RC Drag Racing Christmas Tree And Speed Trap

September 20, 2016 by 11 Comments

In the drag racing world, a Christmas tree is the post at the start line that sequentially lights up a set of yellow lights followed shortly after by a green light to tell the drivers to go, the lights obviously giving it its seasonal name. Included at the base of the tree are lasers to detect the presence of the cars.

[Mike] not only made his own Christmas tree for his RC cars, but he even made an end-of-track circuit with LED displays telling the cars how long they took. Both start and finish hardware are controlled by Pololu Wixel boards which has TI CC2511F32 microcontrollers with built-in 2.4 GHz radios for wireless communications.

In addition to the LEDs, the Christmas tree has a laser beam using a 650nm red laser diode for each car at the start line that’s aimed at a TEPT5600 phototransistor. If a car crosses its beam before the green light then a red light signals the car’s disqualification.

The end-of-track circuit has 7-segment displays for each car’s time. [Mike] designed the system so that the Christmas tree’s microcontroller tells the end-of-track circuit’s microcontroller when to reset the times, start the times, and clear the times should there be a disqualification. The finish line controller has lasers and phototransistors just like the starting line to stop the timers.

Oh, and did we mention that he also included 1980’s car racing game sounds? To see and hear it all in action check out the video after the break. If the cars seem a little drunk it’s because pushing left or right on the controller turns the wheel’s fully left or right.

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Ask Hackaday: Help Me Choose A ‘Scope

September 20, 2016 by 89 Comments

If there is one instrument that makes an electronic engineer’s bench, it is the oscilloscope. The ability to track voltages in the time domain and measure their period and amplitude is one akin to a light in the darkness, it turns a mere tinkerer with circuits into one in command of them. Straightforward add-on circuits can transform a basic oscilloscope into a curve tracer, frequency response display, and much more, and modern oscilloscopes offer a dizzying array of useful measurement features unimaginable to engineers only a few years ago. And I need your help to pick a new one.

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Absolute 3D Tracking With EM Fields

September 20, 2016 by 28 Comments

[Chris Gunawardena] is still holding his breath on Valve and Facebook surprising everyone by open sourcing their top secret VR prototypes. They have some really clever ways to track the exact location and orientation of the big black box they want people to strap to their faces. Until then, though, he decided to take his own stab at the 3D tracking problems they had to solve. 

While they used light to perform the localization, he wanted to experiment with using electromagnetic fields to perform the same function. Every phone these days has a magnetometer built in. It’s used to figure out which way is up, but it can also measure the local strength of magnetic fields.

Unfortunately to get really good range on a magnetic field there’s a pesky problem involving inverse square laws. Some 9V batteries in series solved the high current DC voltage source problem and left him with magnetic field powerful enough to be detected almost ten centimeters away by his iPhone’s magnetometer.

As small as this range seems, it ended up being enough for his purposes. Using the existing math and a small iOS app he was able to perform rudimentary localization using EM fields. Pretty cool. He’s not done yet and hopes that a more sensitive magnetometer and a higher voltage power supply with let him achieve greater distances and accuracy in a future iteration.

An ESP8266 In Every Light Switch And Outlet

September 20, 2016 by 91 Comments

[Hristo Borisov] shows us his clever home automation project, a nicely packaged WiFi switchable wall socket. The ESP8266 has continuously proven itself to be a home automation panacea. Since the ESP8266 is practically a given at this point, the bragging rights have switched over to the skill with which the solution is implemented. By that metric, [Hristo]’s solution is pretty dang nice.

esp8266-smart-lightswitchIt’s all based around a simple board. An encapsulated power supply converts the 220V offered by the Bulgarian power authorities into two rails of 3.3V and 5V respectively. The 3.3V is used for an ESP8266 whose primary concern is the control of a triac and an RGB LED. The 5V is optional if the user decides to add a shield that needs it. That’s right, your light switches will now have their own shields that decide the complexity of the device.

The core module seen to the right contains the actual board. All it needs is AC on one side and something to switch or control on the other The enclosure is not shown (only the lid with the shield connectors is seen) but can be printed in a form factor that includes a cord to plug into an outlet, or with a metal flange to attach to an electrical box in the wall. The modules that mate with the core are also nicely packaged in a 3D printed shield. For example, to convert a lamp to wireless control, you use a shield with a power socket on it. To convert a light switch, use the control module that has a box flange and then any number of custom switch and display shields can be hot swapped on it.

It’s all controllable from command line, webpage, and even an iOS app; all of it is available on his GitHub. We’d love to hear your take on safety, modularity, and overall system design. We think [Hristo] has built a better light switch!

Hackaday Prize Entry: Mouse Controlled Microscope

September 19, 2016 by 9 Comments

You might imagine that all one should need to operate a microscope would be a good set of eyes. Unfortunately if you are an amputee that may not be the case. Veterinary lab work for example requires control of focus, as well as the ability to move the sample in both X and Y directions, and these are not tasks that can easily be performed simultaneously with only a single hand.

[ksk]’s solution to this problem is to use geared stepper motors and an Arduino Mega to allow the manual functions of the microscope to be controlled from a computer mouse or trackball. The motors are mounted on the microscope controls with a custom 3D-printed housing. A rotary selector on the control box containing the Arduino allows the user to select a slow or fast mode for fine or coarse adjustment.

It’s fair to say that this project is still a work in progress, we’re featuring it in our series of posts looking at Hackaday Prize entries. However judging by the progress reported so far it’s clear that this is a project with significant potential, and we can see the finished product could be of use to anyone operating the microscope.

We’ve featured one or two mouse controlled projects over the years, though not controlling microscopes. Here’s one mouse controlled robot arm, and we’ve covered another arm with a 3D mouse.

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The Cicada: A Parasite Art Piece With Commitment Issues

September 19, 2016 by 18 Comments

How often do you think deeply about the products around you? How about those you owned five years ago? Ten? The Cicada — brainchild of [Daniel Kerris] — is an art piece that aims to have the observer reflect on consumer culture, buyer’s remorse, and wanting what we cannot have.

The Cicada consists of an ultrasonic sensor feeding data to a Raspberry pi which — calculating the distance of an approaching human — either speeds up or slows down a servo motor connected to a General Electric Walkman’s cassette speed potentiometer. Upon detecting someone approaching, The Cicada begins to loop the chorus of Celine Dion’s “I Will Always Love You”. As you move closer, the tape speed slows, and there is a transition from love at first sight to nightmarish drawl as the music slows.

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Thermoelectric Dry Ice Generator Does Not Work (Yet)

September 19, 2016 by 83 Comments

[Pabr] is trying to make dry ice the hard way by building a thermoelectric dry ice generator. The project is a well planned round trip through thermodynamics and cryogenics with a hard landing on the icy grounds of trial and error.

[Pabr’s] four stage Peltier element on a heatsink.
While dry ice can be obtained with simpler methods, for example by venting gaseous CO2 from fire extinguishers and collecting the forming CO2 flakes, [pabr’s] method is indeed attractive as a more compact solid-state solution. The setup employs a four stage Peltier element, which uses four Peltier stages to achieve a high temperature differential.

With sufficient cooling on the high-temperature side of the element, it should be well capable of achieving temperatures below -78.5 °C, the sublimation temperature of CO2. So far, [pabr] has built three different setups to expose small amounts of CO2 to the cold of the Peltier element, hoping to observe the formation of little dry ice flakes.

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