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 1907, Lee De Forest’s “Audion” is used as an AND gate. Forty years later in 1947, Brattain and H. R. Moore demonstrate their “PNP point-contact germanium transistor” in Bell Labs (often given as the birth date of the transistor). Six years later in 1953, the world’s first transistor computer was created by the University of Manchester. Today, 13,086,801,423,016,741,282,5001 transistors have built a world of progressing connectivity, automation and analysis.

While we will never know how Fu Hsi, Leibniz, Forest or Moore felt as they lay the foundation of the digital world we know today, we’re not completely out of luck: we’re in the midst’s of our own growing revolution, but this one’s centered around biotechnology. In 1961, Jacob and Monod discovered the lac system: a biological analog to the PNP transistor presented in Bell Labs fourteen years earlier. In 2000, Gardner, Cantor, and Collins created a genetic toggle switch controlled by heat and a synthetic fluid bio-analog2. Today, AND, OR, NOR, NAND, and XOR gates (among others) have been successfully demonstrated in academic labs around the world.

But wait a moment. Revolution you say? Electrical transistors went from invention to computers in 6 years, and biological transistors went from invention to toggle button in 40? I’m going to get to the challenges facing biological circuits in time, but suffice it to say that working with living things that want to be fed and (seem to) like to die comes with its own set of challenges that aren’t relevant when working with inanimate and uncaring transistors. But, in the spirit of hacking, let’s dive right in. Continue reading “Living Logic: Biological Circuits for the Electrically Minded”

Paper Circuit Does Binary Math with Compressed Air

Most of us can do simple math in our heads, but some people just can’t seem to add two numbers between 0 and 3 without using paper, like [Aliaksei Zholner] does with his fluidic adder circuit built completely of paper.

Pneumatic AND gate

There’s some good detail in [Aliaksei]’s translated post on the “Only Paper” forum, a Russian site devoted to incredibly detailed models created entirely from paper. [Aliaksei] starts with the basic building blocks of logic circuits, the AND and OR gates. Outputs are determined by the position of double-headed pistons in chambers, with output states indicated by pistons that raise a flag when pressurized. The adder looks complicated, but it really is just a half-adder and full-adder piped together in exactly the same way it would be wired up with CMOS or TTL gates. The video below shows it in action.

If [Aliaksei]’s name seems familiar, it’s because we’ve featured his paper creations before, including this working organ and a tiny working single cylinder engine. We’re pleased with his foray into the digital world, and we’re looking forward to whatever is next.

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Hackaday Prize Entry: Hot Logic

A few weeks ago, [Yann] was dumpster diving and found something of interest. Two vacuum tubes, an ECC83S and an EL84. This was obviously the droppings of a local guitarist, but [Yann] wanted to know if he could build something useful out of them. An amplifier is far too pedestrian, so he settled on a vacuum tube computer.

The normal pentodes and triodes you’ll find in a tube amp require a lot of support components like output transformers, tube sockets, and high voltage power supplies. This was a little too complicated for a tube computer, but after a little bit of searching, [Yann] found a better option for his MINIVAC — subminiature vacuum tubes. These require fewer support components, and can be found for very reasonable prices through the usual component suppliers. His entry for this year’s Hackaday Prize is Hot Logic. It’s a computer — or at least computer components — built out of these tubes.

The tubes in question are a few 1Ж29Б-В and 6Н21Б tubes, a vacuum pentode and dual triode, respectively. Add in a few diodes, and that meets the requirements for being sufficient to build a computer. As a neat little bonus, these tubes have requirements that are very easy to meet. The filament on the 1Ж29Б-В tube only needs 1.2 Volts.

These subminiature tubes are a little underappreciated in the world of audiophililia and DIY electronics. That’s a bit of a shame; these tubes are the most technologically advanced vacuum-based technology ever created. They were the heart and the brains of ballistic missiles, and if you look hard enough you source hundreds of them at very reasonable prices. A vacuum tube computer requires a lot of tubes, and if anyone will be able to build a vacuum tube computer it’s going to be [Yann] and his pile of Soviet surplus.

Relay Computer Starts with an Adder that Makes a Racket

Computers built using discrete logic chips? Seen it. Computers from individual transistors? Impressive, but it’s been done. A computer built out of electromechanical relays? Bring on the ozone!

The aptly named [Clickity Clack]’s new YouTube channel promises to be very interesting if he can actually pull off a working computer using nothing but relays. But even if he doesn’t get beyond the three videos in the playlist already, the channel is definitely worth checking out. We’ve never seen a simpler, clearer explanation of binary logic, and [Clickity Clack]’s relay version of the basic logic gates is a great introduction to the concepts.

Using custom PCBs hosting banks of DPDT relays, he progresses from the basic AND and XOR gates to half adders and full adders, explaining how carry in and carry out works. Everything is modular, so four of his 4-bit adder cards eventually get together to form a 16-bit adder, which we assume will be used to build out a very noisy yet entertaining ALU. We’re looking forward to that and relay implementations of the flip-flops and other elements he’ll need for a full computer.

And pay no mind to our earlier dismissal of non-traditional computer projects. It’s worth checking out this discrete 7400 logic computer and this all-transistor build. They’re impressive too in their own way, if a bit quieter than [Clickety Clack]’s project.

Continue reading “Relay Computer Starts with an Adder that Makes a Racket”

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 then the logic was all in how you wired them together. And in this context, the SPDT relay was used as a two input multiplexer (or mux).

In case you think the relay should be relegated to the historical curiosity bin, you should know there are still applications where they are the best tool for the job. If you’re not convinced by normal macroscopic relays, there is some work going on to make microscopic relays in ICs. And even if they don’t use relays to do it, some FPGAs use mux-based logic inside.  So it’s worth your time to dig into the past and see how simply switching between two connections can make a computer.

Mux Mania

How do you go from a two input mux to an arbitrary logic gate? Simple, if you paid attention to the banner image. (Or try it interactive). The mux symbols show the inputs to the left, the output to the right and the select input at the bottom. If the select is zero, the “0” input becomes the output. If the select is one, the “1” input routes to the output.

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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 Arithmetic 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.

74181-openedWe 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 than simply following along with what he explains. This time around, the 74181 is just right for the curious but not obsessed. Don’t believe me? The 8008 had around 3,500 transistors while the friendly 74181 hosts just 170. We like those odds!

A quick crash course in visually recognizing transistors will have you off to the races. [Ken] also provides reference for more complex devices. But where he really saves the day is in his schematic analysis. See, the traditional ‘textbook’ logic designs have been made faster in this chip and going through his explanation will get you back on track to follow the method behind the die’s madness.

[Ken] took his own photograph of the die. You can see the donor chip above which had its ceramic enclosure shattered with a brisk tap from a sharp chisel.

Make Logic Gates out of (Almost) Anything

Logic gates are the bricks and mortar of digital electronics, implementing a logical operation on one or more binary inputs to produce a single output. These operations are what make all computations possible in every device you own, whether it is your cell phone, computer, gaming console etc.  There are myriad ways of implementing logic gates; mechanically, electronically, virtually (think Minecraft), etc. Let’s take a look at what it takes to create some fun, out-of-the-ordinary gate implementations.

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