Hack Correlation

I bought a cheap pass-through socket with 2 USB ports from Pollin . The blue LED is too strong at night so I modified it, see below for the "before" and "after" pictures. Obviously, the unit is photographed with the mains socket missing, that's not how it actually ships. The charger is rated at 1A and in my experience is able to provide more than that. It's actually one of the few non-dedicated chargers in the house that is able charge the iPad without triggering a warning on the screen. Since it doesn't come [directly] from China it's likely built to a decent standard. By the way, the part number was "94-351077", but it's not on stock anymore.  The output is based on a THX202H SMPS regulator with decent specifications. The datasheet for that IC shows a reference circuit for a 5V/1A supply, which is what I guess they used here. The underside shows quite a bit of rework happening: it looks like most of the SMD parts...

I bought this unit as broken for what I thought it was a good price, ~10 EUR while the retail price is around 50 EUR. Since I usually buy stuff that's DOA (Dead on Arrival) the fix turns out to be most of the times a cold soldering joint or a blown capacitor. But first, in case you haven't bought one, here's a Quick review I'm surprised that in this day and age manufacturers still produce units without an auxiliary input, such as the one pictured below. It claims to have 10 Watt output (maximum), infrared remote, can play MP3s from a CD or USB stick and has a radio. Let's review all of that, again: The 10 Watt audio output is produced by a SJ2038 chip which can provided a maximum of 2x3.5W into 4 ohms at 5 volts with a THD of 10%. The speakers are 6 ohms which would mean probably around 2x2.8W output at 10% distortion. Probably less than 4W for decent listening. To be fair, for such a low power the speakers sound decent, much better than all of the c...

A few months ago I bought a cheap Windows 10 tablet for having a dedicated bench instrument that I could connect the oscilloscope, multimeter, logic analyzer to. You can see a bit of it in action in the last photo belonging to this post:  http://hackcorrelation.blogspot.com/2015/10/adding-isolated-data-output-to-mastech.html Quick review The bad This is by no means a powerhorse. It is faster than a Pentium 3 desktop but struggles with Chrome tabs. 2GB of RAM does not help a lot either. Touch input is a bit spotty, sometimes taking one second to respond to a scroll request. On top of that, Windows 10 is not (yet) optimized for touch input which means a lot of the times you'll be hitting the wrong button or link. The other annoying thing is that it cannot charge and use its USB port at the same time - I've already tried a few USB OTG hubs with different settings. Coming out of standby takes between 2 and 5 seconds. The screen is pretty glossy, but at least it...

The apartment I'm renting is missing a key for the living room so I thought a nice experiment would be to try to print one of PLA. I already saw a talk at 32C3 that PLA has sufficient strength to actuate a lock without breaking. I took a photo of the lock and did some basic processing (in MS Paint) to make it easier for the https://keysforge.com website to parse it: I currently cannot get the website to work again but here is the key that was generated from the keyhole shot above: After a miniature print I realized it needed a 2x scaling. Some dremel work a bit later: The underside of the key was removed to make a 'tongue' that is able to catch the latch. Even though the print was done with 80% infill it still broke at the second twist, without ever opening the lock. The next tenant might be surprised to find a piece of PLA as I was surprised to find 5 1-cent coins inside: I already had a similar looking key, but with a mirrored pattern. Some m...