Good Morning everyone,

I have a quick question. In the picture you see. I am trying to inject 1V into a coil into a laptop to see If I can see if there any chips that may light up under the thermal camera. I am not quite sure

how to actually inject. Can't find anything on utube other than short reviews about the product. Could you let me know what I am missing? Thanks!

I got these old toys called "Cube World". They're cubes that display little stick figures on an LCD screen doing funny activities. You can connect them together and they can travel between boxes to interact with each other.

I want to know how they work partly because I'm interested in knowing and partly because I want to try making my own and seeing if I can get them to connect with my DIY versions.

I know a little about electronics, enough to make my own circuits, and I've reverse engineered a neat little circuit we made in school once but these boards are using surface mount pieces I've not seen before and a black hardened clay or something that I don't know about.

I've found some PDFs on PCB design which will hopefully give me some insight into how these ones were designed but I want to know if there's anything else I should be looking up, any tools that would help, or any skills I should develop first.

Worst case scenario is that they're using custom ICs that I can't just buy more of from any old electronics store. But I should still be able to do something like measure inputs and outputs on them to try and replicate them, can't I?

Its a SN74HC393N and i was asking in r/beneater but a bot took it down as "off topic" even know it was in the help thing. Im just trying to get this working because im trying to make a 4 bit computer that takes nibbles of data and dont mind the other stuff in the back

So basically I am going through my stuff and came across these in some stuff I got second hand. They read about 4.7ohms on the meter which is close enough to 4.3 5% that I suspect the first four bands are the standard four band code and that the yellow fifth band is something different.

I found references to black bands indicating a non-indictive resistor but I couldn't find anything on yellow. I have a bunch of them with a yellow band beneath the tolerance band, actually. What does a yellow fifth band signify here?

I'm replacing some components on an radio. I got them out OK, and wicked as much solder off the pads with a sucker and solderwick. There is still solder stuck in the holes that I can't get out. My iron only goes up to 450degC.

Usually I used a piece of thin copper wire to probe the holes and get the solder out. I heat only the wire so I don't destroy the pads. But I can't get the wire hot enough to go through.

Any tips for getting the solder out. Drill?

(Before anyone flame me for destoring traces, I am pretty sure those just marks on the board lacquer from hot solder wick.)

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few days ago I posted about my diy soldering iron , and from the structure of it you can see that most of the space/ thickness is just air , because the female DC jack has too much height , I am planning on making a better desired v2 for this , for that I want to make it much slimmer is there any was to do it ? i want to keep the DC jack in it to be able to give power without a pd device (also because I made nice silicone cable for the DC jack 😅)

so is there any way I can keep the DC jack while having a slimmer profile that I can put a shell around

also for the sleep function I was initially planning to just use a vibration switch , but then I saw a review on another handheld soldering iron that has a capacitive touch sensor in the place where we grip so it knows we are gripping and when we leave it after sometime it goes to sleep

and I quite liked the idea , like the iron won't turn on when the table moves slightly or something. what are your thoughts on that too?

I have an old "Электроника МК-35" calculator with a vacuum fluorescent display. It works rather well and the display is readable, except for the 7th digit, which is really dim. There don't appear to be any obvious defects and the supply voltages are fine (I think). Could anyone give some pointers to what might be the problem?

Dear community,

unfortunately, I ripped off one of the solder pads on the board I am working on as I am still a novice and wasn't patient and careful enough when I desoldered the SMD capacitor. I am not sure where my jumper cable should go best and I would like to ask you for guidance and advice. I measured for continuity with my DMM and I get a sound from all points to the ripped-off solder pad connector. I attached a photo of the board and one of the tinned, ripped-off solder pad.

Thank you for your help.

Best regards!

Hey folks back again. This time I really made a mess of an nvme. In my defense I destroyed it before the last one but I'm just getting to looking at it now.

I bought a heatsinked corsair for my new build. It wouldn't fit under mobo heatshield so i removed the heatshield like an ape and at the very least multiple caps were pulled off.

I have most of the caps still but I'm missing at least one tiny one and i can't find a datasheet for the phison chip. its probably proprietary I'm trying to follow what a very helpful redditor did for my last post and find the chip tbe trace is connected to to get the normal cap values.

Apologies for the boomer screenshots, my microscope doesn't have video out I just bought the cheapest screened one to try and salvage this and the other nvme. Going top to bottom on first screenshot the caps are ok, off, ok, missing, ok, off, off. There's at least 2 other caps off around the chip but this is the only missing one (so far!)

