I just noticed this device in my apartment and am wondering if anyone with some electronics knowledge can tell me what it is.
3 Answers
It looks like a EN1723 - Dual Input Temperature Transmitter
https://www.inovonics.com/products/dual-input-temperature-transmitter-en1723/
It is an Inovonics EN1723 dual input temperature sensor. The green two pin connector would be attached to an external thermistor, but is not used in this case, and the internal thermistor is used. It connects wirelessly in the 902-928 Mhz range to a remote receiver. It's used for logging temperature in the apartment. The owner of the building is monitoring temperatures in the apartments, which will set off an alarm, if the temp goes out of a pre-defined range.
It's hard to say.
There are no external connections, so it communicates wirelessly. This is supported by the fact that there are two chips and two crystals — a microcontroller and and an RF chip.
However, there are no obvious sensors or other transducers, so it's difficult to guess what kind of information it might be processing.
Since it is next to a door, it might be part of a security system.