It’s widely known that a smoke detector is a good ionizing radiation source, as they contain a small amount of americium-241, a side product of nuclear reactors. But what about other sources? [Carl Willis] got hold of an old Soviet era smoke detector and decided to tear it down and see what was inside. This, as he found out, isn’t something you should do lightly, as the one he used ended up containing an interesting mix of radioactive materials, including small amounts of plutonium-239, uranium-237, neptunium-237 and a selection of others. In true hacker fashion, he detected these with a gamma ray spectroscope he has in his spare bedroom, shielded from other sources with lead bricks and copper and tin sheets. Continue reading “Soviet Era Smoke Detector Torn Down, Revealing Plutonium”
Everybody should have a few smoke alarms in their house, and everyone should go check the battery in their smoke alarm right now. That said, there are a few downsides to the traditional smoke alarm. They only work where you can hear them, and this problem has been solved over and over again by security companies and Internet of Things things.
Instead of investing in smart smoke alarms, [Johan] decided to build his own IoT smoke alarm. It’s dead simple, costs less than whatever wonder gizmo you can buy at a home improvement store, and reuses your old smoke alarm. In short, it’s everything you need to build an Internet-connected smoke alarm.
Smoke alarms, or at least ionization-based alarms with a tiny amount of radioactive americium, are very simple devices. Inside the alarm, there’s a metal can – an ionization chamber – with two metal plates. When smoke enters this chamber, a few transistors sound the alarm. If you’ve ever taken one apart, you can probably rebuild the circuit from memory.
Because these alarms are so simple, it’s possible to hack in some extra electronics into a design that hasn’t changed in fifty years. For [Johan]’s project, he’s doing just that, tapping into one of the leads on the ionization chamber, measuring the current through the buzzer, and adding a microcontroller with Bluetooth connectivity.
For the microcontroller and wireless solution, [Johan] has settled on TI’s CC2650 LaunchPad. It’s low power, relatively cheap, allows for over the air updates, and has a 12-bit ADC. Once this tiny module is complete, it can be deadbugged into a smoke alarm with relative ease. Any old phone can be used as a bridge between the alarm network and the Internet.
The idea of connecting a smoke alarm to the Internet is nothing new. Security companies have been doing this for years, and there are dozens of these devices available at Lowes or Home Depot. The idea of retrofitting smarts into a smoke alarm is new to us, and makes a lot of sense: smoke detectors are reliable, cheap, and simple. Why not reuse what’s easy and build out from there?
The Internet of Things is getting to be a big business. Google’s Nest brand is part of the trend, and they’re building a product line that fills niches and looks good doing it, including the Nest Protect smoke and CO detector. It’s nice to get texts and emails if your smoke alarm goes off, but if you’d rather not spend $99USD for the privilege, take a look at this $10 DIY smoke alarm interface.
The secret to keeping the cost of [Team SimpleIOThings’] interface at a minimum is leveraging both the dirt-cheap ESP8266 platform and the functionality available on If This Then That. And to keep the circuit as simple and universal as possible, the ESP8266 dev board is interfaced to an existing smoke detector with a simple microphone sensor. From what we can see it’s just a sound level sensor, and that should work fine with the mic close to the smoke detector. But with high noise levels in your house, like those that come with kids and dogs, false alarms might be an issue. In that case, we bet the software could be modified to listen for the Temporal-Three pattern used by most modern smoke detectors. You could probably even add code to send a separate message for a CO detector sounding a Temporal-Four pattern.
Interfacing to a smoke detector is nothing new, as this pre-ESP8266 project proves. But the versatile WiFi SoC makes interfaces like this quick and easy projects.
A faulty wire, a discarded burning cigarette, or a left-on curling iron can trigger sparks of fire to engulf everything nearby until all that’s left is brittle mounds of smoldering ash. Which is why smoke detectors are so important. They are life saving devices that can wake people up sleeping inside, well before the silent, but deadly carbon monoxide starts to kick in. But what happens if no one is home, and the alarm begins to blare? The place burns down into the ground without the owners knowing.
So when [Martin] purchased a battery-powered smoke detector and rigged it up to notify him exactly when the piezo siren is activated, the evolution of the automatic fire alarm continued into the realm of wireless internet-connected things.
His home automation system (a Raspberry Pi running Node-Red) links to a Funky ATTiny84-based sensor and transmits the data wirelessly, redirecting the information to his phone. SMS messages can be sent, as well as emails and pushbullet notifications. Once the piezo siren starts to sing, the system alerts him that smoke has been detected and that he should check on it as soon as possible.
The electronics fit perfectly inside the case waiting for any smoky disturbance in the room to light up. And what makes this project even better, besides the life saving capabilities and the instant push notifications, is that it was hooked up for the cheap. No need to buy a brand-new, expensive Nest protect, when all it takes it a sensor or two and a Raspberry Pi to hack the fire alarm that already sits in the house.
This video coming up after the break shows how simple it is to make. Continue reading “A Cheap DIY Smoke Detector That Can Save Lives”
[Thomas Clauser] had his basement flood last year when a hurricane swept over New England. The problem with flooding or leaking water is that chances are you won’t notice until it’s too late. He decided to protect against this in the future by building his own leaking water detector. It’s a simple device that sits on the floor of his basement and triggers an audio alarm if water begins to cover the floor.
He used an old smoke detector for the build; a nice choice since it’s loud, and designed for long-term battery operation. It also has a button for testing if the detector is working. [Thomas] removed the PCB from the smoke detector case and soldered wires onto the test button contacts. He cut a sponge to squeeze it inside of a PVC pipe connector housing. That sits against the floor, with the wires for the test button contacts placed through the sponge. If water is soaked up by the sponge it completes the circuit and triggers the alarm.
A few other design features really make this a nice setup. He notched out the bottom of the PVC connector so that water can flow freely, and added a switch to one of the probe wires lets him kill the alarm when inspecting the damage.
[Anders] tipped us off about his hack that re-purposes a smoke alarm as a burglar alarm. Unfortunately, he came home in the middle of a burglary but wanted to be ready the next time someone tries to break in. By cleverly patching into the test button on an old smoke detector he created a circuit-trip alarm. One side of each piece of wire is secured to the frame and jam of a window. A paper clip completes the circuit by pinching the two bare conductors. If the window is opened the connection is lost and the alarm sounds.
We see a few problems with this system. First off, never hack your ONLY smoke detector, you are putting lives at risk by doing so. But [Anders] says he’ll have a replacement detector and since these things need to be replace every ten years or so, chances are you can find an old one kicking around. We’d recommend disguising the case so that people aren’t confused about it being a smoke detector. Secondly, he’s mounted the alarm right in the window frame so most likely an invader will just smash the thing to bits.
Anyway, it’s still an interesting reuse of these ubiquitous, and life-saving, devices.