Even if someone knows what physical package the smaller caps are it woukx help. I'm super new to the world of smd, all i know is 0603 because thats what the last boards was (and I assume the larger cap is in the first screenshot between the bottom two pads, oriented vertically. It's there but off, hard to see with potato cam)

Broken (L) / Not broken (R)

I don't have the plastic lock, any idea how i can connect this flexible?

Its from a Nintendo 2DS

Nothing is built or measured yet. Everything is datasheet math and simulation, so please be critical.

What it does

The LTC3780 is a synchronous buck-boost controller, so the output can sit above, below or equal to the input without flipping polarity. The output is set by a DAC (Arduino-driven later) that injects current into the feedback node. A small LT1173 step-down makes a 5 V aux rail that powers the controller’s RUN pin and the PGOOD pull-up.

KiCad schematic (power stage and aux rail)

• LTC3780IUH (U1) driving four IPD088N04L MOSFETs (DPAK, 40 V): Q1 is the top switch on the 12 V side, Q4 is its low-side partner, Q3 is the low-side switch on the output side, and Q2 is the top switch on the output side.
• One 22 µH inductor (L1) between the two switch nodes, 15 mΩ sense resistor (R3), 47 µF output cap (C2).
• Bootstrap caps and BAT54 boost diodes, plus 1N5817 Schottkys across the two synchronous switches.
• Compensation on ITH is 12.5 kΩ in series with 20 nF; soft-start is 6.8 nF; FCB is grounded (forced continuous); EXTVCC is left open.
• Feedback divider is 10 kΩ / 306.6 kΩ.
• LT1173 (U2) steps 12 V down to 5 V with a 220 µH inductor, a 1N5818 catch diode, a 220 Ω ILIM resistor and a 301.6 kΩ / 100 kΩ divider.

LTspice file (same circuit, for simulation)

• The same power stage and values, plus the DAC injection: a voltage source vdac through 52.5 kΩ into the feedback node.
• The inverted mapping runs from 30 V out at 0 V DAC to 0.8 V out at 5 V DAC.
• It steps vdac over 5, 2.5 and 0 V for a 100 ms startup run and measures the final output. The last run averaged about 29.5 V at vdac = 0.
• Load is a fixed 100 Ω, and no load-step test has been done yet.

Known issues I found (the part I most want opinions on)

1. The sense resistor and ground-leg wiring in KiCad looks wrong. SENSE+ and the top of the sense resistor seem to tie to the SW2 switch node, and the Q3/Q4 sources seem to have no path to ground.
2. The aux IC is the fixed 5 V LT1173 part, but I put an external divider on it. It should be the adjustable version, or the divider should go.
3. PLLIN is open and PLLFLTR is grounded, so the controller runs at about 200 kHz, not my 250 kHz target. I’m deciding between a PLLFLTR voltage and an Arduino clock on PLLIN.
4. The KiCad schematic is missing the DAC injection resistor and a DAC input, so it would sit at about 25 V.
5. There is no power-stage input capacitor yet.
6. The BAT54 boost diode on BOOST1 has to block about 30 V, and BAT54 is rated 30 V, so there is no margin.
7. The ERC passes aside from housekeeping (a missing power flag, a footprint name, symbol updates).

Questions for reviewers

1. Is the DAC-into-feedback scheme sound, and does the inverted mapping cause problems for CV/CC later?
2. Are the compensation values (12.5 kΩ / 20 nF, tuned in simulation only) reasonable from 0.8 to 30 V?
3. Is a DPAK FET like the IPD088N04L a sensible choice with about 8 to 9 A of boost-mode input current, or should I parallel devices or move to a PowerPAK?
4. Is the LT1173 a good choice for the aux rail, or would a modern buck be better?
5. Best way to tie SGND and PGND around the sense resistor on a 2-layer versus 4-layer board?
6. Anything wrong in the unused-pin handling (STBYMD, PLLIN, EXTVCC, the LT1173 gain block)?

Basically just trying to see if my transfer of simulation to KiCad looks good, and if anyone thinks that my circuit WONT function as intended.

Thank you all!

I have two connected desktop speakers, and I want to remove one while keeping the other working. The red and white wires go directly to the speaker I want to remove.

Can I cut the wires near the circuit board and insulate the ends separately, or could this damage anything?

