Honda Ignition Coils Sing The Song Of Their People

High-voltage experimenters have been using automotive ignition coils to generate impressive sparks in the home lab for decades, and why not? They’re cheap, easily obtainable, and at the end of the day, producing sparks is literally what they’re designed to do. But that doesn’t mean there isn’t room for improvement.

In his latest Plasma Channel video [Jay Bowles] revisits this classic experiment, bringing to bear the considerable high-voltage experience he’s gained over the last several years. Building on an earlier setup that used a single Honda ignition coil, this new dual-coil version can produce up to 60,000 volts and is driven by a cleaner and more reliable circuit based on the iconic 555 timer. A pair of potentiometers on the front of the driver can adjust its square wave output from 1 to 10 kilohertz manually, while a commercial Bluetooth audio receiver tied into the 555 circuit allows the output to be modulated by simply playing audio from a paired device.

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Custom Christmas Light Controller Blocks Blinks

Finding that his recently purchased LED Christmas lights defaulted to an annoying blinking pattern that took a ridiculous seven button presses to disable each time they were powered up, [Matthew Millman] decided to build a new power supply that keeps things nice and simple. In his words, the goal was to enable “all lights on, no blinking or patterns of any sort”.

Connecting the existing power supply to his oscilloscope, [Matthew] found the stock “steady on” setting was a 72 VAC peak-to-peak square wave at about 500 Hz. To recreate this, he essentially needed to find a 36 VDC power supply and swap the polarity back and forth at the same frequency. In the end the closest thing he could find in the parts bin was a HP printer power supply that put out 30 volts, so the lights aren’t quite as bright as they were before, but at least they aren’t blinking.

To turn that into a pair of AC square waves, the power supply is connected to a common L298 H-Bridge module. You might expect a microcontroller to show up at this point, but [Matthew] went old school, and created his two alternating 500 Hz square waves with a 555 timer and a 74HC74D dual flip-flop.

Unfortunately, he didn’t have the time to get a custom PCB made before Santa’s big night. Though as he points out, since legitimate L298s are backordered well into next year anyway, having the board in hand wouldn’t have helped much. The end result is that the circuit has to live on a breadboard for the current holiday season, but hopefully around this time next year we’ll get a chance to see the final product.

All Hail Your New Giant 555 Timer Overlord

You asked for it, and now you’ve got it. It’s taken more than a decade of accumulated complaining, but this gigantic 555 timer IC has finally gathered enough psychokinetic energy to take corporeal form and demand fealty from the readers of Hackaday.

Or not. The less exciting explanation is that creator [Rudraksha Vegad] was looking for a way to combine his interests in discrete electronic components and woodworking. The result is an incredible build that’s more than just a conversation starter; this desktop-sized version of the iconic integrated timer circuit is fully functional. You can even hook it up to a breadboard, assuming you’ve got some alligator clips handy.

Lifting the lid on this wooden “chip” uncovers an intricate hand-wired array of discrete components that stand in for the microscopic goings on inside the real thing. He’s even gone through the trouble of recreating the symbols for the comparators and flip-flops that you’d see in a diagram of a 555 using wooden shapes to elevate their respective components. It might not fit the classical definition, but surely this must count as some form of circuit sculpture.

[Rudraksha] credits several other projects for not just inspiring him to create his own mega 555, but for helping him wrap his head around the internal workings of everyone’s favorite IC. Using components he salvaged from old hardware, he says the project ended up being very educational for him. These days, when most makers are more likely to reach for a microcontroller than a logic chip, spending some quality time with transistors and passives can be quite illuminating.

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Implementing A CPU Using 555 Timers And Logic Synthesis

There is many a comment on these here pages along the lines of “Why did you use a microcontroller, when you could just have easily used a 555 timer!” And, yes, we sometimes agree with the sentiment, but when a chance comment seen by user [Tim Böscke] suggested turning it around and building a microcontroller out of 555 timers, the gauntlet was well and truly thrown down. Now let’s be clear, this is not the first time we’ve come across this idea, there was a breadboard 555 based build ten years ago, but this is the first time we’ve seen it done by leveraging open source synthesis targeting a PCB!

