PiRoar is a standalone motion alarm the size of an apple. When someone walks in, it hits them with a 100+ dB siren and a blinding strobe. Twist the top to arm it. Leave it for years. You pay once, at a low price, with no app, no monitoring plan and no monthly fees.
Use cases
Most break-ins happen where nobody is watching and nobody is listening. PiRoar makes sure the intruder is the one who gets the surprise. No mains power, no internet and no installation needed.
Leave it on the dashboard, console or back seat. The moment a door or window opens and someone leans in, PiRoar roars from inside the cabin and flashes through the glass. Thieves don't hang around to find your stuff.
Tip: use lithium AA cells. Park in the shade where you can, as cabins get very hot in summer sun.
Unheated, off-grid and empty for months. PiRoar runs on batteries through the winter, ignores the cold with lithium AA, and is still ready on the day someone forces the door.
Built for: −20 °C to +50 °C, no power, no cell signal.
Away for the winter, between tenants, waiting on a sale or settling an estate? Put a PiRoar by the entrance. If someone gets in, the whole building and the street will hear about it.
Tip: plug it into a USB charger and the batteries become a silent backup.
Cabins, cuddies and consoles at the dock or on a mooring. PiRoar needs no shore power and no connection. It sits quietly below deck until someone climbs aboard who shouldn't.
Tip: run it from the boat's USB-C outlet with AA backup.
In storage for the off-season, or parked at a trailhead for the day. Arm it with a twist when you lock up. It runs on its own batteries, so it doesn't drain the house battery.
Tip: one unit by the entry door covers a typical camper.
Tool sheds, storage units, workshops, small offices and warehouses after hours. Anywhere wiring in a full alarm system would cost more than what it protects.
Tip: two keyholes on the back for a screw mount.
How it works
There's no app to pair, no account and no code to remember. The top cap is the switch: twist it to ON and the window opens over the sensor. Twist it to OFF and the window closes.
Stand it on a shelf or table facing the door, or fix it with adhesive tape. It looks straight out into the room.
A short chirp confirms it's on, and a blink shows the battery state. You have 60 seconds to leave.
When it detects motion, PiRoar chirps for 15 seconds. Disarm with a quick twist code: OFF, ON, OFF.
If motion continues, the siren screams for 3 minutes and the strobe fires. Then it re-arms itself once the room is quiet.
Longevity
Most battery gadgets slowly drain themselves just by waiting. PiRoar doesn't. While armed, its processor is completely powered off. Only the motion sensor and a tiny wake-up circuit stay alive, drawing less than 10 microamps.
Then 10 full alarm events remaining
Design targets for the production unit, at 20 °C (alkaline) and down to −20 °C (lithium). Actual results depend on cells, temperature and how often it is triggered.
Power options
No special battery packs, no proprietary chargers. Use what you already have, alone or together.
Available in every corner store in the world. Swap them in seconds through the door underneath, no tools needed.
Plug it into any 5 V USB-C phone charger. The batteries stay in as a backup and don't drain.
In a car, boat or tent, connect a power bank to stretch the run time far beyond the batteries alone.
Pay once
Most alarm systems are cheap to start and expensive to keep. PiRoar is the opposite: you buy it once, and the only running cost is a set of AA batteries every couple of years. It's affordable enough to put one in the car, one at the cottage and one on the boat.
Paid for every month, for as long as you keep it
One purchase. Yours outright.
Pricing will be announced at launch. Waitlist members get early-bird pricing.
Built to scare, designed to behave
An alarm only works if it goes off when it should, and only then. PiRoar keeps its logic simple and its manners good.
A piezo siren in the warble range people find hardest to ignore, aimed up through the dome so it fills the room.
Two camera-flash LEDs fire at the intruder, a shock for anyone looking at it. The flashes are visible through windows, and stay at 2 Hz or below.
A digital PIR sensor sees about 94° across and 5 m or more, looking straight through the front window.
One flicker doesn't set it off. It needs motion again during the 15-second entry warning before it sounds the siren.
