Everyone has been learning how to stream this year whether they want to or not. This has given rise to the embarrassment paradox, which states that the more urgently you need to kill your camera and microphone feeds in a videoconference call, the more difficult and time-consuming it will be. Zoom in particular will toggle the mic and camera with keyboard shortcuts, but when your toddler waddles into the room swinging a used diaper around in the air, keyboard shortcuts will seem woefully under-powered.

What you need is a single sturdy button that sends both of these toggle commands as quickly as possible. [Simon Prickett]’s panic switch does exactly that. It’s a delightfully tactile arcade button connected to a Trinket M0, which can emulate a keyboard quite easily as an Arduino or CircuitPython device.

This little keyboard doesn’t send these macros directly, because that would be way too risky. What if you were reading Hackaday instead of staring into the tiled faces of your coworkers? Then it wouldn’t work, because Zoom is out of focus.

Instead, it sends an obscure four-key macro to the computer that triggers an AppleScript. [Simon]’s AppleScript checks to see if Zoom is running. If not, it has the system announce the fact. If it is running, then the script sends cmd+shift+a and cmd+shift+v to Zoom directly to toggle the audio and video. Check out the demo after the break.

As you might expect, we’ve seen a couple of videoconference survival hacks over the past few months. Need to show something or work with your hands, but only have one camera? All you need is a mirror, a clothespin, and a length of wire for a simple split-screen setup.

source https://hackaday.com/2020/07/29/panic-button-is-an-audio-visual-parachute-out-of-zoom-calls/

Everyone has been learning how to stream this year whether they want to or not. This has given rise to the embarrassment paradox, which states that the more urgently you need to kill your camera and microphone feeds in a videoconference call, the more difficult and time-consuming it will be. Zoom in particular will toggle the mic and camera with keyboard shortcuts, but when your toddler waddles into the room swinging a used diaper around in the air, keyboard shortcuts will seem woefully under-powered.

What you need is a single sturdy button that sends both of these toggle commands as quickly as possible. [Simon Prickett]’s panic switch does exactly that. It’s a delightfully tactile arcade button connected to a Trinket M0, which can emulate a keyboard quite easily as an Arduino or CircuitPython device.

This little keyboard doesn’t send these macros directly, because that would be way too risky. What if you were reading Hackaday instead of staring into the tiled faces of your coworkers? Then it wouldn’t work, because Zoom is out of focus.

Instead, it sends an obscure four-key macro to the computer that triggers an AppleScript. [Simon]’s AppleScript checks to see if Zoom is running. If not, it has the system announce the fact. If it is running, then the script sends cmd+shift+a and cmd+shift+v to Zoom directly to toggle the audio and video. Check out the demo after the break.

As you might expect, we’ve seen a couple of videoconference survival hacks over the past few months. Need to show something or work with your hands, but only have one camera? All you need is a mirror, a clothespin, and a length of wire for a simple split-screen setup.

source https://hackaday.com/2020/07/29/panic-button-is-an-audio-visual-parachute-out-of-zoom-calls/

You might think the smell of an electrolytic capacitor boiling out is bad, but if scientists from the University of Sydney have their way, that might be nothing. They’ve devised an ultracapacitor — that uses biomass from the stinky durian fruit along with jackfruit. We assume the capacitors don’t stink in normal use, but we wouldn’t want to overload one and let the smoke out.

One of the things we found interesting about this is that the process seemed like something you might be able to reproduce in a garage. Sure, there were a few exotic steps like using a vacuum oven and a furnace with nitrogen, and you’d need some ability to handle chemicals like vinylidene fluoride. However, the hacker community has found ways to create lots of things with common tools, and we would imagine creating aerogels from some fruit ought not be out of reach.

Not to spoil the surprise, but the stinky durian fruit had better power density. The paper claims that the performance is mainly due to the gels having a large surface area and porous structures along with the presence of pyridinic and graphitic nitrogen. The material outperforms several other organic capacitors as well as graphene nanosheets. That information, by the way, is buried in the supplement to the paper if you would like to see the comparison table.

