Kmart lied to me, so I hacked their lamp [video] | Hacker News Reader

Kmart lied to me, so I hacked their lamp [video]

youtube.com

https://www.thestockpot.net/videos/whykmart for those who do not want to watch a video like me.

Isn't the use of USB-C promotion without at minimum basic USB compatability disallowed?

I have a few devices which have a USB-A to barrel plug, but they do not advertise anything and afaik that is perfectly fine. And they also only work with a normal USB charger, not the fancy ones.

Kmart DGAF they’re the primary junk purveyors in Oceana.

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Downvoted because he's in Australia and there was no reason for you to bring your personal political axe grinding into a tech discussion.

Yes, it was my mistake assuming he was in the US. I only read the blog post and did not see this was KMart Australia. The poster asking "Isn't the use of USB-C promotion without at minimum basic USB compatability disallowed?" is explicitly a social/political issue. KMart lying about its products is explicitly a social problem thats larger than just one person replacing a circuit board in his lamp. Hopefully there are legal remedies that can be taken in Australia for violating industry regulations.

"Eschew flamebait. Avoid generic tangents."

https://news.ycombinator.com/newsguidelines.html

To be fair, I took a very specific (yes, offtopic) tangent!

> The ESP32 has its own charging circuit.

What?

_reads on_

Turns out, he uses a specific ESP32 breakout board (AFAIK a Lolin one) that includes a charging circuit for a 1S battery. It's a really nice board, but to say that ESP32 includes a charging circuit is wrong, for anyone else curious.

Everyone in the know already understands this.

> for those who do not want to watch a video like me.

Thanks! It made me read his other articles. I liked this one more: https://www.thestockpot.net/videos/3dprinteddownpipe. A 3D printed downpipe. Because that's what the solution he was able to do.

I don't entirely agree with the paint colour. Which is really nitpicking, or said in another way: I'm quite impressed!

Sure but the sheer quantity of goods being imported makes it impossible to verify compliance proactively. You need someone like him to discover the violation and speak out about it (which he has beautifully). Someone could contact Australia's customs service, the USB Forum, or the electronics certifying agencies to get the device recalled and blocked but it likely wouldn't stop another similar item from being imported under a different name and design.

Thank you!

As an aside, while I'm trying to read the page, and it is a fun page, I kept getting distracted by the 'load-on-scroll' images and text.

My eyes kept darting down to what loaded, rather than keeping with the text I'm trying to read

Anyone how does the conic pyramid drill he is using in this image is called and what's its use ? (drilling probably but why the shape ?):

https://images.squarespace-cdn.com/content/v1/67b67e84acd181...

It's called a step drill bit. It's basically a hole saw but for metal.

YouTube features Transcripts for most videos now, including this one. So simply click through to that, and you can read along with virtually anything, including linked time stamps.

I’m rather surprised anyone would want a battery operated lamp at their bedside anyways, unless it was a backup battery for when the power goes out. There’s no battery indicator to know when it is low so you would just have to guess or pay attention when it looks like it needs to be charged. Most people would probably just plug it in and leave it plugged in all the time.

Thank you! I thought I missing something when this wasn’t the top comment. The idea of adding another device that I have to “tend to” is not attractive to me.

> anyone would want a battery operated lamp at their bedside

Thomas Merton could still be alive, if only...

I actively avoid adding to my life devices which require charging. Still at any moment at least 2-3 devices are being charged.

He has it setup to charge whenever he is not charging his phone. So, it's charging during the day and being used at night most likely. I have friends that have used battery operated lights where there aren't enough outlets or to avoid a cord to trip over.

Both the video and related post are incredibly high quality productions. The animated circuit diagram on brown paper in the video is a very approachable way to explain the problem and solution. Nice! And it’s always nice to see some Australia pop up on my browsing.

Agreed. Its a great way to communicate, and shows the person speaking has thought out the process.

I also have such a lamp. Supposedly it's USB-C connection, but it only works when connecting with USB-A to USB-C cable.

My guess is it's due to the requirement to comply with EU law about USB-C. But proper USB-C requires active circuitry but manufacturers don't add it to save a few cents.

This is usually a single tiny resistor in the right place that is missing, which is not a few cents in a mass production, it is just a fraction of a cent. But someone needs to know to actually put it there.

I doubt it: that only applies to equipment with radio capabilities.[1] Also, Kmart is regional to north america, it doesn’t exist in the EU.

[1] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A...

It doesn’t really exist in North America anymore either - down to only 5 stores. This is about the Australian version.

