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The Pi Zero Mass Storage Picture Frame

March 25, 2016 by 39 Comments

The Raspberry Pi Zero – and the not-perpetually-out-of-stock Raspberry Pi A+ – only have one USB port, but behind that port is a lot of functionality. This is an OTG USB port, and just like the USB port on your smartphone, this little plug can become any kind of USB device. Transforming the Pi into a USB gadget allows it to be a serial connection, MIDI device, audio source or sink, or a USB mass storage device.

[Francesco] was especially interested in the USB mass storage capability of the Raspberry Pi Zero and built a small project to show off its capabilities. He turned a Pi Zero into the controller for a digital picture frame, constantly displaying all the image files on a small screen.

The build started with [Andrew Mulholland]’s guide for Pi Zero OTG modes, with just a few modifications. When the Pi is plugged into a PC, it automatically becomes a 100 Megabyte USB storage device. You don’t need that much space on a digital picture frame, anyway.

While setting up a digital picture frame is easy enough, there’s still a tremendous amount of untapped potential in using the Pi Zero as a USB gadget. With enough buttons, switches, and sensors, the Pi can become a wearable MIDI device, or with the Pi camera module, an IP webcam. Neat stuff, and we can’t wait to see what the community comes up with next.

Flying Close To The Flame: Designing Past Specified Limits

March 24, 2016 by 23 Comments

A very good question came up on The EEVBlog forum that I thought deserved an in depth answer. The poster asked why would amplifier companies in the heyday of tube technology operate tubes in mass produced circuits well in excess of their published manufacturers recommended limits. The simple answer is: because the could get away with it. So the real question worth exploring is how did they get away with operating outside of their own published limitations? Let’s jump in and take a look at the collection of reasons.

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An Affordable Panasonic Grid-EYE Thermal Imaging Camera

March 24, 2016 by 20 Comments

Thermal imaging cameras are objects of desire for hackers and makers everywhere, but sadly for us they can be rather expensive. When your sensor costs more than a laptop it puts a brake on hacking.

Thankfully help is at hand, in the form of an affordable evaluation board for the Panasonic Grid-EYE thermal imaging camera sensor. This sensor has sparked the interest of the Hackaday community before, featuring in a project that made the 2014 Hackaday Prize semifinals, but has proved extremely difficult to obtain.

All that has now changed though with this board. It features the Grid-EYE sensor itself, an Atmel ATSAM-D21G18A microcontroller, and onboard Bluetooth, but has an interesting feature that, as well as being a standalone device, can be used as an Arduino shield. A full range of APIs are provided, and the code is BSD licensed.

This module is not the highest-spec thermal imaging camera on the market by any means, after all it has a resolution of only 64 pixels in an 8×8 grid. But its affordability and easy availability should trigger a fresh crop of thermal camera projects in our community, and we applaud that.

Thermal camera projects have featured quite a few times here on Hackaday. Some have been based on the FLIR Lepton module, like this one that combines its image with a 640×480 visible camera and another that claims to be one of the smallest thermal cameras, while others have harnessed raw ingenuity to create a thermal camera without a sensor array. This pan-and tilt design for example, or this ingenious use of light painting. Please, keep them coming!

[via oomlout]

Growing Algae For Fun And Profit

March 23, 2016 by 53 Comments

Supposedly, writes [Severin], algae is a super food, can be used as biofuel, and even be made into yoga mats. So he’s built an algal reactor at Munich Maker Lab, to try to achieve a decent algal yield.

You might expect that  sourcing live algae would be as simple as scraping up a bit of green slime from a nearby pond, but that yields an uncertain mix of species. [Severin] wanted Chlorella algae for his experiment because its high fat content makes it suitable for biodiesel experiments, so had to source his culture from an aquatic shop.

The reactor takes the form of a spiral of transparent plastic tube surrounding a CFL lamp as a light source, all mounted on a lasercut wooden enclosure housing a pump. A separate glass jar forms a reservoir for the algal-rich water. He does not mention whether or not he adds any nutrient to the mix.

Left to its own devices the machine seems to work rather well, a 48 hour session yielding an impressively green algal soup. Sustained running does cause a problem though, the pipes block up with accumulated algae and the machine needs cleaning by blasting it with high pressure water and a healthy dose of nuts and bolts.

This isn’t the first algal reactor we’ve featured here on Hackaday, we had this Arduino-powered one back in 2009. But mostly the algae that have appeared here have been of the bioluminescent variety, as with this teaching project, or this night light.

Michael Ossmann Makes You An RF Design Hero

March 23, 2016 by 45 Comments

To a lot of people, radio-frequency (RF) design is black magic. Even if you’ve built a number of RF projects, and worked your way through the low-lying gotchas, you’ve probably still got a healthy respect for the gremlins lying in wait around every dimly-lit corner. Well, [Michael Ossmann] gave a super workshop at the Hackaday Superconference to give you a guided tour of the better-illuminated spaces in RF design.

five_rules[Michael] is a hacker-designer, and his insights into RF circuit design are hard-won, by making stuff. The HackRF One is probably his most famous (and complex) project, but he’s also designed and built a number of simpler RF devices. And the main point of his talk is that there’s a large range of interesting projects that are possible without getting yourself into the fringes of RF design (which require expensive test equipment, serious modelling, or a Ph.D. in electro-wavey-things).

You should watch [Mike]’s workshop which is embedded below. That said, here’s the spoilers. [Mike] suggests five rules that’ll keep your RF design on the green, rather than off in the rough.

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Unlock The Phase Locked Loop

March 23, 2016 by 23 Comments

If you want a stable oscillator, you usually think of using a crystal. The piezoelectric qualities of quartz means that it can be cut in a particular way that it will oscillate at a very precise frequency. If you present a constant load and keep the temperature stable, a crystal oscillator will maintain its frequency better than most other options.

There are downsides to crystals, though. As you might expect, because crystals are so stable it’s hard to change the frequency much when you want a different one. You can use a trimming capacitor to pull the frequency a little, but to really change frequency, you have to change crystals.

There are other kinds of oscillators that are more frequency agile. However, they aren’t usually as stable. To combine flexibility with crystal-like stability, you can use a Phase Locked Loop (PLL). Many modern systems use direct digital synthesis, but the PLL is a venerable and time-tested technique.

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The Internet Enabled Kill-A-Watt

March 22, 2016 by 47 Comments

The Internet of Things has been applied to toasters, refrigerators, Christmas lights, Barbies, and socks. Unsurprisingly, the Internet of Things has yet to happen – that would require a useful application of putting the Internet in random devices. One of the best ideas is a smart electric meter, but the idea behind this is to give the power company information on how much electricity you’re using, not give you an idea of how much power you’re pulling down. The answer to this is the Internet-enabled Kill-A-Watt, and that’s exactly what [Solenoid] is building for his entry into the Hackaday Prize.

Modern power meters have an LED somewhere on the device that blinks every time a Watt is used. This is the data [Solenoid]’s creation is pushing up to the Internet to relay power consumption to himself or anyone else in the world.

The hardware, like many upcoming Hackaday Prize entries, we’re sure, is based on the ESP8266 WiFi module, with a light sensor, SD card reader, and OLED display. It’s meant to mount directly to a power meter, recording power consumption and pushing that data up the network. It’s simple, but it also allows for very granular monitoring of [Solenoid]’s power consumption, something the electric company’s smart meters can’t compete with.

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