Year: 2015

Hand Controlled Robot Uses Accelerometer

August 16, 2015 by 3 Comments

What do orchestra conductors, wizards, and Leap controller users have in common? They all control things by just waving their hands. [Saddam] must have wanted the same effect, so he created a robot that he controls over wireless using hand gestures.

An accelerometer reads hand motions and sends them via an RF module to an Arduino. This is a bit of a trick, because the device produces an analog value and [Saddam] uses some comparators to digitize the signal for the RF transmitter. There is no Arduino or other CPU on the transmit side (other than whatever is in the RF module).

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Design Diary: Varactor-Tuned Regen Receiver

August 16, 2015 by 19 Comments

[QRP Gaijin] likes to build regenerative receivers. If you’ve ever built a serious one, you know there are (at least) two problems: One is you need a variable capacitor (hard to find these days). The other annoyance is that if you cover a wide frequency range, you probably need more than one coil.

[QRP Gaijin’s] latest radio design doesn’t have either of these problems. He uses a coil with a single pole double throw switch to bandswitch a single coil. There is no traditional main tuning capacitor. Instead a 1SV149 varactor provides the radio’s main tuning capacity (the diode tunes between 35 to 500 pF).

The post provides a nice design and a neat looking build in a Tupperware container (well… the outside is neat, at least; the inside is… best left inside the Tupperware). Better still, [QRP Gaijin’s] post details how he got to the final design, starting with the idea, and detailing the original design and the changes he made along the way. He also used data from an earlier build to limit how much the regeneration control has to be changed over wide frequencies and details how that changed the design. The prototype actually lacks the planned bandswitch, but will cover 3 to 30 MHz with the right coil.

There are certainly simpler regenerative receivers out there. However, the sophistication of this design along with the details of the designer’s thought processes makes this an interesting intermediate weekend project.

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Control the heat with a PID

Cozy Heat Control With An Arduino

August 16, 2015 by 22 Comments

[George Dewar] and his wife live in a typical 1940’s house in New Zealand , which in case you didn’t know, have a little insulation in the ceiling… and nowhere else. Like most, they put up with the cold — but after having a baby, [George] decided it was time to start controlling the heat a bit better.

They have an electric oil radiator which works well, but isn’t very smart. It only has 6 settings — not very useful when you’re trying to stay at a certain temperature. First off, they looked into a plug-in thermostat controller, and found a cheap one called the HeaterMate. Unfortunately it left a lot to be desired. For example, it didn’t seem to have PID control at all — and for an oil radiator, when you turn it off… it’s still going to heat the room for a while. He also found that because of the high current load of a heater … the device would read a few degrees over room temperature when operating. Unperturbed, [George] took this opportunity to design and build his own PID thermostat controller instead.  Continue reading “Cozy Heat Control With An Arduino” →

New Version Of Raspberry Pi Thin Client

August 16, 2015 by 18 Comments

It is funny how many times you use your full-blown PC as a terminal to another computer (which is quite often not as capable as the terminal computer). If all you need is a remote display and keyboard, a Raspberry PI would be enough. One of the newer Pi 2 boards would be even better.

You could roll your own set of remote access software, but you don’t have to. [Gibbio] has already created a thin client image called RPiTC and recently released version 1.4. The build supports diverse remote protocols including Microsoft Remote Desktop, Citrix, VMWare, and even X3270.

It supports WiFi and VPN. We were a little disappointed that it didn’t seem to have any serial communication programs (in case we wanted to build one into an old TeleType case). Of course, it is just a Linux system so you can install anything you want or need.

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Commodore C16 Resurrection With A Raspberry Pi

August 16, 2015 by 27 Comments

[lactobacillusprime] had a non-working Commodore C16 and too many Raspberry Pi computers, so he decided to bring the C16 back to life by emulating it on the Pi. At the heart of the project is the Pi, along with a small board that converts the old style Commodore keyboards (and joysticks) to a USB port.

Once you have the keyboard as a USB port, the rest of the project is more or less mechanics and software. [lactobacillusprime] did a nice job of getting everything in the new case, along with all the I/O wires routed through the existing ports. For software, Emulation Station does the job of launching the Commodore emulation on the Pi.

Of course, there’s no reason to limit yourself to just the Commodore emulator. Emulation Station along with the right back end emulators will allow this machine to play games that no real Commodore C16 could.

Of course, we were happiest to see him boot up Commodore 64 BASIC. Perhaps we should complete all those half finished C64 BASIC projects we started back in the 1980’s. In general, we hate to see old computers gutted instead of repaired, but at least this one will continue running its software. If you are upset about seeing a machine gutted,  you can always switch over to our previous coverage of putting Commodore guts in a new box.

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Hacking An SD Slot For WiFi

August 15, 2015 by 28 Comments

Back in the 1990’s moving files via a floppy disk was known as “sneaker net.” While floppies are a thing of the past, SD Cards are the modern equivalent and they still lend themselves to sneaker net operations.

But why? WiFi is everywhere now. Wouldn’t it be great if you could hack those devices with SD slots to use WiFi? Apparently 3D printer [extrud3d] thought the same thing and found a way to reconfigure a Toshiba FlashAir card to put his 3D printer on the network.

The card is aimed at consumers, so by default it creates a hotspot and waits for a connection, a rudimentary web app allows you to move files back and forth over the network to the SD card which is then read by the host device. However, [extrud3d] shows how to modify a file on the SD card’s file system to allow the device to hook up to an existing wireless network and also provides a Python script to make the file transfer easier.

Although this hack is for a 3D printer, it ought to work with most devices that have a full sized SD slot (or can be adapted to take a full sized card). Since the hack is nothing more than changing a text file, it is a lot easier than some other SD hacks we’ve covered. Over on hackaday.io, [Chris Jones] has recently done some hacking on the FlashAir and has a list of its shell commands if you want to go beyond the text file hacks.

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Tiny Robot Shakes Head At You In Disapproval

August 15, 2015 by 5 Comments

If you don’t have enough things staring at you and shaking their head in frustration, [Sheerforce] has a neat project for you. It’s a small Arduino-powered robot that uses an ultrasonic distance finder to keep pointing towards the closest thing it can find. Generally, that would be you.

When it finds something, it tries to track it by constantly rotating the distance finder slightly and retesting the distance, giving the impression of constantly shaking its head at you in disappointment. This ensures that you will either unplug it or smash it with a hammer after a very short time, but you should read [Sheerforce]’s code first: it’s a great example of documenting this for experimenters who want to build something that offers more affirmations of your life choices.

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