Light Emitting Logic Gates Built From Scratch

What’s the weirdest computer you can think of? This one’s weirder.

[Dr. Cockroach] figured out a way to create an inverting NOT gate from just one LED and two resistors (one being a photo-resistor). The Dr. has since built AND, NAND, OR, NOR, XOR and XNOR gates, as well as …read more

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Glimmies, as logic

[Jacob Christ] writes in with a hack that’s going to be this summer’s fidget spinner. Why? The favourite toy of his youngster’s generation is a Glimmie. And while fidget spinners were useful for, well, spinning, the small animal-like Glimmie seems to have an unexpected property, they can function as logic gates.

They form an optical inverter, in their head is a phototransistor and in their belly an LED which goes on when the head is in the dark. He’s found through experimentation that they can be combined to form an AND gate, and thus a NAND gate with the addition …read more

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Living Logic: Biological Circuits for the Electrically Minded

Did you know you can build fundamental circuits using biological methods? These aren’t your average circuits, but they work just like common electrical components. We talk alot about normal silicon and copper circuits ‘roud here, but it’s time to get our hands wet and see what we can do with the power of life!

In 1703, Gottfried Wilhelm Leibniz published his Explication de l’Arithmétique Binaire (translated). Inspired by the I Ching, an ancient Chinese classic, Leibniz established that the principles of arithmetic and logic could be combined and represented by just 1s and 0s. Two hundred years later in …read more

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Relay Computing

Recently, [Manuel] did a post on making logic gates out of anything. He mentioned a site about relay logic. While it is true that you can build logic gates using switch logic (that is, two switches in series are an AND gate and two in parallel are an OR gate), it isn’t the only way. If you are wiring a large circuit, there’s some benefit to having regular modules. A lot of computers based on discrete switching elements worked this way: you had a PCB that contained some number of a basic gate (say, a two input NAND gate) and …read more

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Yes, You Can Reverse Engineer this 74181

[Ken Shirriff] is the gift that keeps on giving this new year. His latest is a reverse engineering of the 74181 Algorithmic Logic Unit (ALU). The great news is that the die image and complexity are both optimized for you to succeed at doing your own reverse engineering.

We have most recently seen [Ken] at work explaining his decapping and reverse engineering process at the Hackaday SuperCon followed soon after by his work on the 8008. That chip is crazy with complexity and a die-ogling noob (like several of us on the Hackaday crew) stands no chance of doing more …read more

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Fallout 4 Gets Logic Gates, Is Functionally Complete

Fallout 4, the latest tale of post-apocalyptic tale of wasteland wanderers, got its latest DLC yesterday. This add-on, Contraptions Workshop, adds new objects and parts to Fallout 4‘s settlement-building workshop mechanic. This add-on brings more building pieces, elevators, and most importantly logic gates to Commonwealth settlements.

The Fallout logic gates are used in conjunction with electric generators, lights, and automated sentries used to build settlements. Although a simple NAND would do, there are several types of logic gates including AND, OR, XOR, NOT, NAND, NOR, and XNOR.

The in-game explanation for these gates is very, very weird. AND, …read more

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Designing Circuits with Switching Algebra

We return once again to the work of Dr. Claude E. Shannon, this time to his Masters thesis on relay switching circuit design. This thesis introduced switching algebra that allows the systematic design and optimization of logical circuits. While Shannon’s work applied to switches and relays, it is equally applicable to all the modern forms of digital circuits. His thesis received widespread notice when published as “A Symbolic Analysis of Relay and Switching Circuits” in 1938. This work built on the Boolean algebra developed by George Boole and an analysis of logic by Augustus De Morgan which these mathematicians published …read more

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