Does this mean we will see cars running on fruit soon? Probably not. There’s an equal chance it will use dog fur and dryer lint.

source https://hackaday.com/2020/07/29/ultracapacitors-might-have-bad-fruity-smell/

Its safe to say that colour television is taken for granted nowadays. Consumed by the modern marketing jargon of colour dynamic range, colour space accuracy and depth, it is easy to overlook the humble beginnings of image reproduction when simply reconstructing an image with the slightest hint of colour required some serious ingenuity and earned you a well deserved pat on the back!

[anfractuosus] revisited an old gem of a technique, first patented in 1903 and used it to successful make an old monochrome TV produce a colour image. The idea in essence, is actually similar to what cheap image sensors and LCDs still use today. Rather than relying on true RGB colour generation by individually integrating colour sources as AMOLED does, we take an easier route: Produce a simpler monochrome image where each colour pixel is physically represented by four monochrome sub-pixels, one for each colour component. Now light up each of the sub-pixels according to the colour information of your image and rely on an external colour filter array to combine and spit out the correct colours.

He first used some image processing to convert a standard colour video into the aforementioned monochrome sub-pixel representation. Next, a Bayer colour filter array was printed on some acetate sheets using an inkjet printer (the original inventors used potato starch!), which when overlaid on top of the monochrome monitor, magically result in colour output.

There are some problems associated with this technique, mainly to do with the difficulty in measuring the size of the TV pixels and then producing and perfectly aligning a filter sheet for it. You should check out how [anfractuosus] went about solving those issues.

So now you know a bit more about colour image generation, but how about colour TV transmission? Check out an earlier piece to learn more.

source https://hackaday.com/2020/07/28/trick-from-1903-makes-an-old-monochrome-tv-spit-some-colours/

There was a time when it was easy to eavesdrop on police and other service radio networks. Police scanners fans can hear live police, fire, and ambulance calls. However, it isn’t as easy as it used to be because nearly all radios now are trunked. That means conversations might jump from channel to channel. However, P25 can unscramble trunked radio calls intercepted by a cheap SDR dongle and let you listen in. [SignalsEverywhere] shows you how to set it up for Windows or Linux and you can see the video below.

Trunking radio makes sense. In the old days, you might have a dozen channels for different purposes. But most channels would be empty most of the time. With trunking radio, a radio’s computer is set to be in a talk group and a control channel sorts out what channel the talk group should use at any given time. That means that one channel might have several transmissions in a row from different talk groups and one talk group might hop to a new channel on each transmission.

P25 is the APCO ( Association of Public Safety Communications Officials) Project 25 standard used for public service trunking radios. You can, of course, get commercial equipment to monitor these radios, too, but what fun is that?

With everyone spending more time at home these days, radio monitoring is a great way to live vicariously. Not the first time we’ve seen an SDR dongle scanner, of course. Just watch out for kiddy toys.

source https://hackaday.com/2020/07/28/trunking-police-scanning-with-sdrtrunk/

[splat238] had a ton of spare sensors laying around that he had either bought for a separate project or on an impulse buy, so he knew he had to do something with them. He decided to build his own digital multi-tool focusing on sensors that would be particularly useful in a workshop setting. Coincidentally, he was inspired by a previous hack that we covered a while back.

He’s equipped his device with a bubble level, tachometer, IR thermometer, protractor, laser pointer, and many, many more features that would make great additions to any hacker’s workspace. There’s a good summary of each sensor, making his Instructable somewhat of a quick guide to common sensing modalities for hardware designers. The tachometer, thermometer, laser pointer, and a few other capabilities are notable upgrades from the project we highlighted previously. We also appreciate the bigger display, allowing for more detailed user feedback particularly in using the compass and bullseye digital level among other features.

The number of components in [splat238’s] build is too extensive to detail one-by-one in this article, so please see his Instructable linked above for all the details. [splat238] made his own PCB for mounting each sensor and did a good job making the design modular so you wouldn’t need to add certain components if you don’t need them. Most of the components take some through-hole soldering with only a handful of 0805 resistors required otherwise. The housing was designed such that the user can handle the tool with one hand and can switch between each function with a push of a button.

Finally, the device is powered using a rechargeable lithium-polymer battery making it very reusable. And, if there weren’t enough features already, the battery can be charged via USB or through two solar panels mounted into the housing unit. Okay, solar charging might be a case of featuritis, but still a cool build either way.

Check out some other handy DIY tools on Hackaday.

 

source https://hackaday.com/2020/07/28/the-swiss-army-knife-of-bench-tools/