Sense All the Things with a Synthetic Sensor

What will it take to make your house smarter than you? Judging from the price of smart appliances we see in the home centers these days, it’ll take buckets of cash. But what if you could make your home smarter — or at least more observant — with a few cheap, general purpose “supersensors” that watch your every move?

Sounds creepy, right? That’s what [Gierad Laput] and his team at the Carnegie Mellon Human-Computer Interaction Institute thought when they designed their broadband “synthetic sensor,” and it’s why they purposely omitted a camera from their design. But just about every other sensor under the sun is on the tiny board: an IR array, visible light sensors, a magnetometer, temperature, humidity, and pressure sensors, a microphone, PIR, and even an EMI detector. Of course there’s also a WiFi module, but it appears that it’s only for connectivity and not used for sensing, although it clearly could be. All the raw data is synthesized into a total picture of the goings on in within the platform’s range using a combination of machine learning and user training.

The video after the break shows the sensor detecting typical household events from a central location. It’s a powerful idea and we look forward to seeing how it moves from prototype to product. And if the astute reader recognizes [Gierad]’s name, it might be from his past appearance on these pages for 3D-printed hair.

Continue reading “Sense All the Things with a Synthetic Sensor”

Stairwell Lights Keep Toddler with Night-Blindness Safe

A devastating diagnosis for a young child is every parent’s worst nightmare. All too often there’s nothing that can be done, but occasionally there’s a window of opportunity to make things better for the child, even if we can’t offer a cure. In that case even a simple hack, like a rapid response stairwell light to help deal with night-blindness, can make a real difference.

[Becca] isn’t yet a year old, but she and her parents carry a heavy burden. She was born with Usher Syndrome, an extremely rare genetic disease that affects hearing and vision to different degrees. In [Becca]’s case, she was born profoundly deaf and will likely lose her sight by the time she’s 10 or so. Her dad [Jake] realized that the soon-to-be-toddler was at risk due to a dark stairwell and the night-blindness that accompanies Usher, so he came up with a simple tech solution to the problem.

He chose Philips Hue LED light strips to run up the stringer of the stairs controlled by a Raspberry Pi. Originally he planned to use IFTTT for the job but the latency resulted in the light not switching on fast enough. He ended up using a simple PIR motion sensor which the Pi monitors and then uses the Hue API to control the light. This will no doubt give him a platform for future capabilities to help [Becca].

We’ve covered a few builds where parents have hacked solutions for their kids, like this custom media center for the builder’s autistic son. We suspect [Jake] has a few more tricks up his sleeve to help [Becca], and we’re looking forward to seeing how she does.

Evaluating the Unusual and Innovative Perf+ Protoboard

Back in 2015 [Ben Wang] attempted to re-invent the protoboard with the Perf+. Not long afterward, some improvements (more convenient hole size and better solder mask among others) yielded an updated version which I purchased. It’s an interesting concept and after making my first board with it here are my thoughts on what it does well, what it’s like to use, and what place it might have in a workshop.

Perf+ Overview

One side of a Perf+ 2 board. Each hole can selectively connect to bus next to it with a solder bridge. The bus strips are horizontal on the back side.
One side of a Perf+ board. Each hole can selectively connect to the bus next to it with a solder bridge. These bus strips are vertical. The ones on the back are horizontal.

The Perf+ is two-sided perfboard with a twist. In the image to the left, each column of individual holes has a bus running alongside. Each hole can selectively connect to its adjacent bus via a solder bridge. These bus traces are independent of each other and run vertically on the side shown, and horizontally on the back.

Each individual hole is therefore isolated by default but can be connected to one, both, or neither of the bus traces on either side of the board. Since these traces run vertically on one side and horizontally on the other, any hole on the board can be connected to any other hole on the board with as few as two solder bridges and without a single jumper wire.

It’s an innovative idea, but is it a reasonable replacement for perfboard or busboard? I found out by using it to assemble a simple prototype.

Continue reading “Evaluating the Unusual and Innovative Perf+ Protoboard”

Lighting The Great Indoors With A Solar Security Light

Look at any list of things to do to make your house less attractive to the criminal element and you’ll likely find “add motion sensing lights” among the pro tips. But what if you don’t want to light up the night? What if you want to use a motion sensor to provide a little light for navigating inside a dark garage? And what if the fixture you’ve chosen is a solar fixture that won’t quite cooperate? If you’re like [r1ckatkinson], you do a teardown and hack the fixture to do your bidding.