The first logic element was a simple inverter, constructed by tying the TRIGger and THReShold pins together.

LTSpice model of a NAND gate implemented with 555 and diodes

From there it was a simple matter of adding a few diode-resistor networks to the input, to effect a NAND2 gate and a NOR2 gate. Development was speeded up a bit by modeling the logic circuits in LTSpice, to find the best combination of part values. From these simple elements, all further logic functions could be implemented. Next a memory element was needed. As luck would have it, the 555 has a RS flip flop as part of its circuit, fed by dual comparator inputs. All that was needed was to bias the THRS input at Vdd/2 and then feed the data in via a pass transistor, and hey presto! a serviceable, albeit slow latch.

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You Can Always Use An ATtiny Instead Of A 555

It’s a constant of writing for Hackaday, that whenever a project appears using a 555 timer, someone will say “You could have used a microcontroller to do that!”. It’s something that [Shranav Palakurthi] has approached with the ATTiny555, a project that emulates an entire 555 by making clever use of the humble and ubiquitous microcontroller chip. We’ve all been guilty of it at some time, but now at last the ATTiny85 enthusiasts have conclusive proof that their favourite piece of cheap silicon can prove its mettle.

The full details of the ingenious 555 replacement can be found in its GitHub repository, and for those willing to take the plunge it’s as simple as adding a resistor and updating the firmware. It’s not the perfect 555 replacement with its imperfect analogue performance and swapped reset and ground pins, but it does however bring the advantage of a lower supply voltage.

You can see the device in action in the YouTube video below the break, but meanwhile rejoice that finally there’s a way to replace all those unnecessary 555s with your favourite inexpensive 8-pin chip!

While we’re on the subject of the 555, don’t forget we’re running our 555 contest again.

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Christmas tree PCB with Blinky Circuit

Is It Finally Time For Christmas Decorations?

[Arnov] is trying to get into the holiday spirit and is doing so the way he knows how. He was thinking of some cool decorations for his Christmas tree and decided the best decorations are the ones you make yourself, so he made his own blinky Christmas tree ornament.

The famed “blinky circuit” is certainly one that we are no strangers to here at Hackaday. Some of our readers will be very pleased to see that he did in fact use a 555 timer and not an Arduino. The 555 timer is wired to drive the clock pin of the CD4017 decade counter and the outputs of the decade counter are wired to the LEDs. The LEDs are lit up sequentially upon each low to high transition of the clock pulse though you may try getting creative with your LED wiring scheme to achieve different blinking effects.

What readers might really take away from this build is [Arnov] detailing how to import images into his CAD tool of choice, OrCAD in his case. We know that can be a bit tricky sometimes. Finally, we love that this project doubles as PCB art and a soldering challenge. It would definitely make for a good demo project at your next beginner soldering workshop.

Cool project [Arnov!]

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Treasure Hunting With A Handful Of Common Components

Sometimes simpler is better — when you don’t need the the computational power of an onboard microcontroller, it’s often best to rely on a simple circuit to get the job done. With cheap Raspberry Pis and ESP32s all over the place, it can be easy to forget that many simpler projects can be completed without a single line of code (and with the ongoing chip shortage, it may be more important now than ever to remember that).

[mircemk] had the right idea when he built his simple induction-balance metal detector. It uses a couple of 555 timers, transistors, and passives to sense the presence of metallic objects via a coil of wire. He was able to detect a coin up to 15 cm away, and larger objects at 60cm — not bad for a pile of components you probably have in your bench’s spare parts drawer right now! The detector selectivity can be tuned by a couple of potentiometers, and in true metal detector fashion, it has a buzzer to loudly blare at you once it’s found something (along with a LED, in case the buzzer gets too annoying).

All in all, this metal detector looks like a terribly fun project — one perfectly suited to beginners and more seasoned hackers alike. It serves as a great reminder that not every project needs WiFi or an OLED display to be useful, but don’t let that stop you from overdoing things! If touchscreens are more your speed, [mircemk] has got you covered with a smartphone-integrated version as well.

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