The Nordic Semiconductor nRF24L01 is the older sibling of the nRF24L01+ and is not recommended for new designs anymore. Sometimes, if you’re looking for a cheaper bargain, the older chip may the way to go. [necromant] recently got hold of a bunch of cheap nrf24l01 modules. How cheap ? Does $0.55 sound cheap enough?
Someone back east worked out how to cost-optimize cheap modules and make them even cheaper. At that price, the modules would have severe performance limitations, if they worked at all. [necromant] decided to take a look under the hood. First off, there’s no QFN package on the modules. Instead they contain a COB (chip on board) embedded in black epoxy. [necromant] guesses it’s most likely one of those fake ASICs under the epoxy with more power consumption and less sensitivity. But there’s a step further you can go in making it cheaper. He compared the modules to the reference schematics, and found several key components missing. A critical current set resistor is missing (unless it’s hiding under the epoxy). And many of the components on the transmit side are missing – which means signal power would be nowhere near close to the original modules.
The big question is if they work or not ? In one test, the radio did not work at all. In a different setup, it worked, albeit with very low signal quality. If you are in Moscow, and have access to 2.4Ghz RF analysis tools, [necromant] would like to hear from you, so he can look at the guts of these modules.
Thanks to [Andrew] for sending in this tip.
[zeptobars], the folks behind all the decapping hard work and amazing die shots are at it again. This time they decided to look under the hood of two identical looking Nordic nRF24L01+ chips.
The nRF24L01+ is a highly integrated, ultra low power (ULP) 2Mbps RF transceiver IC for the 2.4GHz ISM (Industrial, Scientific and Medical) band. Popular, widely used and inexpensive – and the counterfeit foundries are drawn to it like honey bees to nectar. But to replicate and make it cheaper than the original, one needs to cut several corners. In this case, the fakes use 350nm technology, compared to 250nm in the original and have a larger die size too.
These differences mean the fakes likely have higher power usage and lower sensitivities, even though they are functionally identical. The foundry could have marked these devices as Si24R1, which is compatible with the nRF24L01 and no one would have been wiser. But the lure of higher profits was obviously too tempting. A look through Hackaday archives will dig up several posts about the work done by [zeptobars] in identifying fake semiconductors.
[Angus Gratton] recently cracked open a pair of USB to Ethernet converters to see what’s inside. One was an Apple branded device, the other a no-name from eBay. The former rings in at $30, with the latter just $4. This type of comparison is one of our favorites. It’s especially interesting with Apple products as they are known for solid hardware choices and the knock-offs are equally infamous for shoddy imitations.
From the outside both devices look about the same. The internal differences start right away with a whole-board metal shield on the Apple dongle and none on the off-brand. But the hardware inside is actually quite similar. There’s an RJ-45 jack on the left, followed by the Ethernet isolation chip next to it. From there we start to see differences. The off-brand had a blank chip where Apple’s ASIX AX88772ALF USB to Ethernet bridge controller is located. There is also a difference with the clock; Apple is using two crystals with the other using just one.
Check out how the light hits this piece of artwork. It’s a very convincing piece of stained glass… except it’s fake. [Sdtacoma] figured out a way to mimic stained glass using a single pane. The inspiration for the project came after seeing a real stained glass panel featuring Iron Man which was available on Etsy for $4500.
Due to popular demand [Sdtacoma] posted an album of the technique he used. Starting with some art found online he made it black and white, blew it up to size (this thing’s about five feet tall) and used posterizer to print it out using multiple sheets of paper.
The frame and pane were found at a recycled building goods store. After cleaning it up he used the paper template to lay out the dividing lines between different colored sections using Liquid Lead. The product had dimension to it (kind of like puffy paint for fabrics) which looks like the lead tracks between panes of stained glass. Once dry the color was added using an eye dropper to apply glass paint.
[Giorgos Lazaridis] needed an AC adaptor for his Canon PowerShot camera. He hit eBay and was excited to find this branded adaptor for just five bucks! It works and, even though it would sometimes reboot his camera if the cord was twisted around in the jack, he was satisfied that it did what it was supposed to.
That is, until one day he observed some very peculiar behavior while taking pictures of a PIC circuit he was prototyping. When holding the camera and putting his other hand near the breadboard one of the status LEDs in his circuit began flashing sporadically. If he was using the camera with batteries instead of the adapter this didn’t happen.
His first instinct was to hook up the adapter to his oscilloscope and see what is happening on the power bus. The signal is incredibly noisy. Shockingly so. [Giorgos] cracked open the case to see what is going on with the power supply circuit inside. You simply must view the video after the break to see the horror-show he found. The board is poorly soldered, components are not properly seated in their footprints, and our favorite is when [Giorgos] points out a squiggly trace which takes the place of the smoothing inductors.
Have you documented your own fake electronic hardware finds? We’d love to hear about them. Continue reading “Exposing some fake electronics with too-good-to-be-true prices”
Instructables user [GuokrDIY] has provided a translation of a detailed guide on making one of our favorite Escher inspired illusions. Unlike the previous speculated solutions to Escher’s waterfall this one manages to keep the water path coherent up until the top level. The trick of the whole setup is very carefully controlling perspective to overlap the water source and outlet. We say water but for some reason the builder is actually using “toilet detergents” as the liquid… At any rate, the liquid is allowed to flow downhill until it reaches the fourth corner, which does not exist. The liquid actually falls off the end of the table (out of sight) and into a basin. A carefully timed pump in the basin pushes liquid up to the top of the waterfall through one of the model’s pillars, where it then cascades over the wheel.
Using sketchup to model the various structural components of the waterfall the design is fashioned out of PVC and ABS plastic, then skinned with mapped textures to ensure that everything looks coherent. The visual details are fine tuned by viewing the whole setup through a camcorder. The hardest part of the illusion seems to be modulating power to the pump in order to time it with the liquid’s flow.
We just hope that thing about toilet detergent was a mistranslation or some kind of sarcasm from the original Chinese article. Check out the model in action after the jump!
Continue reading “Build a real-life Escher’s Waterfall”
Study the image above closely. You’ll notice that physically it is an impossible object, yet this is a screenshot of full-motion video. The clip after the break shows a gentleman pouring water into the waterfall where the wheel is located. The liquid flows in a direction that appears to be uphill, then falls onto the waterwheel where it was originally poured. Ladies and Gentleman, we have the solution to the world’s energy crisis. Nope, we have a hoax and the real question is how was it done?
[David Goldman] has come up with quite the explanation. He watched the video very closely and the put together a three-dimensional diagram showing how he would build the apparatus. If you saw the movie Inception (we highly recommend you do) you will remember the infinite stair puzzle that is exposed as an optical illusion. [David’s] proposed method for debunking this hoax uses a similar build that comes in four different, precisely placed elements.
We’ve got to hand it to him. That’s a brilliant theory! Of course the first commenter on the post linked above calls this out as CGI and we’re inclined to go with that answer but that’s much less fun.
Continue reading “How Escher’s impossible waterfall was faked”