How exactly does salt help? The very fine salt coating deposited on the fibers of a mask’s filtration layer first dissolves on contact with airborne pathogens, then undergoes evaporation-induced recrystallization. Pathogens caught in the filter are therefore exposed to an increasingly-high concentration saline solution and are then physically damaged. There is a bit of a trick to getting the salt deposited evenly on the polypropylene filter fibers, since the synthetic fibers are naturally hydrophobic, but a wetting process takes care of that.
The salt coating on the fibers is very fine, doesn’t affect breathability of the mask, and has been shown to be effective even in harsh environments. The research paper states that “salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%).”
There is nary a microcontroller to be found on this circuit sculpture, which uses a pair of astable multivibrator(s) to light two sets of LEDs that represent air being inhaled and exhaled. We like that [bornach] used two sized of exhale LEDs to represent droplets and aerosols in this beautiful circuit sculpture, and we love that most of the components were scavenged from old electronics and older projects.
If there’s any holiday that is worth adjusting for strange times, it’s gotta be Halloween. Are you inclined to leave a bowl of candy on the porch to avoid the doorbell? If so, this is the perfect year to finally figure out some sort of metering apparatus so that greedy preteens are less likely to steal your stash in one sweep. There’s still time to make something fun like [Brankly]’s automatic candy dispenser, which we think ought to stick around for many years to come. Video is posted after the break.
Underneath that skeleton’s jack-o-lantern head is the heart of this build — an orange 5-gallon bucket that matches it perfectly. Simply step on the giant lighted arcade button, and the equally giant NEMA-23 stepper motor moves a 3D-printed turntable inside the bucket with the help of an Arduino Nano. This moves the candy toward the 3D-printed ramp and out the mouth of the jack-o-lantern, where it lands in a bowl that lights up when it hits the bottom thanks to a relay and a second Nano.
[Brankly] made clever use of IR break-beam switches, which sit underneath the two square holes in the ramp. Once candy passes over one of them, the turntable stops and rotates backward to move the candy where it can’t be reached.
Frankly, we love that [Brankly] reused the sound effects module that came with the jack-o-lantern. This build is totally open, and [Brankly] is even giving away 40 PCBs if you want to make your own. For now, you can check out the code and start printing the STLs.
Back in April we challenged hackers to make the best of a tough situation by spending their time in isolation building with what they had laying around the shop. The pandemic might have forced us to stay in our homes and brought global shipping to a near standstill, but judging by the nearly 300 projects that were ultimately entered into the Making Tech At Home Contest, it certainly didn’t stifle the creativity of the incredible Hackaday community.
While it’s never easy selecting the winners, we think you’ll agree that the Inverse Thermal Camera is really something special. Combining a surplus thermal printer, STM32F103 Blue Pill, and OV7670 camera module inside an enclosure made from scraps of copper clad PCB, the gadget prints out the captured images on a roll of receipt paper like some kind of post-apocalyptic lo-fi Polaroid.
The HexMatrix Clock also exemplified the theme of working with what you have, as the electronics were nothing more exotic than a string of WS2811 LEDs and either an Arduino or ESP8266 to drive them. With the LEDs mounted into a 3D printed frame and diffuser, this unique display has an almost alien beauty about it. If you like that concept and have a few more RGB LEDs laying around, then you’ll love the Hive Lamp which took a very similar idea and stretched it out into the third dimension to create a standing technicolor light source that wouldn’t be out of place on a starship.
Each of these three top projects will receive a collection of parts and tools courtesy of Digi-Key valued at $500.
Out friends at Digi-Key were also kind enough to provide smaller grab bags of electronic goodies to the creators of the following 30 projects to help them keep hacking in these trying times:
The Making Tech At Home Contest might be over, but unfortunately, it looks like COVID-19 will be hanging around for a bit. Hopefully some of these incredible projects will inspire you to make the most out of your longer than expected downtime.
No doubt that every hacker has already heard of Digi-Key, the electronic component distributor that makes it just as possible to order one of something as it is to order a thousand of it. As an essential business, Digi-Key has been open during the duration of the lockdown since they support critical manufacturing services for virtually every industry on the planet including the medical industry.
They developed a UV light tunnel that wraps around the conveyor rollers. The design includes a sensor and a timer to control when and how long the UV lights are on. The totes are a frequent touch point for employees, and running incoming shipments through the UV light tunnel helps decrease the chance of exposure.