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NVQ Key Finder Locator
The NVQ Model NF08 is an inexpensive ($10) key tag locator that is iOS/Airtag compatible and can be found using the "Find Me" app. The ability to do world-wide communication with this device with no subscription charges intrigued me and I bought a few to tinker with them. Since it is possible to activate the sounder from the iPhone app, I could have it actuate something remotely (send a single bit command).
Left: cover. Middle: frame. Right: Board inside lower cover.
Underside of above board.
Red:Battery+, Black: Battery- and system return,
White: Piezo sounder contact.
I was able to power the unit from a bench
top supply and it worked normally down to about 2.4V.
Below that, it would continue to draw current and not go to
sleep if the sounder was activated.
Normal current is about 4mA peak for about 2msec every two seconds. When the sounder is active, supply current goes to 7mA continuous.
Normal current is about 4mA peak for about 2msec every two seconds. When the sounder is active, supply current goes to 7mA continuous.
Scope on White terminal with respect to Black during a
sound commanded on. 4kHz at 8V peak.
On the Find Me app, this device shows a
battery status bar. It occurred to me that I could use
this for the device to send data back to me. I could lower
the supply voltage to it and that would be one way to send me
one or two bits of data back. My initial work with this
was unsuccessful and it would only show me a full battery in the
app even when down to 2.4V supply. I assumed from that the
battery indicator was bogus, but in August 2024 the tracker I
was experimenting with showed a low battery. More on this
in the future.
Project Log
- April 2024. Started project with several
units.
- August 2024. One unit showing low
battery. It went back to full indication after a
day.
- December 2024. Several units starting
consistently showing low battery. As a test, I
removed the battery and reinserted the same one.
They then started to show full battery again. This
corroborates my suspicion that it simply shows low battery
after a certain amount of time and not based on battery
voltage. The lowest battery was around 2.78V (3.2V
new).
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(c) 2024 Edward Cheung, all rights reserved.