home hacks

1867 Articles

Measuring Air Flow With Ultrasonic Sensors

July 26, 2017 by 23 Comments

Measuring air flow in an HVAC duct can be a tricky business. Paddle wheel and turbine flow meters introduce not only resistance but maintenance issue due to accumulated dust and debris. Being able to measure ducted airflow cheaply and non-intrusively, like with this ultrasonic flow meter, could be a big deal for DIY projects and the trades in general.

The principle behind the sensor [ItMightBeWorse] is working on is nothing new. He discovered a paper from 2015 that describes the method that measures the change in time-of-flight of an ultrasonic pulse across a moving stream of air in a duct. It’s another one of those “Why didn’t I think of that?” things that makes perfect sense in theory, but takes some engineering to turn into a functional sensor. [ItMightBeWorse] is using readily available HC-SR04 sensor boards and has already done a proof-of-concept build. He’s getting real numbers back and getting close to a sensor that will go into an HVAC automation project. The video below shows his progress to date and hints at a follow-up video with more results soon.

Here’s wishing [ItMightBeWorse] the best of luck with his build. But if things go sideways, he might look to our post-mortem of a failed magnetic flow meter for inspiration.

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Talking To A Lamp

July 22, 2017 by 10 Comments

Barking commands at furniture seems a bit odd but with voice controlled home automation platforms becoming the norm, you may be spending more time talking to your light fixtures than your kids. In one such project, [Becky Stern] used an Alexa Dot and an ESP8266 respond to voice commands.

The design uses the Alexa Dot to interpret voice commands such as ‘Alexa turn the light ON’. The ESP8266 with a relay feather wing is used to switch the actual lamp ON and OFF. The glue between the two is the fauxmoESP library that allows the ESP8266 to receive commands from the Alexa API.

The best part of the project is the lamp itself which has a wooden base and is perfect for such experiments. [Becky Stern] does a wonderful job at carving out enough space and filling it with the electronics. The additional sanding and wood staining make the project more impressive and worthy of a living room. The idea could be easily extended to other own household items. Check out the video of the project below and for more inspiration, take a look at Theia IoT Light-Switch. Continue reading “Talking To A Lamp” →

Building A Better Baby Bottle Boiler

July 8, 2017 by 34 Comments

[Sebastian Foerster] hasn’t been at his blog in a while. He and his wife just had twins, so he’s been busy standing waiting for formula or milk to warm up. Being a technical kind of guy, he took a look at the tools currently on the market to do this, analyzed them, and decided instead to do it himself.

[Sebastian] looked to his Nespresso Aeroccino – a milk frother designed to give you hot or cold frothy milk for the top of whatever beverage you decide to put it on top of. It made the milk a bit too hot, 60°C, but once it got to the temperature, it would shut off, so if [Sebastian] could get it to shut off at a lower temperature, he had found the solution!

After taking the Aeroccino apart and going over the circuit, it seemed like a simple design relying on a resistor and NTC (negative temperature coefficient) thermistor connected to an ATTiny44 microcontroller. [Sebastian] didn’t want to have to reprogram the ATTiny, so he looked at the resistor and NTC. The resistor and thermistor create a voltage divider and that voltage is read in by the microcontroller through an analog pin. After looking up some info on the thermistor and replacing the resistor with a potentiometer, [Sebastian] could adjust the shut-off temperature while measuring with a thermometer. When he got the temperature he liked, he reads the value of the potentiometer and then replaces it with a couple of resistors in series.

Now [Sebastian] gets the babies’ bottles ready from fridge to temperature in about 25 seconds. He doesn’t have to worry about keeping an eye on the bottles as they heat up. We’re sure that getting two bottles ready in under a minute is much better on the nerves of new parents than waiting around for ten minutes. For more fun with thermistors, check out our article on resistors controlled by the environment or check out this bluetooth bbq thermometer!

An Electric Fence For Snails And Slugs

June 29, 2017 by 72 Comments

Anyone with a garden knows about doing battle with pests. Weeds, bugs, rabbits, birds — all of them try to get a bite out of our flowers and vegetables. Some of the worst are mollusks. Snails and slugs are notorious plant attackers. Tomato plants don’t stand a chance when these beasts come to town. Some folks would reach for the pesticide or even the salt, but [wheldot] had a better idea. He built an electric fence to keep these pests at bay.

