Tiny PIC Clock is Not a Tiny Bomb

It’s been a few weeks since the incident where Ahmed Mohamed, a student, had one of his inventions mistaken for a bomb by his school and the police, despite the device clearly being a clock. We asked for submissions of all of your clock builds to show our support for Ahmed, and the latest one is the tiniest yet but still has all of the features of a full-sized clock (none of which is explosions).

[Markus]’s tiny clock uses a PIC24 which is a small yet powerful chip. The timekeeping is done on an RTCC peripheral, and the clock’s seven segment displays are temporarily lit when the user presses a button. Since the LEDs aren’t on all the time, and the PIC only consumes a few microamps on standby, the clock can go for years on a single charge of the small lithium-ion battery in the back. There’s also a phototransistor which dims the display in the dark, and a white LED which could be used as a small flashlight in a pinch. If these features and the build technique look familiar it’s because of [Markus’] tiny MSP430 clock which he was showing around last year.

Both of his tiny clocks are quite impressive for their size, features, and power consumption. Some of the other clocks we’ve featured recently include robot clocks, clocks for social good, and clocks that are not just clocks (but still won’t explode). We’re suckers for a good clock project here, so keep sending them in!

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A Kitchen Timer Fit for MacGyver

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.

Hackaday Links: March 25, 2013

Illegal, yet impressive


Want a soda? Just grab a robot, shove it in a vending machine, and grab yourself one. This video is incredibly French, but it looks like we’ve got a custom-built robot made out of old printers and other miscellaneous motors and gears here. It’s actually pretty impressive when you consider 16 ounce cans weigh a pound.



Okay, we got a lot of emails on our tip line for this one. It’s a group buy for a programmable oscillator over on Tindie. Why is this cool? Well, this chip (an SI570) is used in a lot of software defined radio designs. Also, it’s incredibly hard to come by if you’re not ordering thousands of these at a time. Here’s a datasheet, now show us some builds with this oscillator.

Chiptune/keygen music anywhere


[Huan] has a co-loco’d Raspi and wanted a media server that is available anywhere, on any device. What he came up with is a service that streams chiptune music from your favorite keygens. You can access it with Chrome (no, we’re not linking directly to a Raspberry Pi), and it’s extremely efficient – his RAM usage didn’t increase a bit.

Take it on an airplane. Or mail it.


[Alex]’s hackerspace just had a series of lightning talks, where people with 45-minute long presentations try to condense their talk into 10 minutes. Of course the hackerspace needed some way to keep everything on schedule. A simple countdown timer was too boring, so they went with a fake, Hollywood-style bomb. No, it doesn’t explode, but it still looks really, really fake. That’s a good thing.

Printers have speakers now?


[ddrboxman] thought his reprap needed a nice ‘print finished’ notification. After adding a piezo to his electronics board, he whipped up a firmware hack that plays those old Nokia ringtones. The ringtones play over Gcode, so it’s possible to have audible warnings and notifications. Now if it could only play Snake.

Dropping the nitrogen bomb in science class

We took Geology in college. It was pretty cool learning about the hardness of different minerals. But there were no explosions involved. We’re not entirely sure what this class is, perhaps Chemistry, maybe Physics, but we want in. [Dr. Roy Lowry] wows the class with a bomb made of liquid nitrogen. The demonstration was part of his lecture at Plymouth University.

A small explosion is cool, but [Roy] knows how to add the wow factor. To make the bomb he filled a one liter plastic bottle about 1/3 of the way with liquid nitrogen. After tightly sealing the cap it was dropped in that garbage can which had a pool of warm water in it. Before quickly running away he and his assistant dumped a few garbage bags of ping-pong balls on top of it all. When the plastic bottle bursts under the pressure of the expanding gas it sends the garbage can about six feet into the air and floods the room with bouncing white balls. See the whole presentation for yourself in the clip after the break and don’t forget the sound so you can catch the oohs and aahs at the end.

Looks like a Hackerspace recruitment tool if we’ve ever seen one.

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Adding payload to an RC cessna

For just a few bucks you can add a payload to your flying toys. In this case it’s a Cessna RC plane which now has an added surprise. The first thing to be dropped was a parachute with a weight on it (for testing purposes). But there are hints of future projects that will use the same system for different purposes.

As you can see in the image above, the system depends on an additional compartment attached to the bottom of the plane. It was built from foam board to keep the weight down and connects using rare earth magnets. The bottom of the enclosure acts as the door, hinging on a servo motor with a bamboo skewer as the axle. So far the test drops have gone pretty well, but some more work needs to be done with the parachute design. It only opens about 60% of the time. We can sympathize, having had to work out some of our own parachute issues.

Don’t miss video from the plane as well as the ground after the break.

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Defusable alarm clock – wastes wire but fun for the kids

Nothing makes you feel the pressure of getting out of bed in the morning like a ticking-time-bomb on the bedside table. It may look like it came in the mail from ACME, but all that went into this is some wooden dowels covered in craft paper and an Arduino-compatible board. The 7-segment display can act as a clock, or count down to your doom. You can set an alarm that requires you to clip the wires to shut it off. Each time that alarm is set the wires are randomly chosen; one will set of the bomb, one will safely defuse it, and the others do nothing. See for yourself after the break.

The wires are easily replaced because they are connected via terminal blocks. It still seems like an awful waste of wire. We like the Think Geek bomb clock concept that works in much the same way but uses wires that have a male/female RCA plug pair that can be disconnected and reconnected without waste.

This one will apparently be available as a kit, at which point the schematics and code will be released. But it shouldn’t be too hard to build one from scratch yourself, and it’s an obvious winner if you’ve got kids.

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Booby box – It’s a trap!

Here’s a puzzle oddity that challenges you to open the box without falling into one of the booby-traps. It was built as a side-distraction from the more serious events happening at Insomni’hack 2011. [Sergio] and a colleague built the box to resemble a ticking bomb like in the blockbuster action movies we know you look forward to seeing each summer. A display on top of the device counts down for ninety seconds with an audible beep to mark the passage of time and boost your tension level. See it ticking away in the clip after the break.

Two wires meet at the edges of the box halves, completing a circuit that will set off an alarm when the contact is broken. There’s also a photocell on the bottom of the box which triggers the alarm if you lift it and expose this sensor to light. The combination necessary to open the box was provided to each competitor; it was not a numerical code, but a color code. Three potentiometers control the red, green, and blue anodes of an RGB LED, while being monitored by an Arduino at the same time. If you can dial in the appropriate color, the lid trap is disabled and the box can be opened. What does the winner get? Why an Arduino, of course!

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