Recently bought a house that's about 40 years old. The previous owner was clearly very fond of doing the wiring himself and has left me some idiosyncrasies to work out. One is this box in one of my bedrooms. No idea what it is, or is supposed to do but I see extra wires coming straight out of the sheet rock on the bottom of it. Can anyone tell me what it is?
Conveniently, it still had the UPC barcode label and you captured it quite clearly in the picture.
Description Brinks Home Security System AC Power Adaptor Size/Weight 5x3x3, 12 ounces Issuing Country United States
Universal UB1640W 16.5 VAC 40 VA Plug-In Wall Transformer
AC Output Voltage 16.5 V Current Capacity 2400 mA Center/Tip Polarity AC Plug Input Voltage 110~120 VAC
So, it appears to be a low voltage 16.5 VAC transformer that is (or at least was) a part of a home security system. Looks like the screw on top is meant to screw into the outlet for semi-permanent installation.
Of course, it's possible that it was re-purposed for something else like low voltage lighting, a doorbell, or who knows what it may be used for.
This is a transformer or DC power supply. Odds are that this was installed years ago by the telephone company to power land-line telephones with light-up dials ("princess" phones). This was well before LED lighting that pulled small-enough power to run right off of the power from the central office.