Reproduce 3D Printed Models By Making Your Own Molds

October 17, 2012 by Mike Szczys 36 Comments

Need fifty copies of that 3D printed whirligig you’re so proud of? It might be faster to just cast copies by using the 3D printed model to make a mold. [Micah] found himself in this situation and managed to cast one copy every 10-12 minutes using the mold seen above.

With the object in hand, you need to find a container which will fit the mold without too much waste. The bottom half of the mold is then filled with modeling clay, a few uniquely shaped objects to act as keys, and the model itself. After getting a good coating of release agent the rest of the mold is filled with a silicone rubber product which is sold for mold making. This creates one half of the mold. After it cures the clay and key objects are removed, everything is sprayed with the release agent, and the other half of the mold is poured.

Now your 3D object can be copied by pouring two-part resins in the to shiny new mold.

Magic Finger Input Device Is A Camera On Your Finger Tip

October 16, 2012 by Mike Szczys 35 Comments

What if we could do away with mice and just wear a thimble as a control interface? That’s the concept behind Magic Finger. It adds as movement tracking sensor and RGB camera to your fingertip.

Touch screens are great, but what if you want to use any surface as an input? Then you grab the simplest of today’s standard inputs: a computer mouse. But take that one step further and think of the possibilities of using the mouse as a graphic input device in addition to a positional sensor. This concept allows Magic Finger to distinguish between many different materials. It knows the difference between your desk and a piece of paper. Furthermore, it opens the door to data transfer through a code scheme they call a micro matrix. It’s like a super small QR code which is read by the camera in the device.

The concept video found after the break shows off a lot of cool tricks used by the device. Our favorite is the tablet PC controlled by moving your finger on the back side of the device, instead of interrupting your line of sight and leaving fingerprints by touching the screen.

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Face Tracking With An Android Device

October 15, 2012 by Mike Szczys 7 Comments

This Android device can recognize faces and move to keep them in frame. It’s a proof of concept that uses commonly available parts and software packages.

The original motivation for the project was [Dan O’s] inclination to give the OpenCV software a try. OpenCV is an Open Source Computer Vision package that takes on the brunt of the job when it comes to discerning meaning from images. To give the phone the power to move he designed and printed his own mounting brackets for the phone and a couple of hobby servos. An IOIO board connects to the Android device in order to control the motors. On the software side all [Dan] needed to do was write some code to interface the output of the OpenCV face tracking modules with the input of the IOIO. See the finished project demonstration after the jump.

This system can easily be implemented with other hardware, like this Arduino-based version we looked at earlier in the year.

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Arduino Parking Lot Attendant

October 15, 2012 by Mike Szczys 25 Comments

Here’s an automatic parking gate for toy cars. There’s no need to press a button, the electronics detect the presence of a vehicle on either side of the gate, raising it after verifying that the lot is not already full. It’s the same idea as counting how many people enter a room in order to switch the lights but the hardware is just a bit different.

The system is controlled by a pair of sensors in the paper which serves as the parking lot. There are three sheets of heavy stock, the top and bottom both have aluminum foil on them, with the center layer as a separator. There are holes cut in the separator where the hash marks are seen above. By adding a little pressure to the car when you drive it up to the gate this completes a circuit instructing the Arduino that there’s a vehicle in position.

You can see a demonstration, as well as the guts of the build, in two videos after the break.

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Singing Pumpkins

October 15, 2012 by Mike Szczys 6 Comments

This Halloween table will sing a sweet serenade to spook your guests. Each of the animatronic pumpkins were quite easy to build, but you may end up spending a bit more time choreographing the performance.

Inside each Jack-o-lantern you’ll find a custom Arduino compatible board called a Minion board. These include a wireless connection which lets the system sync with the computer playing the audio. The pumpkins are fake, which means that can be reused year after year (unlike our LED matrix inside a real pumpkin). The mouth is connected to a servo with a short piece of bent wire, allowing it to flap along with the words of a song. You can see a performance of the Ghostbusters theme in the clip after the break.

A custom GUI was written in C# to aid in the choreography. It handles the playback of the song, with a few buttons that can be used to record the light and mouth effects. This ‘recording’ is then used to drive the pumpkins during a performance.

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Repairing A Junked Signal Generator

October 15, 2012 by Mike Szczys 21 Comments

We must be walking past the wrong dumpsters because we certainly haven’t encountered equipment like this just waiting to be salvaged. [Shahriar] found an HP 8648C Synthesized Signal Generator while he was ‘dumpster diving’ and set out to fix the malfunctioning lab equipment. He posted a 1-hour video on the project, which you can find embedded after the break. The actual fix happens in the first half, the rest of the video is spent testing the resurrected device.

The back corner of the case has been dented, which may be the reason this has been thrown out. When it is first powered it emits an unpleasant screeching noise and the user interface doesn’t do anything. [Shahriar] says he recognizes the sound as a malfunctioning switch-mode power supply. Sure enough, when disconnected from the main board it still makes the noise. It turns out there’s a huge electrolytic capacitor the size of a stack of poker chips which has come loose from the PSU board. When it’s resoldered the device fires up as expected.

Now how are we going to find a digital capture oscilloscope that just needs to have its PSU reassembled?

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7400 Project Encrypts And Decrypts Data

October 15, 2012 by Mike Szczys 8 Comments

[Nakul], [Nikilesh], and [Nischal] just finished posting about their entry in the 2012 Open 7400 Logic competition. It’s an encryption system based entirely on 7400 logic chips. The device operates on 8-bit binary numbers, which limits its real-world applications. But we bet they learned a lot during the development process.

The encryption algorithm is based on a the concept of cellular automaton. This is a something with which we’re already familiar having seen many Conway’s Game of Life projects around here. What we’re not familiar with is this particular wing of the concept called ‘Rule 30‘. It works well with this project because a complex pattern can be generated from simple beginnings.

After conceptualizing how the system might work the team spent some time transferring the implementation to the chips they had available. The end result is a quartet of chip-packed breadboards and a rat’s nets of wires, but the system is capable of both encrypting and decrypting data.