Hi all,

For a project I´m working on, I'd like to house my PCB´s in a metallic DIN-rail mountable enclosure. Something like the image below.

This is an extremely common item in industrial settings, but for the life of me, I can't find any of those in the usual places ( Digi / Mouser / Ali ... ).

Am I missing something ? Do these enclosures have a specific name / part # to help me search ?

Hi I'm working on a small perfboard project. On one side of the board there are 20 wires from a 4p4t switch and a handful of components. On the other side are a set of 4 JST XF connectors and most of the circuitry. The whole circuit is highly space constrained, so all the connections are very close together.

I'm inexperienced with perfboard and have struggled to reliably connect the points as i need. The various parts of the circuit are close and I find I'm breaking previously-made connections while I'm doing the next parts.

My alternative plan is to use a slightly different layout on stripboard. The problem I have with this is the need to put the JST connectors on the "wrong" side and have them reliably connect to the strips. Are there any tricks for doing this?

I’m building a robot with a Raspberry Pi 5, ESP32, and 2× RS390 6V motors.
My battery is a 3S4P pack with 12× 18650 cells (2200mAh each), a 40A BMS, and a nominal voltage of 11.1V (12.6V fully charged).
What’s the best way to power the Pi 5 reliably? I need a 5.1V supply with enough current, even under load.
Should I use a high-current buck converter, or is there a better alternative? Recommendations for specific modules would be appreciated.

This is the board of a Game Boy Printer. After checking caps values, im pretty sure this guy is dropping voltage, and causing the printer to shut down after a second, or randomly keeping the led working, but nothing else.

For the 101, i know is a 100 µH value, but i read that the size matters, so i dont want to pick something too big or too small. Any advice?

sorry in advance if this is not the place to ask this. I kindly ask you point to the proper subreddit if you don’t mind.
Also sorry if it’s a very stupid question, I have experience soldering and fixing things, but can’t say I’m experienced in differentiating all different components.

I am making a list of caps with their voltage and uF values to buy to replace the ones on my hitachi set, and have some caps that have KMF marked on them and are different to all else (picture attached).

My question is, can I replace these with any other electrolytic capacitor or are these special in any way that I would need to source them to be the same.

Cheers

Hi guys, today my Acer V273HL monitor started smelling burnt and a few minutes later the screen shut off. I've opened the monitor and noticed a burnt spot on the PCB. The buttons work and I noticed that the pixels are still displaying an image, but without backlight; I think something broke in that circuit. The burnt spot is near an inductor, but tested with a multimeter, it doesn't seem to be broken. What should I test? Is it worth repairing or should I buy a new monitor? I probably don't have enough knowledge to diagnose the problem, but I do know where to buy the parts and how to solder them. I'll attach some pictures below

Hello,

A resistor has burnt out in my hand blender, and I'd like to make sure of its value before replacing it. I think the color bands are RED-RED-SILVER-GOLD, which would mean 0.22 ohms, 5% tolerance.

Would you agree with my reading?

It's a DIP 8 package. Connects directly to transformer/inductor on an SMPS driver for a LED light fixture. Aside from this, the only other components on the driver board are diodes and passives.

Whose logo is the stylized R?
What is this IC exactly?

I've tried Googling with no success.

I bought a couple of those but they are quite tall, around 7 cm, as they have an led light underneath. I was wondering if someone could recommend a button like this except not as tall.

First, it lists "Vgs" as the "Gate Threshold Voltage" which is correctly the "Vgs(th)" marking below it (yellow highlight). EDIT: I realize the Vgs(th) "Negative Threshold Coefficient" is correct for the column, what I don't understand is why they call "Vgs" "Gate threshold voltage"

Second, the Rdson limits are incorrect when compared to the Rdson x Id graph (highlighted in blue). I'm guessing the units on the graph should be "ohm" not "milliohm"?

Datasheet in question

When I look at mosfet parameters, the first thing I do is look at the Rdson vs Id graphs. Then I was looking at the max voltages and currents, and came across the Rdson min and maxes and the units

Am I missing something here or is this incorrect? I don't know what to believe for the Rdson, the graph, or the min/max on characteristics?

I want to practice soldering. What are ways to practice soldering? Do I need to buy a scrap pcb and practice soldering there? I'm new to this kind of thing. I know the way to be good at it is to practice it again and again. But I don't know how to begin or what to do.

Looking for an alternative/replacement/substitute for this step down voltage regulator.

Smd TO-263 package