RCWL-0515 Radar Motion Sensor

The RCWL-0515 is a little PCB that can be used as a motion sensor, similar in usage to passive infrared (PIR) sensors. This way you can make a light come on when you enter a room, or sound an alarm when the cat’s waiting at the door.

I bought a couple of these things online for €1.15 each, which makes you wonder quite how they can make something like this so cheaply. It contains one IC labelled “TT1712B”, one transistor labelled “32W” and a bunch of resistors and capacitors. The IC is some custom part for this purpose (I could find no information on it whatsoever), while the transistor is a BFR520[1]https://www.nxp.com/part/BFR520#/, a 9 GHz NPN transistor originally made by NXP but in this case probably by some unknown copycat manufacturer (given that NXP discontinued it in 2016).

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Logitech Skype Phone

Today we’ll look at another piece of obsolete computer hardware: a Skype handset, officially the “Logitech Cordless Internet Handset for Skype”. It’s a cordless phone that you can hook up to your PC so you can place and receive voice calls over Skype while still holding an actual phone-like device in your hand. I don’t think these things are still popular: in offices you generally find “real” phones, whether connected to an actual phone line or through VoIP, while home users either use a headset for teleconferencing software or their mobile for voice calls.

Again, I forgot to take pictures of the complete device, but this is the main PCB found inside. It feels quite cheap, with these radial capacitors soldered horizontally and big blobs of solder on the clock crystal and the battery terminals. It is very well integrated however: all major functionality seems to be packed inside a single IC (the large one in the middle), with two smaller chips implementing the RF interface.

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