Swollen Clock Build Demostrates All Engineering Shoulds

June 26, 2015 by Mike Szczys 19 Comments

[Steve Gardner] wants an accurate clock for his bench. Of course the only option most engineers will accept for something like this a clock they’ve built themselves. In fact, this is his second time around as his first was an OLED based system using one of those sweet Maxim TCXO’s that keep time for years with negligible drift.

This build is going to be dead accurate as well since he plans to roll in a GPS source. But for now he’s covering the display build itself and will use another clock source IC at first. The display is a set of six 2.3″ 7-segment displays on protoboard. Bonus points for all the tidiness in his point to point soldering!

You may think this is a super simple project, and in a way it is. But [Steve] does an amazing job of dotting all the i’s and crossing all the t’s in a way that is beneficial to learn for all of your prototyping. For instance, he’s combining some 7-segment displays with 5mm LEDs as the colons. He mentions checking the peak wavelength of the displays to match the LEDs when choosing components. The design is also well-planned on graph paper. This may be just for use in illustrating the video but is a great practice in your own prototyping.

We’re not sure if there’s some movie magic involved here as his first burning of code to the PIC microcontroller results in a fully working device — impressive. Looking at his entire presentation, if you follow the workflow that [Steve] uses in his engineering, you’re doing it right!

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A Kitchen Timer Fit For MacGyver

February 27, 2015 by Rick Osgood 39 Comments

Here’s a project that you don’t want to bring into an airport, ship through the mail, or probably even remove from your home. [ProjectGeek] has built himself a simple kitchen timer masquerading as a bomb. The build is actually pretty simple, but the end result is something that would look at home in a Hollywood action flick.

The timer circuit is built from four simple components. An 8051 microcontroller board is used as the primary controller and timer. The code is available on GitHub. This board is attached to a another board containing four momentary push buttons. These are used to program the timer and to stop the buzzing. Another board containing four 7-segment displays is used to show the remaining time on the timer. A simple piezo buzzer is used to actually alert you when the timer has run out. All of these components are connected with colorful jumper wires.

The physical part of this build is made from easily available components. Old newspapers are rolled up to form the “explosive” sticks. These are then covered in plain brown paper ordinarily used to cover text books. The rolls are bundled together and fixed with electrical tape. The electronics can then be attached to the base with some hot glue or double-sided tape.

DIY Hot Wheels Drag Race Timer

January 19, 2015 by Rick Osgood 25 Comments

[Apachexmd] wanted to do something fun for his three-year-old son’s birthday party. Knowing how cool race cars are, he opted to build his own Hot Wheels drag race timer. He didn’t take the easy way out either. He put both his electronics and 3D printing skills to the test with this project.

The system has two main components. First, there’s the starting gate. The cars all have to leave the gate at the same time for a fair race, so [Apachexmd] needed a way to make this electronically controlled. His solution was to use a servo connected to a hinge. The hinge has four machine screws, one for each car. When the servo is rotated in one direction, the hinge pushes the screws out through holes in the track. This keeps the cars from moving on the downward slope. When the start button is pressed, the screws are pulled back and the cars are free to let gravity take over.

The second component is the finish line. Underneath the track are four laser diodes. These shine upwards through holes drilled into the track. Four phototransistors are mounted up above. These act as sensors to detect when the laser beam is broken by a car. It works similarly to a laser trip wire alarm system. The sensors are aimed downwards and covered in black tape to block out extra light noise.

Also above the track are eight 7-segment displays; two for each car. The system is able to keep track of the order in which the cars cross the finish line. When the race ends, it displays which place each car came in above the corresponding track. The system also keeps track of the winning car’s time in seconds and displays this on the display as well.

The system runs on an Arduino and is built almost exclusively out of custom designed 3D printed components. Since all of the components are designed to fit perfectly, the end result is a very slick race timer. Maybe next [Apachexmd] can add in a radar gun to clock top speed. Check out the video below to see it in action. Continue reading “DIY Hot Wheels Drag Race Timer” →

The Original Seven (Eight?) Segment Display

January 9, 2015 by Elliot Williams 36 Comments

The seven-segment LED display is ubiquitous. But how old do you think the fundamental idea behind it is? You nixie tube fans will be thinking of the vacuum-tube era, but a reader sent us this patent filed in 1908 where [Frank W. Wood] builds a numeric display with plain-vanilla light bulbs, slots cut in wood, and lots of wires.

The OCR on the patent is poorly done — you’re going to want to download the PDF and read it locally. But as it states in the patent, “Referring again to Fig. 1, the novel arrangement of the lamp compartments will be readily understood.”

Technically it’s not a seven-segment display at all. [F.W. Wood] designed these really nice-looking “4”s with the diagonal heads, and so he needed eight segments per digit. But the basic idea shines through, if you pardon the pun.

The other figures demonstrate the machine that’s used to send the signals to light up the lights. It’s a rotating drum with the right contacts on the bottom side to make connections and turn on the right lights at the other end. Low tech, but it’s what was available at the time.

We’re stoked that we’re not responsible for wiring this thing up, and we’re a bit awed by how old the spirit behind one of our most ubiquitous technologies is.

Thanks to [mario59] for the nostalgic tip!

Lego Technic Mechanical Seven Segment Display

August 7, 2014 by James Hobson 12 Comments

TeemingColdDiplodocus

Here’s a rather mesmerizing piece of Lego genius, displayed as a .GIF for your enjoyment. It’s a 7-segment display that is completely mechanical!

Built by [aeh5040], this beauty features 7 separate linkages that control each display segment. It’s powered off of a single motor which rotates a cylinder covered in small protrusions, similar to how music boxes work. As the cylinder rotates, the protrusions knock the main drive gears back and forth, flipping each segment between the ON and OFF states through a series of axle joints and bevel gears.

It makes rather satisfying sounds too!

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