A cheap motion sensor can do much more than switch on a light

A motion sensor does not have to just turn on a light. How-To Geek writer Adam Davidson lists five rules a plain motion sensor can run, from a dim hallway light at night to a phone alert when mail lands in your mailbox. Motion sensors are cheap and simple to set up, so many people already own one.

Five ways to use one sensor

• Hallway lights that are bright in the evening and very dim at night.
• A morning briefing read aloud by a smart speaker.
• A pantry or cupboard light that comes on by itself.
• A wall tablet that wakes up when you walk near it.
• A mailbox sensor that sends a phone alert.

How the better ideas work

The hallway rule uses the time of day. In the evening, motion turns the lights on at full brightness so you can find the stairs. During the night, the same sensor brings the lights up only dimly, enough to reach the bathroom without waking fully.

The morning briefing starts when a kitchen sensor spots the first motion of the day. The system waits a couple of minutes so everyone can arrive, then a smart speaker reads a spoken summary. In the author's home it covers the weather, school lunches and calendar events. On Mondays it adds the week ahead. On Thursdays and Fridays it reminds the family about trash day. A local AI model writes the text from Home Assistant data, a popular home automation program.

For a wall tablet, an app such as Fully Kiosk Browser can switch the screen on and off. The screen wakes when you approach and turns off after a few minutes without motion. The mailbox idea uses a battery sensor that notices a handful of mail arriving and sends a phone notification or a spoken announcement.

Where motion sensors fall short

A motion sensor detects movement, not presence. If you sit still, it cannot tell you are there. A rule that turns lights off after five minutes without motion can leave you in the dark.

That matters less for a pantry or cupboard. A cooldown timer of a few minutes keeps the light on unless you stay very still for longer than the timer. For lights that should stay on while you are in a room, a presence sensor is a far better choice.

Mailbox notes

In the US, USPS can email you when mail is delivered, but that email is sometimes delayed, so a sensor may beat it. USPS mailbox standards allow devices inside approved mailboxes, as long as they do not interfere with delivery or present a safety risk.