Category Archives: relay

Hackaday Prize Entry: Pyrotechnics Sequencer with Wireless Control

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[visualkev]’s friend was putting on his own fireworks show by lighting each one in turn, then running away. It occurred to [visualkev] that his friend wasn’t really enjoying the show himself because he was ducking for cover instead of watching the fun. Plus, it was kind of dangerous. Accordingly, he applied his hacker skills to the challenge by creating a custom fireworks sequencer.

He used a custom PCB from OSH Park with an ATMega328P controlling eight TPIC6C595 8-bit shift registers, which in turn trip the 64 relays connecting to the fireworks. A 5V regulator supplies the project from 5 5AA …read more

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The Bane of Aftermarket Car Alarms

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The humble car alarm has been around almost as long as the car itself, first being developed by an unknown prisoner in Denver, circa 1913. To the security-conscious motorist, they make a lot of sense. The noise of a car alarm draws attention which is the last thing a would-be thief wants, and the in-built immobilizers generally stop the car being moved at all without a time-consuming workaround. Both are a great deterrent to theft.

It may then surprise you to know that I, dear readers, consider the aftermarket car alarm to be one of the most heinous devices ever …read more

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An Introduction to Solid State Relays

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When we think of relays, we tend to think of those big mechanical things that make a satisfying ‘click’ when activated. As nice as they are for relay-based computers, there are times when you don’t want to deal with noise or the unreliability of moving parts. This is where solid-state relays (SSRs) are worth considering. They switch faster, silently, without bouncing or arcing, last longer, and don’t contain a big inductor.

An SSR consists of two or three standard components packed into a module (you can even build one yourself). The first component is an optocoupler which isolates your control …read more

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Knitting ALUs (and Flipdots)

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[Irene Posch] is big into knitted circuits. And while most of the textile circuits that we’ve seen are content with simply conducting enough juice to light an LED, [Irene]’s sights are set on knittable arithmetic logic units (ALUs). While we usually think of transistors as the fundamental building-blocks of logic circuits, [Irene] has developed what is essentially a knit relay. Be sure to watch the video after the break to see it in construction and in action.

The basic construction is a coil of conductive thread that forms an electromagnet, and a magnetic bead suspended on an axle so that …read more

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Single Board Relay Computer

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We all know you can build a computer out of relays, and if you’re a regular reader of Hackaday, you’ve probably seen a few. Actually designing and fabricating a computer built around relays is another thing entirely, and an accomplishment that will put you right up there with the hardware greats.

The newest inductee of the DIY microcomputer hall of fame is [Jhallen]. He’s built a microcomputer ‘trainer’ out of relays. It’s got more click and clack than the Tappet family, and is a work of art rendered in DPDT relays.

The biggest consideration in designing a relay computer is …read more

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Relay Computer: You Can Hear It Think

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Modern digital computers have complex instruction sets that runs on state-of-the-art ALUs which in turn are a consequence of miniaturized logic gates that are built with tiny transistors. These tiny transistors are essentially switches. You could imagine replacing with electromagnetic relays, and get what is called a relay computer. If you can imagine it, someone’s done it. In this case, [jhallenworld].

The Z3 was the first working programmable, fully automatic digital computer designed by Konrad Zuse. The board employs modern semiconductor devices such as memory and microcontrollers, however, the CPU is all relays. A hexadecimal keyboard allows for program entry …read more

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Relay Computer: You Can Hear It Think

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Modern digital computers have complex instruction sets that runs on state-of-the-art ALUs which in turn are a consequence of miniaturized logic gates that are built with tiny transistors. These tiny transistors are essentially switches. You could imagine replacing with electromagnetic relays, and get what is called a relay computer. If you can imagine it, someone’s done it. In this case, [jhallenworld].

The Z3 was the first working programmable, fully automatic digital computer designed by Konrad Zuse. The board employs modern semiconductor devices such as memory and microcontrollers, however, the CPU is all relays. A hexadecimal keyboard allows for program entry …read more

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Switching: from Relays to Bipolar Junction Transistors

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How many remote controls do you have in your home? Don’t you wish all these things were better integrated somehow, or that you could add remote control functionality to a random device? It’s a common starting point for a project, and a good learning experience for beginners.

A common solution we’ve seen applied is to connect a relay in parallel to all the buttons we want to press. When the relay is triggered, for example by your choice of microcontroller, it gets treated as a button press. While it does work, relays are not really the ideal solution for the …read more

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Have Alexa Open Your Garage Door

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[yoyotechKnows] built an Alexa-controlled garage door opener after his Liftmaster stopped working. Now all he has to do is holler at his mobile phone and he can raise and lower his garage doors at will.

His project is based around a Photon WiFi kit, with a pair of LCC 120 digital relays triggering the two doors, reed switches, and a serial-equipped LCD to display door status, with Alexa, IFTTT, and OpenHab to process the commands. You can find his code in the project writeup.

Currently he has a LCD display informing him of the status of each door, hot glued …read more

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Fight Mold and Mildew with an IoT Bathroom Fan

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Delicious sheets of wallboard coated with yummy latex paints, all kept warm and moist by a daily deluge of showers and habitually forgetting to turn on the bathroom exhaust fan. You want mildew? Because that’s how you get mildew.

Fed up with the fuzzy little black spots on the ceiling, [Innovative Tom] decided to make bathroom ventilation a bit easier with this humidity-sensing IoT control for his bathroom exhaust fan. Truthfully, his build accomplishes little more than a $15 timer switch for the fan would, with one critical difference — it turns the fan on automatically when the DHT11 sensor …read more

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