Much like the electric fences used for large mammals like horses or cows, this fence is designed to deter, but not kill slugs and snails. The design is incredibly simple – two bare wires are strung around the raised garden about one centimeter apart. The wires are connected to a nine-volt battery. No boost circuit, no transistors, just nine volts across two wires. That’s all it takes to turn a slug away.

[Wheldot] didn’t come up with this hack — it’s been around in various forms for years. The nine-volt battery provides just enough current to annoy the slug or snail. The best part is that when not actively shocking a slug, the only current passing through the circuit is the whatever is passed through the wood.

Reddit user [gnichol1986] measured that at around 180 kΩ through wet wood. That means a typical 400 mAh battery would last around 34 days of continuous rain. Even in the UK it doesn’t rain that much. With a little work insulating the wires from the wood, that could be extended to the full shelf life of the battery.

You know, slugs and critters get into electronics too, so don’t forget a waterproof case to make sure your project stays slug free!

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Amazon Echo Show

June 15, 2017 by 22 Comments

Back in May, Amazon announced the Echo Show, its new version of Alexa with a 7 inch touchscreen. The Echo Show is an interesting device, but will the great unwashed masses pony up $229 to buy the show? That’s $50 more than the original Echo, or $180 more than the Echo Dot. With 5.2 million units sold in 2016, Echo has been a resounding success. This has been in part due to Amazon’s open approach to the API. Anyone can build an Alexa compatible device using a Raspberry Pi. Google has (finally) followed suit with their Home device.

It’s not just the hardware that is accessible. Skills Kit, the programmer interface for extending Echo’s functionality, is also open. At CES this year, Alexa was the belle of the ball. Third party devices are being introduced from all corners, all of them connecting to Amazon’s cloud and responding to the “Alexa” keyword.

The Echo Show takes the family in a new direction. Adding a touch screen gives the user a window on the the world not available with voice interactions. Echo Show also includes a camera, which opens up a whole new set of privacy and security questions. Amazon touts it as a device for viewing security cameras, watching YouTube videos, and making video calls. This puts Echo Show dangerously close to the internet appliance category, essentially a barren wasteland littered with the corpses of previous devices. Does anyone remember when Palm tried this with the 3Com Ergo Audrey? How about the i-Opener? Will Alexa persevere and succeed where others have failed? A lot of it will depend on the third party developers, and how Amazon treats them.

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Ikea Tradfri Hacking

June 14, 2017 by 17 Comments

Smart lighting is all the rage right now. Sure, Phillips Hue is the giant player in the market, but there are plenty of ZigBee, Bluetooth, and WiFi light bulbs out there. Ikea–known for cheap furniture, meatballs, and waffles–is a recent addition to the field with their Tradfri system. Like most things from Ikea, they are effective and inexpensive. [Andreas] takes a Dremel to the controller and shows how to hack the system to use MQTT. You can check out the video below.

Once he had the device opened, the used the German Make magazine article we talked about earlier, to help understand what he had. Armed with the pinout, he was able to solder a wiring harness to the controller. He then connected a WeMos board. A little Arduino code later, and he was controlling the light with MQTT.

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Gas Heater Gets A Battery Backup

June 14, 2017 by 18 Comments

With the availability of cheap modules, it has become easy to hack/make stuff at home and home appliances see the most creative hacks of all. In one such hack, [Vadim] takes the DIY route to adding battery backup to his gas heater.

His existing unit operates on two D-type batteries which need to be replaced once they are depleted. [Vadim] wanted to implement a reversible method since he lives in a rented place. He replaced the original cells with battery adaptors and brought out the connections using two wires. He then proceeded to add two cellphone batteries with a TPS54233 regulator so as to supply the desired voltage to the gas heater. This is interesting since the module used is an official Texas Instruments EVM instead of the traditional eBay purchase.

The batteries in question are charged using modules based on the TP4056 which in turn are fed 5V from power supply modules. The DC voltage is coupled with a LM1117 to provide power to the heater from the mains and the switch over is accomplished using an SPDT relay. The enclosure is a humble box which resembles a plastic food container and is fitted with PG9 cable glands along with a fuse holder to boot. Take a look at the original post for a plethora of images and details of construction.

This an excellent example of a project that came together using available parts to solve a problem without the frills. The DIY fish feeder is another example of a project with functional design and is a great example of DIY.