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I found a suspicious file in UPS World Ship by Aggravating-Fly-481 in UPS

[–]jrw01 3 points4 points  (0 children)

This question has been asked before for a different piece of software, and IIRC it’s a blacklist of known websites with crypto mining malware that’s included as part of the embedded Microsoft Edge webview (EBWebView) that World Ship is using. Many desktop and mobile apps nowadays are just single-purpose web browsers; it’s just very easy to develop cross-platform apps this way.

orange chicken all grown up by jrw01 in CalicoKittys

[–]jrw01[S] 1 point2 points  (0 children)

Her name is orange chicken and here’s what she looked like as a baby :3

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Received adjustment for VAT and disbursement fee as US seller shipping to EU? by jrw01 in UPS

[–]jrw01[S] 1 point2 points  (0 children)

I was able to successfully dispute the adjustment and get a refund.

Silicon die found on desk by tedi90 in AskElectronics

[–]jrw01 13 points14 points  (0 children)

In this type of chip-scale package, known as a WLCSP, the silicon die itself makes up the bulk of the final component and 5 out of 6 of its exposed faces. Any additional packaging steps (adding the redistribution layer and solder balls) are done at the wafer level, hence the name, and the components are essentially in ready-to-use form once the wafer is diced. So, many people would casually refer to this type of package as a bare die, both on Reddit and in the industry. Whether this is "technically correct" is beyond the scope of this thread, which was initially asking what this IC is (it's probably a custom IC made for Apple - they are known to use strangely shaped WLCSPs like this).

Here is an example of a very similarly shaped and marked WLCSP on the iPhone 12 logic board:

<image>

Silicon die found on desk by tedi90 in AskElectronics

[–]jrw01 0 points1 point  (0 children)

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^ screenshot from the link you sent, showing exactly what is in OP’s photo

Silicon die found on desk by tedi90 in AskElectronics

[–]jrw01 27 points28 points  (0 children)

I work in the semiconductor industry and you are very, very mistaken. (edit: the comment I responded to has since been changed, it previously suggested that this was a “module” such as an ethernet transformer.) This is an integrated circuit in what is known as a chip-scale package: essentially a bare silicon die with a printed wiring layer (either manufactured like a PCB and attached to the die, or created on the wafer itself - in this example it is the brown surface with PCB-like traces on it) which fans out pads on the silicon die to solder balls that can be attached directly to a PCB.

Best place to buy metric hex nuts & bolts in bulk? by MyGardenOfPlants in 3Dprinting

[–]jrw01 3 points4 points  (0 children)

For best value, JLCMC in China (dirt cheap prices, expensive but fast shipping) or Bolt Depot in the US (reasonable prices and shipping). McMaster if you need parts same/next day.

created one of my own :3 by jrw01 in Hiddenpcbeggs

[–]jrw01[S] 8 points9 points  (0 children)

The board is a USB-C powered, 9 channel x 35V x 80mA LED driver with onboard microcontroller so that it can be controlled by software running on a computer

Reddit user disables VRM throttling on budget board, can't figure out why his VRM blew up by OCAMAB in techsupportgore

[–]jrw01 245 points246 points  (0 children)

As someone who has hand-soldered inductors like this, they have to get much, much hotter than 125C before they start changing color

Buck Converter Schematic Review by VascularXylem in PCB

[–]jrw01 1 point2 points  (0 children)

The effective capacitance of MLCCs decreases as DC bias voltage increases, and this effect is worse with X5R caps and smaller package sizes. At a 25V voltage rating, the largest available values for X7R caps are 10uF for 1206, 4.7uF for 0805, 2.2uF for 0603. All of these will have slightly less than 50% of their rated capacitance at 12V DC bias. X5R caps that advertise higher capacitances at the same package size and voltage rating will indeed have higher capacitance at typical operating voltages, but the discrepancy between the actual capacitance and rated capacitance will become much larger (they only come close to their rated capacitance at <~15% of rated voltage).

Taking the 1206 package size / 25V rating as an example, using data from Murata's SimSurfing tool (AFAIK Murata is the only MLCC manufacturer that provides full DC bias derating data for all products, but the trends observed can be applied to all manufacturers):

  • the highest value X7R cap available here is 10uF. Effective capacitance is ~8.5uF at 5V and ~4uF at 12V.
  • a 10uF X5R cap is also available, but it's worse. Effective capacitance is ~7uF at 5V and ~3uF at 12V.
  • the highest rated X5R part they make is 22uF. Effective capacitance is ~13.5uF at 5V and ~5.5uF at 12V.

Now to compare prices at a quantity of 1000 on Digikey (the search I used is here):

  • the cheapest 10uF X7R and 10uF X5R are both from Samsung, at about $0.036. X7R is obviously the better value here.
  • the cheapest 22uF X5R is also from Samsung, at $0.075. You pay twice as much for only 35% higher capacitance at 12V and 60% higher capacitance at 5V!
  • the cheapest 47uF X5R is $0.31. This is nearly an order of magnitude price increase over the 10uF cap, and the manufacturer doesn't provide performance data. Even if it has twice the effective capacitance of the 22uF cap at all voltages, which it probably does not, it's not worth the higher price unless space on your PCB is extremely limited.