[r1ckatkinson]’s fixture was an inexpensive Maplin solar unit with PIR motion sensing, with the solar panel able to be mounted remotely. This was perfect for the application, since the panel could go outside to power the unit, with the lamp and PIR sensor inside. Unfortunately, the solar cell is also the photosensor that tells the unit not to turn on during the day. Armed with scratch pad and pencil, [r1ckatkinson] traced the circuit and located the offending part – a pull-down resistor. A simple resistor-ectomy later and he’s got a solar-powered light working just the way he likes it.

A simple hack, but effective. Seeing off-the-shelf gear modified is always a treat. Of course there’s something to be said for the more home-brew approach to security lighting, too.

A Motion Activated AC Switching Circuit using Mostly Discrete Components

AC motion switch

If you’ve ever dealt with a brightly lit Christmas tree, you might understand the frustration of having to crawl underneath the tree to turn the lights on and off. [brmarcum] feel’s your pain. He’s developed his own motion activated AC switching circuit to turn the lights on and off automatically. A motion sensor ensures that the lights are only on when there are people around to actually see the lights. The circuit also has an adjustable timer so [brmarcum] can change the length of time that the lights stay on.

The project is split into several different pieces. This makes the building and debugging of the circuit easier. The mains power is first run through a transformer to lower the voltage by a factor of 10. What remains is then filtered and regulated to 9VDC. [brmarcum] is using a Parallax PIR sensor which requires 4.5V. Therefore, the 9V signal is then lowered once more using a voltage divider circuit.

When the PIR sensor is triggered, it activates the timer circuit. The timer circuit is driven by a 555 timer. The circuit itself was originally borrowed from a classic Forrest Mims book, though it was slightly modified to accommodate the PIR sensor. The original push-button trigger was removed and replaced with the signal from the PIR sensor. The only problem is that the circuit was expecting a low signal as the trigger and the PIR sensor outputs a high signal. [brmarcum] resolved this problem with an NPN BJT to invert the signal. Once the timer is triggered, it flips on a relay that allows the mains electricity to flow through to the lights.

[brmarcum] soldered the entire circuit onto a piece of protoboard. The final product was then mounted securely inside of an insulated plastic case. This allows him to mount the circuit safely underneath the Christmas tree skirt. The PIR sensor is kept external to the enclosure and wired up into the tree itself. This allows the sensor to still detect motion in the room while the rest of the circuit is hidden away.

[via Reddit]

Making the electronics for a Doppler motion sensor

There are many different sensors that can be used to detect motion in a given environment. Passive InfraRed (PIR) sensors are the most used today, as they work by detecting moving heat signatures. However, they are less reliable in the hotter days and obviously only work for animals and humans.

Sensors like the one shown in the above picture started to appear on the internet, they use the doppler effect to detect motion. I (limpkin) designed the electronics you need to add in order to get them to work.

Here is a simple explanation of the doppler effect: if you send an RF signal at a given frequency to a moving target, the reflected signal’s frequency will be shifted. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession. Continue reading “Making the electronics for a Doppler motion sensor”

SenseLamp automates rooms by replacing light fixtures


Would you believe that this beautiful light fixture is actually a hacked together home automation project? Okay, so this wire mess is the second of three versions that [Christian] built. It replaces a light fixture in the room, but if you look closely you’ll see that there is a compact fluorescent bulb included in the build. The laser-cut frame acts as a bit of a lamp shade, while providing a place to mount the rest of the hardware.

The final version cleans things up a bit, and adds a footprint for the PIR motion sensor that he forgot to design into this version. The idea is that each lamp monitors motion in the room, switching the light on and off again as necessary. A light-dependent resistor ensures that the bulb is only powered up if the room is dark so as not to waste electricity during the day.

The build includes a sensor package that reports back temperature and humidity data. Communications are provided by a WR703N router rolled into each of the four units installed in his house. With this kind of hardware at his disposal it should be a snap to control every IR remote control device in his house via the network by adding an IR LED and some code to the lamps.