In mid-2015, as some of you may recall, I tore down an AT&T 3G Microcell that had failed for unknown reasons. Its replacement, which I'd previously been using at my now-sold California residence, worked fine here in Colorado, too ... until the other day.

I began noticing that my smartphone would randomly drop the connection to the femtocell, relying instead on the weaker signal coming from a regional cell tower, even though illuminated front panel LEDs implied that the femtocell was still working fine. Later, the smartphone-to-femtocell connection would be back again. And after a few days of this up-and-down behaviour, I noticed that the smartphone would no longer connect to the AT&T 3G Microcell at all; looking at it, I saw that the LEDs were all extinguished.

Given the microcell's prior erratic behaviour, I assumed I had another deceased unit on my hands. Before tossing it in the trash, however, I had a hunch; maybe its "wall wart" had failed instead. Disconnecting the power supply from the femtocell and instead hooking it up to a multimeter confirmed that it was no longer outputting any DC voltage. I'm guessing that the power supply initially was periodically outputting only enough current to power the front panel LEDs, but insufficient to fully fuel the entirety of the unit's circuitry, therefore explaining the random disconnects I was experiencing.

Fortunately, after tearing down the prior femtocell and then discarding it, I hadn't also discarded its wall wart. Instead, I'd added it to the collection I'd been assembling for years; leftover power supplies from failed hardware of the past. As you likely already realise, my likelihood of being able to re-use a particular wall wart with a different piece of gear was low at best; output voltage and current requirements vary widely, along with plug dimensions and polarities. But I've always found it difficult to toss something that I knew was still working just fine.

In this particular case, however, my job was made much easier by the exact match between old and new hardware to be powered. And indeed, when I connected the older wall wart to the newer microcell and then plugged the power supply into a wall outlet, the AT&T 3G Microcell's resurrection was a complete success. I don't know about you, but a no-cost spare part beats a several hundred dollar full replacement any day, in my book.

So the next time your residence co-inhabitants (children, parents, roommates, significant other, spouse, etc.) grumble about all that "junk" you keep stockpiling, feel free to pass along my happy tale. I can't promise it'll help, but hey, it can't hurt!