If someone suggests you spend time working on boring projects, would you take that advice? In this case, I think Kipp Bradford is spot on. We sat down together at the Hackaday Superconference last fall and talked about medical device engineering, the infrastructure in your home, applying Sci-Fi to engineering, and yes, we spoke about boring projects.
Kipp presented a talk on Devices for Controlling Climates at Supercon last year. It could be argued that this is one of those boring topics, but very quickly you begin to grasp how vitally important it is. Think about how many buildings on your street have a heating or cooling system in them. Now zoom out in your mind several times to neighborhood, city, state, and country level. How much impact will a small leap forward have when multiplied up?
The next Hackaday Superconference is just around the corner. Before you join us below for the interview with Kipp, make sure you grab your 2018 Hackaday Superconference ticket to be there for great talks like Kipp’s!
Continue reading “Kipp Bradford On The Importance Of Boring Projects, Medical Tech, And Sci Fi Novels”
We’d wager most readers aren’t intimately acquainted with wax motors. In fact, a good deal of you have probably never heard of them, let alone used one in a project. Which isn’t exactly surprising, as they’re very niche and rarely used outside of HVAC systems and some appliances. But they’re fascinating devices, and once you’ve seen how they work, you might just figure out an application for one.
[AvE] recently did a complete teardown on a typical wax motor, going as far as cutting the thing in half to show the inner workings. Now we’ve seen some readers commenting that everyone’s favorite foul-mouthed destroyer of consumer goods has lost his edge, that his newer videos are more about goofing off than anything. Well we can’t necessarily defend his signature linguistic repertoire, but we can confidently say this video does an excellent job of explaining these little-known gadgets.
The short version is that a wax motor, which is really a linear actuator, operates on the principle that wax expands when it melts. If a solid block of wax is placed in a cylinder, it can push on a piston during the phase change from solid to liquid. As the liquid wax resists compression, the wax motor has an exceptionally high output force for such a small device. The downside is, the stroke length is usually rather short: for the one [AvE] demonstrates, it’s on the order of 2 mm.
By turning heat directly into mechanical energy, wax motors are often used to open valves and vents when they’ve reached a specific temperature. The common automotive engine thermostat is a classic example of a wax motor, and they’re commonly found inside of dishwashers as a way to open the soap dispenser at the proper time during the cycle.
This actually isn’t the first time we’ve featured an in-depth look at wax motors, but [AvE] actually cutting this one in half combined with the fact that the video doesn’t look like it was filmed on a 1980’s camera makes it worth revisiting the subject. Who is going to build a wax motor power device for the Power Harvesting Challenge in the 2018 Hackaday Prize?
Continue reading “Dissecting The Elusive Wax Motor”
Putting everything on the Internet is getting easier and easier, what with the profusion of Internet-ready appliances as well as cheap and plentiful IoT modules to integrate legacy devices. Think IoT light bulbs, refrigerators and dishwashers that can be controlled from a smartphone, and the ubiquitous Sonoff modules. But once these things are on the net, what are they talking about? Are they saying things behind your back? Are they shipping data about your fridge contents off to some foreign land, to be monetized against your will?
Maybe, maybe not, but short of a tinfoil helmet the only way to protect yourself is to build your own system. This IoT control for ceiling fans is a good example, with the added benefit that most wireless ceiling fan remotes are kind of lousy. [microentropie] didn’t like the idea of going the Sonoff route, so his custom controller is based on that IoT workhorse, the ESP8266. There are two versions, one switching the light and fan loads with relays, and one with triacs. The ESP serves up its own web page for control rather than using a cloud service, and is capable of setting up the fan to turn on and off automatically at preset times or temperatures. Everything sits in an unobtrusive box on the ceiling near the fan, but we bet this could be miniaturized enough to fit right inside the fan housing.
If some of [microentropie]’s code looks familiar, it might be because he borrowed it from his IoT rice cooker project.
Infrared remote controls are simple and ubiquitous. Emulating them with the aid of a microcontroller is a common project that hackers use to control equipment as diverse as televisions, cable boxes, and home stereos. Some air conditioners can be a little more complicated, however, but [Ken]’s here to help.
The root of the problem is that the air conditioner remote was using a non-obvious checksum to verify if commands received were valid. To determine the function generating the checksum, [Ken] decided to bust out the tools of differential cryptanalysis. This involves carefully varying the input to a cryptographic function and comparing it to the differences in the output.
With 35 signals collected from the remote, a program was written to find input data that varied by just one bit. The checksum outputs were then compared to eventually put together the checksum function.
[Ken] notes that the function may not be 100% accurate, as they’re only using a limited sample of data in which not all the bytes change significantly. However, it shows that a methodical approach is valuable when approaching such projects.
Thirsty for more checksum-busting action? Check out this hacked weather station.
[Nubmian] wrote in to share his experiments with measuring airflow in an HVAC system. His first video deals with using with ultrasonic sensors. He found an interesting white paper that described measuring airflow with a single-path acoustic transit time flow meter. The question was, could he get the same effects with off-the-shelf components?
[Nubmian] created a rig using a pair of typical ultrasonic distance sensors. He detached the two transducers from the front of the PCB. The transducers were then extended on wires, with the “send” capsules together pointing at the “receive” capsules. [Nubmian] set the transducers up in a PVC pipe and blew air into it with a fan.
Continue reading “Measuring Airflow In An HVAC System”
Everyone is familiar with pinwheels, and few of us haven’t crafted one from a square of paper, a stick, and a pin. Pinwheels are pretty optimized from a design standpoint, and are so cheap and easy to build that putting a pinwheel to work as an HVAC duct flow meter seems like a great idea.
Great in theory, perhaps, but as [ItMightBeWorse] found out, a homemade pinwheel is far from an ideal anemometer. His experiments in air duct flow measurements, which previously delved into ultrasonic flow measurement, led him to try mechanical means. That calls for some kind of turbine producing a signal proportional to air flow, but a first attempt at using a computer fan with brushless DC motor failed when a gentle airflow couldn’t overcome the drag introduced by the rotor magnets. But a simple pinwheel, custom cut from patterns scaled down from a toy, proved to be just the thing. A reflective optosensor counts revolutions as the turbine spins in an HVAC duct, and with a little calibration the rig produces good results. The limitations are obvious: duct turbulence, flimsy construction, and poor bearings. But for a quick and dirty measurement, it’s not bad.
Looking for an outdoor anemometer rather than an HVAC flow meter? We’ve got one made from an old electric motor, or a crazy-accurate ultrasonic unit.
Continue reading “Custom Cut Pinwheel Makes A Useful HVAC Duct Flow Meter”
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.
Continue reading “Measuring Air Flow With Ultrasonic Sensors”