Left: the traces of a flashy paper Christmas tree. Right: the finished tree on cardstock.

Flashy Paper Christmas Tree Does It With A 555

December 13, 2024 by Kristina Panos 10 Comments

‘Tis the season for holiday hacks, and [Ben Emmett] is here to remind us that we don’t necessarily need a fancy microcontroller in order to make flashy fun things happen.

Smoothing down the copper traces with a guitar pick.

Take this Christmas tree for example, which uses a 555 timer and a CB4017 decade counter in order to drive some blinking LEDs. The ICs are through-hole, making the circuit fairly accessible to new players, but there are a few SMD components that need soldering as well. (More on that later.)

Here, the 555 acts like a clock and drives a square wave. Using the clock as input, the decade counter toggles the output pins one after the other, driving the LEDs to blink in turn. Since there are only eight lights, there is a pause in the light-up pattern, but that could be fixed by wiring decade counter output #9 to the reset pin.

Although function was the main focus circuit-wise, [Ben] managed to lay the traces in the shape of a Christmas tree, which looks great. Having done a similar project in the past, he discovered that the craft cutting machine prefers thick traces and wider spaces between them. This is largely why [Ben] chose to use through-hole ICs.

After laying everything out in KiCad, [Ben] exported the copper layer image for use on the cutting machine. Once it was all cut out, he put it on transfer tape to weed out the extra copper, and get the traces onto cardstock, the final substrate.

This is such a fun project, and we love that the CR2032 that powers it also acts as the stand in its vertical holder. Hit up GitHub if you want to make one for yourself. Want something even more 3D? Check out this hollow tree we saw a few years ago.

Using The 555 For Everything

October 14, 2024 by Bryan Cockfield 26 Comments

The 555 timer is one of the most versatile integrated circuits available. It can generate PWM signals, tones, and single-shot pulses. You can even put one in a bi-stable mode similar to a flip flop. All of these modes are available by only changing a few components outside of the IC itself. It’s also dirt cheap, so it finds its way into all kinds of applications its original inventors never imagined. There’s a bit of a trope around here as well that you ought not to use a microcontroller when one of these will do, and while it’s a bit of a played-out comment, it’s often more true than it seems. This video shows a few uncommon ways of using these circuits instead of putting a microcontroller to work.

After a brief overview of the internals of the hallowed 555, [Doctor Volt] walks us through some of its uses, starting with applications for digital inputs, including a debounce circuit and a toggle switch. From there, he moves on to demonstrating a circuit that can protect batteries from deep discharge, and a small change to that circuit can turn the 555 into a resetting fuse that can protect against short circuit events. Finally, the PWM capabilities of this small integrated circuit are put to work as an audio amplifier, although perhaps not one that would pass muster for the most devout audiophiles among us.

Even though it’s possible to offload a lot of the capabilities of a 555 onto a microcontroller, there’s certainly an opportunity to offload some things to the 555, even if your project still needs a microcontroller. However, offloading tasks like debounce or input latching to hardware rather than spending microcontroller cycles or pins can make a project more robust, both from reliability and software points of view. For some other useful circuits, some of which have been forgotten in the modern microcontroller age, it’s worth taking a look at some of these antique circuit books as well. While we are sure the 555 designers hoped it would be a big hit, no one imagined this giant one.

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Building An Automotive Load Dump Tester

October 13, 2024 by Dave Rowntree 11 Comments

For those who have not dealt with the automotive side of electronics before, it comes as somewhat of a shock when you find out just how much extra you have to think about and how tough the testing and acceptance standards are. One particular test requirement is known as the “load dump” test. [Tim Williams] needed to build a device (first article of three) to apply such test conditions and wanted to do it as an exercise using scrap and spares. Following is a proper demonstration of follow-through from an analytical look at the testing specs to some interesting hand construction.

The load dump test simulates the effect of a spinning automotive alternator in a sudden no-load scenario, such as a loose battery terminal. The sudden reduction in load (since the battery no longer takes charging current) coupled with the inductance of the alternator windings causes a sudden huge voltage spike. The automotive standard ISO 7637-2:2011 dictates how this pulse should be designed and what load the testing device must drive.

The first article covers the required pulse shape and two possible driving techniques. It then dives deep into a case study of the Linear Tech DC1950A load dump tester, which is a tricky circuit to understand, so [Tim] breaks it down into a spice model based around a virtual transistor driving an RC network to emulate the pulse shape and power characteristics and help pin down the specs of the parts needed. The second article deals with analysing and designing a hysteric controller based around a simple current regulator, which controls the current through a power inductor. Roughly speaking, this circuit operates a bit like a buck converter with a catch diode circulating current in a tank LC circuit. A sense resistor in the output path is used to feedback a voltage, which is then used to control the driving pulses to the power MOSFET stage. [Tim] does a good job modeling and explaining some of the details that need to be considered with such a circuit.

