Tiny Morse Code Trainer

June 23, 2011 by Brian Benchoff 18 Comments

[Eric] wanted to teach his kids Morse code, so he built a tiny Morse code trainer.

[Eric] built the trainer around an ATtiny85, and the rest of the circuit follows this minimalist idea. After connecting a piezo beeper and 6-pin ISP header, the only thing left to do was write a little code and start teaching his kids Morse. The Morse trainer is programmed to repeat the message, “SOS the moon rover has broken down and I am stuck in the trash can in the garden shed,” [Eric] planted a Lego moon rover in his shed as a prize for learning Morse, making him one of the coolest dads ever.

Although learning Morse isn’t required for an amateur radio license anymore, it’s a requirement for continuous wave radio. We think this is a great way to learn Morse the right way – actually hearing the characters – instead of memorizing the Huffman tree of Morse characters.

Modding A Car Charger To A Variable Power Supply

June 19, 2011 by Brian Benchoff 11 Comments

For an upcoming road trip, [Patrick] needed a small variable power supply. Instead of lugging around a bench supply, [Patrick] did the sensible thing and reverse engineered a cell phone charger to fit his requirements.

After cracking open an old Kyocera car charger, [Patrick] found a small PCB with completely labeled, all through-hole components – excellent reverse engineering potential. After finding an On Semi MC33063 IC, [Patrick] tore through the datasheets, generated a netlist, and developed a schematic that closely resembled the reference schematic given by the datasheets.

With all the grunt work done, [Patrick] set out to finish what he started – modifying the charger to output 3-10 Volts. After replacing a resistor with a 5k multiturn pot, [Patrick] was left with a power supply with a variable output from 2.8 to 8.8 Volts. Not exactly what was desired, but more than enough for the application at hand. While this hack isn’t a disco floor, it’s a great walkthough of the hacking process – building or modifying something to suit a need.

Homebrew TTL Logic Computer

June 17, 2011 by Brian Benchoff 48 Comments

Although [Jack] just graduated High School and doesn’t have much experience with electronics, that didn’t stop him from building the DUO Adept, a homebrew computer built entirely out of TTL logic chips.

The DUO Adept has 64k of memory, 6K of which is dedicated to the video ram that outputs a 240×208 black and white image onto a TV. Bootstrapping the computer to it’s current state was quite a challenge, as an entire OS was put into th system one bit at a time though DIP switches. After the OS was written to the computer, [Jack] was able to connect a keyboard and started programming. [Jack] programmed a hex editor and a few games of his own design. If all that wasn’t impressive enough, [Jack] also programmed an assembly compiler and emulator for his homebrew system.

We’ve seen a a few homebrew computersbefore, but not many of them are laid out on 17 breadboards like the DUO Adept. With skills like these, we can’t wait to see what [Jack] comes up with next. Check out the video after the break for a walk-through of the build.

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An Even Simpler Smartphone Garage Door Opener

June 15, 2011 by Nick Schulze 39 Comments

We have seen smartphone garage door openers in the past, but [Lou’s] Hack is beautiful in its simplicity. His door opener tackles the problem without using computers, Arduinos, wireless modules or even any smartphone based applications. For this project all that is needed is a Bluetooth headset and a single transistor. The door opener uses the Samsung HM1100 Bluetooth headset, which [Lou] has done significant testing on to show that his creation is quite secure and will not open the door unexpectedly.

When this headset connects to a phone it produces a beep from the earbud, so [Lou] removed the speaker and replaced it with a transistor. Now he can use the voltage spike produced by the amplifier before the beep as his switching signal. By wiring the transistor in parallel with the door button inside his garage he is able to open the door wirelessly by connecting then right away disconnecting from the headset. This setup is apparently perfectly secure as the only way to initially link your phone with the headset is to be inside the garage. Check out the video after the break for build instructions and a demonstration.

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Turning Beer Cans Into Bells With 35kV

June 14, 2011 by Brian Benchoff 9 Comments

It looks like we now have another way to annoy ourselves with extremely high voltage.

The bells operate under the same principles as the electrostatic see-saw we covered last month. A voltage is applied to one can while the other can is grounded. An insulated pendulum is placed between each can, and with a little coaxing can be made to oscillate back and forth between the cans. As the pendulum touches the charged can, it is repelled as it gains the charge and moves to the grounded can. There, the charge is released and the cycle continues again. A homemade Cockcroft Walton multiplier is used to generate the +35kV needed to get the pendulum moving.

[Ben Franklin] invented the Franklin Bells while he was investigating electricity in the 1750s. Originally an extension of the kite & key experiment, the bells were historically used to warn of approaching thunderstorms – when the bells rang, the atmosphere was charged and lightning could strike. Even though the voltage between the bells is huge, very little current is drawn – the Oxford Electric Bells have been ringing since 1840 using the same electrostatic battery.

Displaying Graphics On An Oscilloscope

June 10, 2011 by Brian Benchoff 6 Comments

[Andrew Rossignol] was curious one day and decided that he wanted to display graphics on an oscilloscope after playing around with the X and Y inputs.

[Andrew] started out with a resistor ladder on the DAC of his AVR Butterfly. He was able to to draw a line on the oscilloscope’s screen but bandwidth limitations forced him to reconsider his approach. A friend wrote a Python script to generate C code so the ports of the Butterfly can be toggled. After getting the Butterfly to generate a voltage for every non-white pixel, [Andrew] was impressed with the results so the code was modified determine the brightness of each pixel. The setup managed 10 shades of gray and careful selection of what graphics to post on the build log assured the project a little bit of blog cred.

There are a few ways to display a picture on an oscilloscope, like plugging the Hsync and Vsync into the inputs of a scope. Except for a few music visualizations, we haven’t seen a scope display generated from a microcontroller. Great work [Andrew], but we’d like to mention there’s a grayscale Hack a Day logo from way back when.

Check out a video of [Andrew]’s oscilloscope after the break.

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Gigantic Ball-manipulating Binary Computer

June 9, 2011 by Brian Benchoff 23 Comments

The folks at Evil Mad Scientist Labs just put up a post on the giant mechanical binary computer they brought to last month’s Maker Faire.

As a faithful reproduction of the Digi-Comp II from the 1960s, every operation is powered by balls falling onto levers. Unlike the original, the larger version is powered by billiard balls instead of half-inch marbles. The Digi-Comp II is able to count, add, subtract, multiply, divide, get the 1s or 2s complement and zero all of it’s bits. With a 7-bit accumulator, the Digi-Comp II is able to calculate anything where the result is less than 127, so we wouldn’t recommend doing your taxes on it. In the demo video, it took the Digi-Comp II about two minutes and twenty seconds to multiply 3 by 13. We’re not going to venture a guess on the equivalent seconds per cycle for an electronic calculator, but it’s an impressive build

The Digi-Comp II is a great way to show the process of binary arithmetic in a computer and we were wondering why there aren’t any educational toys like the Digi-Comp II out today. A site linked from the build page tells us there will be kits available this summer, we’re hoping the kit doesn’t fill the bed of a pickup truck.

Check out the video after the break for the multiplication demo.

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