An Englishman’s Home Is His (Drone-Defended) Castle

November 9, 2018 by Jenny List 24 Comments

Retiring to the garden for a few reflective puffs on the meerschaum and a quick shufti through the Racing Post, and the peace of the afternoon is shattered by the buzz of a drone in the old airspace,what! What’s a chap to do, let loose with both barrels of the finest birdshot from the trusty twelve-bore? Or build a missile battery cunningly concealed in a dovecote? The latter is what [secretbatcave] did to protect his little slice of England, and while we’re not sure of its efficacy we’re still pretty taken with it. After all, who wouldn’t want a useless garden accoutrement that conceals a fearsome 21st century defence system?

The basic shell of the dovecote is made from laser cut ply, in the shape of an innocuous miniature house. The roof is in two sliding sections which glide apart upon servo-controlled drawer runners, and concealed within is the rocket launcher itself on a counterweighted arm to lift it through the opening. The (toy) rocket itelf is aimed with a camera pan/tilt mechanism,and the whole is under the control of a Raspberry Pi

It’s understood that this is a rather tongue-in-cheek project, and the chances of any multirotors falling out of the sky are somewhat remote. But it does serve also to bring a bit of light back onto a theme Hackaday have touched upon in previous years, that of the sometimes uneasy relationship between drone and public.

Raspberry Pi PoE Redux

November 9, 2018 by Jonathan Bennett 19 Comments

[Martin Rowan] was lucky enough to get his hands on the revised Power Over Ethernet (PoE) hat for the Raspberry Pi. Lucky for us, he wrote it up for our benefit, including inspection of the new hat, it’s circuit, and electrical testing to compare to the original hardware.

You may remember the original release of the PoE hat for the Raspberry Pi, as well as the subsequent recall due to over-current issues. In testing the revised board, [Martin] powered a test load off the USB ports, and pulled over an amp — The first iteration of the PoE hat would often trip the over-current protection at 300 milliamps.

This afternoon, the redesigned PoE board was officially released, and the post mortem of the problem documented in a blog post. It’s a lesson in the hidden complexity of hardware design, as well as a cautionary tale about the importance of thorough testing, even when the product is late and the pressure is on.

The PoE hat converts 48 volt power down to a 5 volt supply for the Pi using a flyback transformer. The problem was that this transformer setup doesn’t deliver clean steady 5 volt power, but instead provides power as a series of spikes. While these spikes were theoretically in spec for powering the Pi and usb devices, some Raspberry Pis were detecting those spikes as too much current pushed through the USB ports. The official solution essentially consists of better power filtering between the hat and the Pi, flattening that power draw.

We’re looking forward to getting our hands on this new and improved PoE Hat, and using it in many project to come.

Using E-Paper Displays For An Electronic Etch A Sketch

November 9, 2018 by Al Williams 12 Comments

Electronic things are often most successful when they duplicate some non-electronic thing. Most screens, then, are poor replacements for paper. Except, of course, for E-paper. These displays have high contrast even in sunlight and they hold their image even with no power. When [smbakeryt] was looking at his daughter’s Etch-a-Sketch, he decided duplicating its operation would be a great way to learn about these paper-like displays.

You can see a video of his results and his findings below. He bought several displays and shows them all, including some three-color units which add a single spot color. The one thing you’ll notice is the displays are slow which is probably why they haven’t taken over the world.

The displays connect to a Raspberry Pi and many of the displays are meant to mount directly to a Pi. The largest display is nearly six inches and some of the smaller displays are even flexible. It appears the three color displays were much slower than the ones that use two colors. To combat the slow update speeds, some of the displays can support partial refresh.

The drawing toy uses optical encoders connected to the Raspberry Pi. The Python code is available. Even if you don’t want to duplicate the toy, the comparison of the displays is worth watching. We were really hoping he’d included an accelerometer to erase it by shaking, but you’ll have to add that feature yourself. By the way, in the video, he mentions the real Etch-a-Sketch might work with magnets. It doesn’t. It is an aluminum powder that sticks to the plastic until a stylus rubs it off.

We’ve seen these displays many times before, of course. If you are patient enough, you can even use them as Linux displays.

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Pixy2 Is Super Vision For Arduino Or Raspberry Pi

November 9, 2018 by Al Williams 24 Comments

A Raspberry Pi with a camera is nothing new. But the Pixy2 camera can interface with a variety of microcontrollers and has enough smarts to detect objects, follow lines, or even read barcodes without help from the host computer. [DroneBot Workshop] has a review of the device and he’s very enthused about the camera. You can see the video below.

When you watch the video, you might wonder how much this camera will cost. Turns out it is about $60 which isn’t cheap but for the capabilities it offers it isn’t that much, either. The camera can detect lines, intersections, and barcodes plus any objects you want to train it to recognize. The camera also sports its own light source and dual servo motor drive meant for a pan and tilt mounting arrangement.

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The How And Why Of Laser Cutter Aiming

November 9, 2018 by Tom Nardi 16 Comments

Laser aficionado [Martin Raynsford] has built up experience with various laser cutters over the years and felt he should write up a blog post detailing his first-hand findings with an often overlooked aspect of the machines: aiming them. Cheap diode laser cutters and engravers operate in the visible part of the spectrum, but when you get into more powerful carbon dioxide lasers such as the one used in the popular K40 machines, the infrared beam is invisible to the naked eye. A secondary low-power laser helps to visualize the main laser’s alignment without actually cutting the target. There are a couple of ways to install an aiming system like this, but which way works better?