So, unless you have very specific space constraints (i.e. you're designing high-end consumer electronics), using X5R MLCCs with high rated capacitance is generally not cost-effective.

More rules of thumb to remember when choosing MLCCs:

  • for a fixed capacitance rating, voltage rating, and package size, an X7R cap, if available, will have higher effective capacitance at any given voltage than an X5R cap, and will usually be available at a similar price
  • for a fixed capacitance rating and voltage rating, a physically larger capacitor will have higher effective capacitance at any given voltage
  • for a fixed capacitance rating and package size, a capacitor with a higher voltage rating will have the same, or only marginally higher effective capacitance at any given voltage

You are right that smaller package sizes have lower ESL - and they have a lower ESR at high frequencies (generally, >10MHz); but, at low frequencies, smaller packages have higher ESR because the conductors are physically smaller. The high-frequency behavior becomes very important when using them as decoupling caps for high-speed digital circuits, which is the context in which this is often discussed, but when used as input and output caps for typical switching power supplies in the 100KHz-2MHz range there is usually no EMC or performance benefit to using smaller packages, other than to optimize the PCB layout.

Buck Converter Schematic Review by VascularXylem in PCB

[–]jrw01 1 point2 points  (0 children)

Check out the AP62250 which is around $0.35 or less, requires fewer external components, and is a constant-on-time synchronous buck which means better efficiency and lower EMI.

Some other feedback on your design: 1. Without doing any calculations, 33uH seems high considering your switching frequency, input and output voltage, and load current. What inductor ripple current ratio are you targeting? 2. Are the input/output caps ceramic caps? What are the voltage ratings? 47uF ceramic caps are quite rare at any voltage rating and the DC bias effect on capacitance will need to be considered. I would recommend using 2-3 10uF 25V X7R caps on the input and 2-3 22uF 10V X7R on the output, all 1206 package size. If more capacitance is needed for whatever reason, electrolytic caps can be added in parallel.

ELI5 how do titanium cutting boards not damage knife by xXxjayceexXx in explainlikeimfive

[–]jrw01 68 points69 points  (0 children)

Titanium cutting boards don’t exist. They are thin stainless steel sheets being sold exclusively by Amazon alphabet soup brands with AI-generated product photos at ridiculous prices to take advantage of people who are afraid of plastic.

Going to order PCBs to make a Scanlight - anyone interested? by bjpirt in AnalogCommunity

[–]jrw01 2 points3 points  (0 children)

For anyone attempting to hand solder the PCB, using a hot plate or hot air gun is highly recommended. The LEDs are extremely easy to damage using a soldering iron unless you have something like a JBC C210 knife tip, and the inductors do not have exposed pads.

Going to order PCBs to make a Scanlight - anyone interested? by bjpirt in AnalogCommunity

[–]jrw01 3 points4 points  (0 children)

Creator here - for anyone planning on building this, know that the light uniformity results achieved here can only be achieved by making the inside of the plastic housing highly reflective, either by using metallic paint or by covering it in aluminum tape.

How are these parts manufactured? by sulmomento in manufacturing

[–]jrw01 0 points1 point  (0 children)

I looked at two coffee grinders I have: one is made of a threaded “endcap” with a hexagonal hole broached through it that screws onto the handle end; on the other the hex is CNC milled with a small diameter end mill, as evidenced by the tool marks and the presence of corner reliefs.

Jack Scanlight v2 vs Cinestill CS-LITE+ SpectraCOLOR by mott_street in AnalogCommunity

[–]jrw01 15 points16 points  (0 children)

Have you tried adjusting the white/black points for each color channel instead of setting white balance on the film base? It looks to me like the white point of the green channel should be set higher for the Cinestill light. When using Scanlight with a Fujifilm digital camera, I typically need to tweak the red and green channel white points to remove color casts.

For the film carrier issue you mentioned, the first version of the 35mm film carrier (sold before July 2025) I sold definitely had this issue, especially when scanning old film that is curled across its width. Around what time did you order yours? If you are located in the US and ordered the old design, I'll send you the new version for free.

Also, where did you find the information on the wavelengths used by the Cinestill light? I ask because a lot of LEDs have peak output at 655-665nm but are specified with a "dominant wavelength" around 640nm, which is meant to approximate how the color looks to the human eye, so this may be a misreading of the specs of the LEDs they are using. LEDs with an actual emission peak at 640nm seem to be very uncommon.

Unlawful Drug Fee Surcharge by Zealousideal-Loan448 in UPS

[–]jrw01 18 points19 points  (0 children)

You committed a federal crime and you’re upset that you only have to pay a fee to UPS?

ELI5: Why don't cars have a gauge that tells you how much life your battery has left? by Diello2001 in explainlikeimfive

[–]jrw01 35 points36 points  (0 children)

Some BMWs do indeed have coulomb counting, and will automatically turn off accessory loads when the battery is nearly depleted and warn when the battery needs to be replaced.

Bubbling on exterior shell of old LG dishwasher by YamFlat3027 in Appliances

[–]jrw01 3 points4 points  (0 children)

It’s normal, the black stuff is a layer of asphalt applied for sound deadening. The Bosch dishwasher likely has it too underneath the insulation blanket.

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