Smoke alarms, or at least ionization-based alarms with a tiny amount of radioactive americium, are very simple devices ... alarm with relative ease. Any old phone can be used as a bridge between ...

It uses a very small photodiode ... enough to detect the small amounts of gamma radiation produced from a smoke alarm americium source, and also registers [Alan]’s other more powerful ...

I couldn’t give you an exact number, but it’s it’s very common for people to have either improperly installed smoke detectors, expired batteries, old smoke detectors,” Schnaper said.