine. It's basically for a little remotely controlled robot using little DC motors. I chose the Seeed Studio XIAO ESP32C3 as the uC since it has inbuilt wifi/bt, 3.3V regulator that I can use to power the motors (can source up to 700mA) and lipo charging management (the robots will run on battery). As you can see from here, the microcontroller is surface mounted and the pads for the battery are on the bottom layer. Same story goes for the thermal pad of the microcontroller and the thermal pad of the motor driver (datasheet). I have worked with SMD components in the past and can solder them by hand, but I have never worked with SMD components that have thermal pads on the bottom layer. My question is: how to manage (route?) them? My PCB is 2-layer and I was planning on having both layers filled with a ground plane. Do I just connect thermal pads to the ground plane and call it a day? Wouldn't that make the components hard to solder with hot air? Do I make an isolated polygon that only acts as a thermal pad?

Speaking of soldering is even hot air the way to go in this case? My PCB has components on both sides, and I was planning on ordering stencils together with the boards and using solder paste, placing the components and then using hot air to solder the components in place. I thought a hot plate would be better but I don't have access to one and I don't know how that works with components on both sides.

I attached some photos of the PCB in Kicad, and here's the git repo. If it is of any help, I'm planning of having them manifactured by JLCPCB. It is also my first time using KiCad, so go easy on me :)

Thanks!

I work on equipment that runs off 3 phase 208V but it uses uses a transformer to drop it down to 120V for most of the controls. On this equipment I noticed that there are two fuses on the lines exclusively feeding the 208V side of the transformer and a fuse directly off of the hot side on the 120V side of the transformer.

Isn't the fuse on the 120V side of the transformer redundant? From my understanding, if there is a current spike on the 120V side of the transformer then that will cause a current spike on the 208V side of the transformer and immediately blow those fuses anyways. Is this just a certification thing where that redundancy is required? I'm in the US but this equipment does also get shipped to various overseas locations. Also, while it isn't standard, this equipment is capable of passing a TUV inspection if a customer requests it so I'm not sure if the potentially redundant fuse is just a TUV requirement.

Working on a joystick. Seems like any protocol I use to read from peripherals is going to be bottlenecked by having just one input. My microcontroller might have multiple ADCs, but there's just one processor stepping through them. Same for spi, or i2c, or uart. There's really only ever one sensor reporting back its data at a time.

I know this might not matter for measurement resolution. Especially if you're polling at like 115k serial or something, but...

That's 8 bits per axis, and three axis. Now that's at least 34 bits. To sample each axis we're down to only 4.5k samples per second. Plus whatever other cycles the controller has to handle... even if I spent half that time doing microcontrolle cycles at like 2k we're probably still well with the best star craft apms or whatever. I'd still like to find some way to really over engineer this thing.

I read a little about tdm, but that's out of my league and I don't know if you could even have 3 simultaneously signals that way

I'm thinking a microcontroller for each axis, and a usb port for each of them. So it appears like 3 different controllers to the computer. The user would just have to map the axis from the 3 controllers into 1 in their game software. I assume the steam remapping could do this.

Is it just going to get smashed back into one thread in the computer's usb hub anyway?

Any other suggestions?

I've recently bought a used computer, and it has a few problems. I'm looking for a guide to help me identify which parts are causing the problem.

I've tried to watch and read a few guides on how to build a pc, but they haven't given me any information on how to identify broken parts.

I'm interesting in a guide, but I'll also post my specific problems, if any of you know how I might fix them ^^

the problems I'm experiencing are the following:

the screen will sometimes glitch out with black areas when watching movies, but only when in fullscreen. The problem usually disappears for some time when exiting and re-entering fullscreen mode.

The computer won't run certain drivers and sometimes when powering off, the computer will use a long time closing certain applications, but will fail in the end and I have to power it off manually. Also, it will sometimes reset my settings. Back to factory wallpaper and factory everything. it remembers my users and my applications.

I've grouped them into two paragraphs, because I have an idea, that the graphical problem might be caused a bad GPU.

I have no idea, what's causing the stuff in the second paragraph 😅

also, I hope this is the right community for this question - I couldn't find any communities specifically for computers.

any help is welcomed ^^

//EDIT:

Thanks for the help :))

I removed the gpu and now only use the integrated graphics in the cpu, and the visual glitches are gone :))

I've run some tests on the computer (from the boot screen), and it seems the memory is fine. The only driver I know to be a problem is the driver for my WiFi usb. I'll try to work on that, or maybe I'll buy a WiFi card and pray that works better ^^

thanks for the help :))

//EDIT2:

All my problems are fixed now ^^

the wallpaper change was because I am a doofus and forgot that I had made a new user on the computer, which of course had the default wallpaper 😅

the driver problem was only with my WiFi adapter, and I fixed that by removing the current driver (rtl8812ub) and installing another driver (rtl8811au), which fixed the problem :))

thanks for the help :))

Hello altogether, I guess everybody has some USB-C cables lying around, but wonder if it's 3A, 5A, 3.0, TB... Anybody able to recomment a device able to determine that? Maybe also something that can be combined with a load tester.

I got these TP4056 modules from an AliExpress vendor and fail to understand how the protection circuit works or if it's just typical Ali shovelware. It could be my limited understanding of electronics.

The protection circuit appears to be just for show. To the right there's a DW01S chip that prevents over charging and discharging in combination with the 8205 dual channel MOSFET.

It looks like the drain of this MOSFET isn't connected anywhere. I've tried following the traces using a multimeter and no other pin shows continuity with the drain. Source1 is connected to Battery - and Source2 is connected to Terminal -.

I suppose the Drain starts participating in the circuit when one mosfet activates.

What was the idea behind this? That the 8205 acts as an AND gate by having them both in series?

I'm trying to make an 18650 testing circuit that uses these modules to charge and discharge a battery and wanted to use the protection circuit mosfet as a trigger for discharging.

It's an SPST-NO micro switch. Don't waste time searching for it. I already wasted mine. Just let me know what it is if you know it off the top of your head. 😊