It re-arms only after 5 quiet minutes and sounds at most 2 alarms per arming. Repeated triggers drop to a short flash only.
Come back and twist it: it blinks once for every alarm that happened while you were away.
OFF alone doesn't disarm during an entry warning. Only the OFF, ON, OFF code does, which a stranger won't know.
A recessed slide switch, reached with a pen tip, cuts the electronics in hardware. It's a last resort that always works.
Nothing to hack remotely, nothing to renew. It works the same in ten years as it does on day one.
Specifications
Design targets for PiRoar V1. Final figures will be published once production units are tested.
| Size | Ø 82 mm × 48 mm; orange twist cap, black base |
|---|---|
| Siren | ≥ 100 dB(A) at 1 m, 2.5–4.5 kHz warble |
| Strobe | 2 × white flash LEDs, short pulses at ≤ 2 Hz |
| Motion sensor | Digital PIR, about 94° horizontal × 82° vertical, 5 m+ range |
| Arm / disarm | Twist the cap (60°): magnet and Hall sensor, twist code to disarm |
| Batteries | 3 × AA (lithium recommended for cold), tool-free door |
| External power | USB-C 5 V: power adapter or power bank, seamless switch-over to AA |
| Standby current | ≤ 10 µA while armed or off |
| Endurance | 2 years (alkaline) / 3 years (lithium) armed, then 10 + 3 alarm events |
| Operating temperature | −20 °C to +50 °C, indoor / sheltered |
| Mounting | Free-standing, adhesive tape, or 2 keyholes for screws |
| Processor | Raspberry Pi RP2350, powered only when needed |
| Connectivity | None in V1 (by design). Wi-Fi version planned |
| Running costs | None: no subscription, activation or service fees. A set of AA cells every 2–3 years |
FAQ
No. PiRoar V1 is completely standalone: no account, no app, no monthly fee and nothing to connect. That's also why it lasts so long on batteries. A connected version that can send notifications to your phone is planned.
The design target is 2 years armed on alkaline AA cells or 3 years on lithium AA, and it can still sound 10 full alarms after that. The processor is completely switched off until motion wakes it, so waiting costs almost nothing. Every time you arm it, it checks the batteries under load and warns you when they're getting low.
Yes, that's one of its jobs. Put it where it can see the doors, such as the console, a seat or the rear shelf. Use lithium AA cells. A parked car can get far hotter than +50 °C in direct summer sun, so park in the shade, or keep the unit out of direct sunlight, under a seat cover or a sunshade.
Any USB-C power bank that keeps its output on at very low current. Many banks switch off when the device draws almost nothing, as PiRoar does when armed. Look for an "always-on", "low-current" or "trickle" mode. With AA cells fitted, PiRoar keeps working even if the bank switches off.
Nothing visible happens. With AA cells fitted, PiRoar switches to them instantly, with no reset, no gap and no false alarm, even in the middle of an alarm.
During the 15-second entry warning, twist the cap OFF, ON, OFF within 3 seconds. If something ever goes wrong, a recessed emergency switch at the back (reach it with a pen tip) cuts power to the electronics in hardware.
A PIR sensor sees warm moving bodies, so a cat or dog walking through the room can trigger it. PiRoar is meant for places that should be empty. Point it at the entrance, and use the entry warning to disarm when you come in.
V1 is for indoor and sheltered spaces: inside a cabin, car, boat or RV, not exposed to rain or spray.
We'll announce the price at launch. The goal is a low, one-time price: low enough that you can buy one for the car, one for the cottage and one for the boat. There are no subscriptions, activation fees or paid features, and no ongoing costs other than AA batteries every couple of years. Waitlist members get early-bird pricing.
PiRoar is in development and prototypes are being built now. The first units ship in early 2027, in a limited first batch. Waitlist members get the first chance to order from it, at early-bird pricing.
Early access
The first batch is limited. Join the waitlist for first access to it, early-bird pricing and the chance to test a pre-production unit. A few emails before launch, no spam.