A harpsichord that plays itself

[Malcolm Messiter] is an Oboe player who loves to play pieces from the Baroque era. This often means playing with a Harpsichord and he managed to acquire one to call his very own. Unfortunately you can’t play both instruments at once so he set out to automate the keyboard. What you see here is a fully working version, but he soon went on to add solenoids to the upper rank as well. His story starts on page 27 of this newsletter (PDF).

He really went out of his way to make sure the instrument was not mistreated. A cabinet-maker built some brackets to mount the system above the keys. A friend drilled and tapped a sheet of acrylic to which each solenoid was mounted. The solenoid shafts have each been padded with felt to cushion the blow on the keys. We’ve embedded two demo video after the break that show off the first and second versions of the builds.

Harpsichords pluck the strings instead of hitting them with a hammer as the piano does. The mechanism that does the plucking had worn out on many of the keys so [Malcolm] used a 3D printer to help replace them.

[Read more...]

Halloween Props: Spooky eyes light up the bushes

This is just one example of several pairs of spooky eyes which light up [Vato Supreme's] bushes this Halloween. The quick and inexpensive build process make it a perfect diy decoration.

Each eye is made up of a ping-pong ball and an LED. But that alone won’t be very spook as the entire ball will glow rather brightly. So he spiced things up a bit by masking off the shape of a pupil and spraying the balls black. The vertical slit seen in white above will glow red like a demon in the night.

The LEDs are driven by an ATtiny85 running the Arduino bootloader. [Vato] found there was plenty of space two write code which fades the eyes in and out using PWM. This happens at random intervals for each of the four pairs he is driving.

We’ve seen a similar project that used oversized LEDs as the eyes. But we really like the idea of using a diffuser like this one. See it in action after the break.

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SNES emulator has it’s slot sealed shut

If you look closely you’ll notice there’s nowhere to put the game cartridge on this Super Nintendo system. That’s because this is a Rasberry Pi based SNES emulator that plays ROMs, not cartridges. Since the RPi board is used the only limit to what you can play is the board’s RAM and which ROMs you have on the SD card.

The case has basically been gutted and the unused cartridge slot was sealed with some Bondo before painting. In addition to the Rasberry Pi you’ll find a 7-port powered USB hub and a Teensy microcontroller board. The hub allows for the controllers to be connected via USB. The Teensy is recognized as a USB HID device and is used to connect the reset button to a functions on the emulator program. The power switch still works too. To make this happen [MIDItheKID] spliced a USB connector and a microB USB connector to the power switch. We think this draws power from the hub but we’re not 100% sure.

[MIDItheKID] mentions in the Reddit comments that he’s thinking of grabbing that new RPi that has more memory and doing some similar work on his dead PSX.

Robot performing a tightrope act

This robot is able walk the tightrope (translated). Well, it’s more of a shuffle than a walk, but still a lot better than we could do.

In the video after the break you can see the bot starting on the platform to the right. As it steps out onto the wire (which rides in a groove on the bottom of its foot) the robot spreads its arms to help maintain balance. When the other foot leaves the platform that is the last stride we will see until it reaches the other side. The rest of the act consists of sliding the feet a little bit at a time until it gets all the way across.

[Dr. Guero] has been working on at least one other balancer as well. Also embedded after the break is a robot riding a bicycle. It actually puts a foot down when stopped, and gives a stuttering push-off to get going again. This guy would be right at home riding past you in the hallways of the Death Star.

[Read more...]

APRS iGate built using a Raspberry Pi

The hardware seen above is used to bridge a local RF radio network to the APRS-IS network. The APRS-IS is an Internet Service that uses a web connection to communicate between APRS networks in different parts of the world. The Raspberry Pi is perfect for this application because of its ability to connect to a network, and its native use of Linux.

On the software side the majority of the work is done by a Python script. It is responsible for setting up and monitoring a connection with an APRS-IS server. To connect to the handheld radio unit a USB sound card was used. The Multimon package is used to send and receive audio packets through this hardware.

[Sunny] has a few upgrades planned for the system. The device needs to report its location to the APRS-IS server and the plan is to add functionality that will look of the WiFi AP’s location automatically. It may also be possible to get rid of the radio all together and use a DVB dongle as a software defined radio.

Red-bullet: cooking stove from cans, fueled by gas additive

A couple of beverage containers and a little bit of fuel additive bring together this aluminum can stove project. When lit it shoots flames out each of those holes around the top to heat the vessel resting upon it. [Peter Geiger] calls it the Red-Bullet because one of the stove pieces started as a Red Bull can and the other piece was a Coors (aka silver bullet).

This is basically an alcohol stove. We remember seeing a very well designed version of the penny stove several years back. This is different as it uses a side burner so the stove itself functions as the kettle stand. [Peter] started by cutting the Red Bull can just a bit taller than the final height. He then inserted the top portion of one of those aluminum beer cans that are shaped like glass bottles. The neck was lopped off and inverted. It is joined with the other can base using JB weld and by rolling the aluminum in on itself. After that has dried the holes are added and it’s filled with HEET from a yellow bottle. This gasoline additive is meant to sequester water and keep your gas line from freezing. The yellow bottle is mainly alcohol, the red is methanol so make sure you use the right one!

Building a Raspi case in true Hackaday fashion

[Ben] needed a case for his Raspberry Pi. Instead of going the usual laser-cut plastic or 3D printed route, he took a path far more familiar to us here at Hackaday. His case is built out of aluminum found in his basement, providing a neat reuse for some old aluminum extrusion he had lying around.

Part one of [Ben]‘s thoroughly documented build goes over the process of acquiring some of this very handy aluminum extrusion. Part two covers a very neat feature of [Ben]‘s scrap of aluminum: because of a pair of internal chamfers, [Ben] was able to mount his Raspi and USB hub to a separate piece of PVC and slide the whole assembly in.

The final assembly included dremeling a piece of aluminum plate for the Raspi and USB hub ports and wiring the whole thing together.

Right now the newly enclosed Raspi is working happily as [Ben]‘s home server. Not exactly the use case a rugged aluminum case would see the best use from, but it looks great all the same.

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