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Bringing The 555 Mini-Notebook To Video

July 10, 2024 by Alexander Rowsell 17 Comments

Like many of us [AnotherMaker] is a fan of the classic Forrest Mims electronics books, specifically, the Engineer’s Mini-Notebook series. They were great sources of inspiration, but at the time, he couldn’t afford to actually build most of the circuits described. Now as an adult, he decided to go through the 555 Timer IC Circuits Mini-Notebook, full of example circuits and explanations, all in Mims’ trademark handwritten style, and build all the circuits for real. And so, a series of YouTube videos are currently being released going over every circuit, how it works, and looking at waveforms on an oscilloscope!

So, PCBs were designed, each containing four of the circuits from the book. With the Mims circuit diagram on one side of the screen and the PCB on the other, [AnotherMaker] goes into a good amount of detail explaining how each circuit works, referring to the schematic and oscilloscope as needed. Each part in the series focuses on the next circuits in order, and eventually the whole series will cover every single circuit in the book.

It’s a great series of videos for anyone learning electronics, especially those who would like to learn about one of the most produced integrated circuits of all time! It’s also an excellent way to bring a fresh perspective to this classic book, while simultaneously bringing the content to a wider audience via online video.

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A treadmill with a doorbell alert in one of the cup holders.

See Them Knocking With A Doorbell Alert

June 21, 2024 by Kristina Panos 8 Comments

Picture it: you’re on the treadmill, running through a forest, sweating like a pig, and the doorbell rings because a package is being delivered. Would you even hear it? Chances are, if you’re rocking out to music on headphones and your treadmill is as noisy as [Antonio]’s, you wouldn’t, and you’d once again face the dreaded ‘we’ll try later’ slip.

What you need is something that thing listens for the doorbell and flashes a giant 20 mm red LED to alert you. Could this be done with a 555? Yes, in fact, [Antonio] used a pair of them in the form of the 556 on the alert side.

The first 555 is wired up in astable mode to control the tempo of the flashing light, and the second timer is in monostable mode to control the length of time the light flashes. Power comes from the doorbell’s 9V, which is wired up through an existing Ethernet jack.

Now whenever the doorbell rings, [Antonio] has 60 seconds of flashing light in order to react, stop the treadmill, and jump off to answer the door. To conserve power when [Antonio] is relaxing, there’s an on/off switch.

Homebrew Computer From The Ground Up

May 26, 2024 by Bryan Cockfield 12 Comments

Building a retro computer of some sort is a rite of passage for many of us, with some building replicas or restorations of old Commodores, Ataris, and other machines from decades past. Others go even further back, to the time of the Intel 8008 or earlier, and a dedicated few will build something completely novel. This project from [3DSage] falls squarely in the latter category, with his completely DIY computer built component by component from scratch, including the machine code needed to run it.

[3DSage] starts with the backbone of every computer: the clock. He first demonstrates how a pair of NOT gates with a set of capacitors can be used as a rudimentary clock pulse, then builds a more refined version with a 555 timer and potentiometer for adjustable rates. Then, it’s on to creating a binary counter, which is a fundamental part of the memory system for this small computer, and finally, allows this circuitry to behave like a normal computer. Using a set of switches to store values in memory and stepping through them with the clock, the computer can be programmed to do plenty of tasks just like a modern microcontroller.

[3DSage] built this project a few years ago and has used it for real-world applications such as controlling servos, LED arrays, playing music, and other tasks. Although he has to program it using his own machine code by hand, it’s a usable computer in many ways. If you want to eschew modernity and build a retro computer in the style of the 1960s, though, this piece goes through what it would have been like to build a similar system in the era when these computers were more common. If you have a switch fetish, you might like to see how real computers worked back then, too.

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Test Your Capacity For Circuit Sculpture With Flashing Lights

December 30, 2022 by Kristina Panos 15 Comments

Have you tried your hand at circuit sculpture yet? Well, if you were waiting for the ideal first project with a great build video to go along with it, keep reading. [4dcircuitry]’s 555-based flashing circuit sculpture ticks all the go-for-it boxen for us — the component list is short, the final circuit looks cool, and well, there are blinkenlights.

Of course, it’s not quite a zero-entry project. Although [4dcircuitry] makes it look oh-so easy build it in the video below, they are using 1206 components and an SOIC-packaged 555 timer here. On the other hand, they start by smartly laying everything out on double-stick tape before applying flux and soldering. Then when it’s time to run the wires that no one wants to see, [4dcircuitry] carefully tweezers it from the tape and flips it over, re-using the tape do solder up the back side.

Don’t have the patience to solder 1206? All component sizes are beautiful, as evidenced by this amazing circuit sculpture clock.

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