Proper USB-C charging requires no active circuitry. You need a pull-down resistor on both CC lines. Not just one, or your thing only charges if the USB C cable is rotated the right way up.

As mentioned, the requisite resistors are less than one cent each in quantity.

I am really missing an explaination of how the cable and PCB were non-standard and if that would have been fixable. This feels more like building a new lamp for an existing housing than hacking the existing one.

There's a pinned comment on the video about the cable:

    For everyone that's interested, the included USB cable is wired like this:
    
    GND    -------> GND
    D+  -------> VCC
    D-   -------> VCC
    VCC -------> VCC
    
    So it is a non-standard cable! I measured by checking continuity between the USB A plug, and the USB C connector with a USB A adapter on it. None of my probes are small enough for a USB C connector's pins directly.

    There was a bit in the video about this that ended up on the cutting room floor, my bad!

Where do you even get a cable like that? If the answer is "they made it themselves" why go with a USB-C connector then? Seems like any old barrel connector would be both cheaper and easier to work with.

Unless it was really to put "USB-C" on the box.

I was not aware Kmart was still in business.

Don’t think the Australian version has much if anything to do with the American one. It’s huge in Australia. Mostly selling cheap junk.

K-Mart in America also sold cheap junk.

Ah, I totally missed that aspect. In the US it mostly sold cheap junk, too.

Meanwhile I probably would've just returned the lamp and bought a $20 lamp off Amazon that has a proper USB-C charger: https://www.amazon.com/dp/B087CDBKCH/

I guess I'm not a very good 'hacker'.

> I guess I'm not a very good 'hacker'.

It depends. For me, the outcome is a function of spare time I have in the upcoming days. I have written complete tools in a weekend, or written much smaller tools over the years. On the other hand, there is a mount of projects waiting to be started, but I have no time whatsoever to touch them.

Just don't hit yourself what engages you or your priorities is different than the person who's on the video/website you're visiting.

I'm in the same boat, but it wouldn't make a great youtube video of me vlogging my kmart trip and my subsequent amazon shopping spree ^^

Ok, but can you find one that also has homeassistant integration?

That's the real value add with all of the work done. You could also purchase a 1 buck usb-c lithium charging IC chip and wire the outs in place of the broken "usb-c" port and have the original working the way it was "supposed" to.

Shoot, I was expecting to see a hacked blue light special.

It's 2025. For fucks sake, getting _basic_ USB-C compliance for power is a matter of two fucking SMD resistors. And yet, people are _still_ messing that up.

It seems "vibe electronics" have arrived way earlier than "vibe coding" did.

Yeah. I mean, back in 2019 when Raspberry Pi ran into that very same issue [1], it was excusable, but it's six years later and people still have zero idea what the fuck they are doing?

[1] https://hackaday.com/2019/07/16/exploring-the-raspberry-pi-4...

I wonder if a lawsuit could force them to recall all their lamps and fix the USB port. Then this won't happen again.

At least here in Europe this would actually need to be a USB port which can be charged with any charger and cable.

Compared to plain wires with your intended voltage and your choice of any 2-pin connector, USB-C is not so basic. SMD resistors imply you have a PCB or something to put them on. Which means that your power connector is no longer just a couple pieces of stamped metal and some plastic. It's also a tiny connector with close together pins. For everything else since the introduction of electric lighting, you can just solder two wires on the back and call it a day.

Not that I'm making excuses here - there's some weird stuff going on inside that lamp. There's a PCB for the battery charger, but the USB-C socket isn't on it, it's on a wire pigtail that connects to the board with another connector. And I don't usually see so many removable connectors inside something made so cheaply. They clearly could have done it correctly in this case, but didn't.

> SMD resistors imply you have a PCB or something to put them on. Which means that your power connector is no longer just a couple pieces of stamped metal and some plastic. It's also a tiny connector with close together pins.

So what, there's ready made breakout boards for a few cents that will give you plain old 5V@500mA, and trigger boards for about 1€ at <10 quantity that you can even configure what they should negotiate for.

These things are actually a godsend if you are a QRP ham radio operator and have a USB-C PPS capable power bank. No more heavy AGM batteries - just connect your radio to the trigger board, wire it up for 12V (if the power bank "only" supports PD) or 13.8V if it supports PPS, and off you go.

The OP end result is cooler but I believe they could have sorted out the USB power issue a lot easier with a <$1 (sans tariffs) "USB tricker". Basically USB PD in one end and your choice of output voltage. Then just add a resistor.

Those Lolin32 are really a great form factor and they have the ability to recharge batteries. My only wish is that it should pass the battery voltage level directly to an ADC pin.

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