I literally wanted to start this post with “I literally hacked the PiDrive cable…” but I actually have sawn it instead. Duh!
I’m using quite a few Raspberry Pi boards as servers, gateways, etc. and recently started to ‘polish’ their design. Instead of hard drives hanging beside them with a bunch of loose cables I’ve started to buy WD PiDrive Cases and Cables to pack all of them into nice ‘little boxes’.
The PiDrive Cables are really neat: they are designed to be positioned between a Raspberry Pi, its power supply, and an USB hard drive. The cable is designed for USB 3.0 hard drives, but in one case (hah) I wanted to use an external USB 2.0 drive I had lying around. So without further ado I’ve removed the USB 3.0 extension of the connector with a saw. It looks crude but works perfect…
Today my kids impressed me by repurposing/hacking/misusing the toilet-occupied-light to send (morse-like) signals across a railway car. Their fingers were thin enough to press the micro-switches in the doors which normally would signal a locked door (i.e. occupied toilet). Not sure if someone noticed the strangely flashing lights… 😀
A few days ago I was able to get my fingers on, and under, an infrared camera. I had already heard before that the thermal signature of fingerprints is visible for quite some time — but what surprised me was that we were still able to see them for over a minute…
Based on a recent Twitter conversation I had a thought about bank and credit card PIN numbers (sorry for the redundancy): are really all possible PINs issued or are some kept back because bank customers could feel uncomfortable with certain combinations of digits? And would it really matter if some of them were kept back?
It should be obvious that in case of a truly random PIN 4 identical digits are just as likely to occur as any other combination. But certain combinations just do not feel random (I don’t know how to explain it better, I’m not a psychologist).
So I’ve made a small Gedankenexperiment:
- Let’s assume that a bank issues by default a 4-digit PIN. (I know that my bank issues 4-digit PINs by default but they can be changed to any 4- to 6-digit number afterwards.)
- Customers would not accept a PIN with four identical digits (0000, 1111, …, 9999) out of fear that they might be insecure.
- An ATM allows 3 attempts to enter a PIN before locking/withholding a bank/credit card. (This limit is actually the main reason why 4-digit PINs are mostly safe, btw.)
I recently had to revive a (as it at first seemed) dead Li-Ion battery. It was the battery of a newly bought R.O.GNT external speaker which refused to work or even charge. The device was DOA (dead on arrival) but it was so cheap that sending it back would have cost more than I’ve paid for it.
The speaker has an internal Lithium-Ion battery to allow mobile usage. My guess was that this battery slowly discharged while waiting for a buyer and at some point the undervoltage protection kicked in. Normally this protection should prevent a defective cell from being charged. In my case I hoped the cell would still be okay and survive a jump-start. It was successfully done before in other cases. Continue reading
What happens if an obsolete SIM-Card is thrown in acetone?
Well… This was just a brief experiment out of curiosity. To cut it short: the plastic card body is dissolved, what remains are only the microchip and the metal contacts. But see for yourself…
An obsolete T-Mobile SIM card
A SIM card being rinsed in acetone. The plastic has completely dissolved.
A SIM card being rinsed in acetone. Only the microchip and contacts remain.
The remaining metal contacts
In a previous post I had described my efforts to build (or should I say extract) a DCF77 clock radio receiver from an old radio clock. The remaining part of the board has undergone another surgery to take a look at the chip on board (COB) technology (German Wikipedia entry). The process of removing the covering epoxy resin with a scalpel was rather destructing, but I did not want to use aggressive chemicals. As a result, the bonding wires (between the silicon chip and the conductor tracks) were destroyed.
The following video shows the process of removing the epoxy resin using a scalpel and a heat gun (fired up to 200°C). The whole process took about 10 Minutes. The last minute of the video also shows some close-ups done with a cheap webcam, which was modified for magnification.
I also added some close-up pictures of the exposed silicon die, taken with my DSLR and a reverse-mounted lens.
A few weeks ago our old clock radio broke. Out of curiosity I’ve disassembled it: I wanted to remove the DCF77 clock radio signal receiver. Unfortunately, the clock contained a single board, but the receiver part was clearly distinguishable from the rest.
The circuit board of my broken clock radio. The radio signal receiver is marked with a yellow frame.
For fun, I cut out the relevant part of the board and replaced/refreshed the solder joints. I also added four connections for 1.5 Volt (power supply), the clock signal and a power-on line. (At least I think that’s what the last two lines should be).
My low cost self made DCF77 clock signal receiver.
I have not yet managed to get a stable time signal. On my digital storage oscilloscope I get occasional spikes with a distance of one second (what you would expect), but only a few of them and then nothing… The problem is probably the correct initialization of the chip under the black blob (a so called chip-on-board, by the way). Maybe, I also damaged a part of the receiver while cutting out the board, or when resoldering the two joints on the 77.5 kHz antenna.
Update: Well, after playing a bit more with the receiver I’m pretty sure I damaged it while cutting it out. I used common initialization sequences and did not manage to get it work. Too bad…
The Super Talent PICO-C is a really tiny USB flash drive. Ever since I bought mine about a year ago I always wondered how it might look like inside the neat metal housing.
About a month ago, the drive was not accessible anymore. A short search on Google showed that in many cases a bug in the firmware rendered the flash memory inaccessible. There are tools available to revive faulty firmwares, especially for this kind of stick – if at least the controller is still recognized, which was not given in my case. Nevertheless, I tried the tools. As expected, they did not work. Luckily, nothing important was stored on the drive…
Being not that expensive, I did not exchange it (in spite of still having a warranty). Instead, I dissected it. 🙂 Removing the front cover with a screw driver was not complicated.
I first tried to also remove the metal back with a screw driver, but it was firmly glued together. I only managed to break of a piece of the black epoxy (?) housing. Ouch… The solution was to use a hot air gun to melt the glue. The black interior fell out by itself after 10-15 seconds.
Sadly, the black block containing all the logic is rather unspectacular. It does contain a labelling which was only readable after some photoshopping:
BXB08GMBH54UD or BXBO8GMBH54UD
4010 C024L0WAA or CO24LOWAA
MADE IN KOREA
At this point I gave up. Without any further possibilities to dissect the part and without any clues from the caption I put the remains aside. I thought about dissolving it in acetone or a similar solvent but I suspect it would work.
By the way: I bought the same drive again. I hope the new one lasts longer… 😉
Update: I’ve found a nice blog post about the build process of these USB sticks (bunnie’s blog): Where USB Memory Sticks are Born
In 2004, my
girlfriend wife and I went on holidays to Lithuania. Among other places, we visited Klaipeda (Memel) to spend a few days at the Curonian Spit (Kurische Nehrung). It is a famous UNESCO world heritage site. We were lucky, the Baltic Sea was rough and during a morning walk we discovered something glittering in the seaweed: Amber chunks.
In Klaipeda, street vendors offered pretty much any kind of amber “collectibles”. Most of them were counterfeits in egg-shape, with inclusions of wasps or scorpions. But they also had really nice jewelry made of processed amber. A friendly vendor described the manufacturing process: Most amber findings have a milky white or yellow color. They are too shabby for jewelry. These chunks are carefully cooked in sand to gain a clear honey-like color. Back from our vacation, I had to try this out. 🙂
The first picture shows a few pieces of yellow amber, lying on baking paper. They have a diameter of about 3-5 millimeters.After half an hour at about 250°C their color noticeably changed to the typical brown.After an hour their tone was even darker, but did not significantly change anymore.