Cheap and easy logic signal generator

While function generators or analog signal generators are ubiquitous in their utility, we haven’t seen much of logic function generators on Hack a Day. Luckily, [Dilshan] sent in a really neat 8-channel signal injector that is amazingly simple to build and comes with a great front end for editing patterns from your computer.

The hardware portion of the build is kept to a minimum with a PIC18F chip, USB socket, and header pins as the only major components. This board serves as the hardware output for the Kidogo software. This software provides a very nice interface to generate 5 volt logic signals on eight separate channels that will immensely help exploring your digital world.

With a great interface and very easy to build hardware, we can easily see the Kidogo hardware finding its way onto workbenches around the world. We’re tempted to build our own version using an AVR, but we would hate to ruin such a simple but useful tool.

Simple device answers questions just like your boss does


Like many of us, [Bertho] has had plenty if interaction with “Executive” types who seem to make decisions randomly, and most certainly not based upon any sort of reason. As he was picking through parts bins at his local hackerspace, he thought it would be fun to build an “Executive Decision Maker”. The device he had in mind would answer questions at the push of a button, with the kind of randomness that could only be carefully honed through years of barking orders from a corner office.

Constructed from third-rate LEDs and old CMOS chips that were lying around, the operation of the device is quite simple. Much like a Magic 8 Ball, a question is posed, and as [Bertho] states, “The Executive Decision maker automatically tunes into the aether and the subconscious of the user” pressing the “Decide” button. The device then makes a judgement, relaying its answer to the user via an LED display.

We definitely got a good laugh out of this one, so be sure to check out the video after the break to see the Executive Decision Maker in action.

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LED artwork disappears right before your eyes


If you walked into an art gallery and saw nothing but blank canvases lining the wall, you might be compelled to demand your money back, or assume that you had discovered the world’s laziest artist. If this gallery happened to be displaying work by [Brad Blucher and Kyle Clements] however, you would be mistaken.

These two artists have collaborated to create a series of works titled, “Take a Picture“. Each picture they have built is constructed to look like an empty canvas when viewed with the naked eye. If you were to take a picture of the canvas with your cell phone or digital camera however, a whole new world would open up in front of your eyes. Their artwork is constructed using infrared LEDs, which cannot be seen with the naked eye, but are visible to nearly any CMOS or CCD sensor on the market. The images range from simple smiley faces and objects to abstract geometric shapes.

It’s a very simple, yet novel approach, and we happen to think it’s pretty cool. The artists have not said what they have planned for this project in the future, but we’d love to see it expanded using larger LED arrays to display higher-resolution images, or even short movies.

Keep reading to see how they went about creating these works of art as well as a promo video demonstrating the effect.

Continue reading “LED artwork disappears right before your eyes”

Breadboarding RAM

If you’ve ever wanted to dive in and take a look at how memory hardware is implemented here is a good example of how to implement some latching circuits with ether BJT or CMOS transistors. BJTs require biasing resistors which increases the complexity and power consumption when compared to CMOS. If power consumption isn’t an issue you could certainly make some really fast logic.

Most modern on chip RAM is made using SRAM because it only takes six transistors to implement(vs eight) and is pretty fast. When it comes to density DRAM can get one bit of storage by using a single transistor and capacitor(putting the capacitor underneath he transistor can save even more space). All that said, latches and flip flops are still a very useful (and common) tool when working with digital circuits.

Intel 4004 internals


The silicon wizards at Flylogic have certainly posted an interesting chip this time around. The Intel 4004 was the first widely used microprocessor. The logic gates are much larger than you’d find in modern chips. The unique feature is that each gate is designed to make the most efficient use of the silicon instead of the standardized shapes you find now. They’ve uploaded a full image of the chip.

For an introduction to silicon hacking, we reccomend [bunnie]’s talk from Toorcon and [Karsten]’s talk from 24C3. You can find many more posts on the topic in our silicon tag.