Turing Ring Is Compact

December 28, 2021 by Al Williams 2 Comments

One of the problems with a classic Turing machine is the tape must be infinitely long. [Mark’s] Turing Ring still doesn’t have an infinite tape, but it does make it circular to save space. That along with a very clever and capable UI makes this one of the most usable Turing machines we’ve seen. You can see a demo in the video below.

The device uses an Arduino Nano, a Neopixel ring, an encoder, and a laser-cut enclosure that looks great. The minimal UI has several modes and the video below takes you through all of them.

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Custom Christmas Light Controller Blocks Blinks

December 27, 2021 by Tom Nardi 8 Comments

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.

WS2812s On A 6502

December 23, 2021 by Elliot Williams 40 Comments

We can still remember when the WS2812 LED first came into our consciousness, way back in the mists of time. The timing diagrams in the datasheet-of-questionable-veracity made it sound quite tricky, with tight timing tolerances and essentially a high-speed two-bit PWM data protocol at 500 kHz. It was a challenge to bit-bang with an ATtiny85 back then, but there’s no way something as old and crusty as an Apple II would be up to snuff, right?

[Anders Nielsen] took up the challenge of getting the venerable 6502 processor to drive Neopixels and won! After all, if the chip is good enough for Bender and the Terminator T-800, it should be able to blink some colored LEDs, right? The secret sauce is shift registers!

Specifically, [Anders] abuses the 74LS165 parallel-in, serial-out shift register for his dirty work. Instead of bit-banging the WS2812’s “long high is a 1, short high is a 0” signal directly, the first few bits of the shift register are hard-wired to VCC and the last few to GND.

The bits in the middle determine if the pulse shifted out is long or short, and they’re set by the 6502, through a 6522 VIA chip, just like the Apple II would have. Clocking the data out of the shift register handles the timing-critical stuff. Very clever!

Video below the break.

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Kamehameha!! PCB Badge

December 19, 2021 by Orlando Hoilett 7 Comments

PCB Art has surely captivated us over the past few years and we’re ever intrigued with the intricate detail the community puts into their work. We’re no strangers to [Arnov]’s work and he has impressed, yet again, with his Kamehameha PCB badge.

Unfortunately, no 555 timer was used in the making of this project, but don’t let that turn you away. Instead, we have an ATtiny84 microcontroller for implementing the logic to control the LEDs, a MOSFET-based driver for driving current through the LEDs, and, of course, the LEDs to give the “turtle destruction wave” its devastating glow. Pay really close attention to the detail [Arnov] put into the silkscreen as you can see that’s a pretty crucial part of this build.

Aside from marveling at [Arnov]’s work, fans of the OrCAD PCB designing software will learn how to import an image file into their project as [Arnov] walks through that step in his tutorial. He even has some pretty good reflow soldering tips if you’re looking to try your hand at SMD soldering.

Another cool build [Arnov]. Keep it up!

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Ninja Art: PCB Nightlight Jutsu!

December 10, 2021 by Orlando Hoilett 3 Comments

This latest PCB artwork comes to you courtesy of [Arnov]. His Naruto nightlight is definitely going to get your anime-loving friends’ attention.

The LED illumination styles are controlled by an ATtiny13A microcontroller. He probably could have opted for a 555 timer with this one, but maybe he wanted easily programmable blinking patterns. He also programmed the ATtiny to read a small button which he used to cycle through different illumination styles. Finally, a small LiPo battery makes this project pretty portable, so you can reposition it freely around your work area as you might like.

With all that being said, the meat of this project is in the physical dimensional design of the PCB. [Arnov] was able to design the circuit board in the shape of Naruto’s head, with pretty good detail for his hair, eyes, and headband. If you’ve ever tried your own PCB art, you know that it can be a fairly onerous task. He creatively used the copper traces as features within the PCB, in this case, Naruto’s ninja headband. We thought the subtle decision of putting the LEDs on the backside of the PCB was smart as well. By doing so, he used the solder mask as a natural light defuser which really gave the PCB a cool, yellow glow. Carefully removing the copper layer and not using a copper pour really aided in the aesthetic. He was also smart to opt for yellow solder mask since Naruto’s hair is yellow.

All in all, two thumbs up [Arnov]. While you’re here, check out some other great PCB art around Hackaday.

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(Getting Rid Of) The Ghost In The LED

December 8, 2021 by Ryan Flowers 38 Comments

Multiplexing is a very old technology in which control signals are intermixed for the sake of being able to control more devices than there are control signals. For [mihai.cuciuc], the problems started when he multiplexed some very efficient LEDs.

The problem? In two banks of six LEDs each, both LEDs connected to a single Arduino pin would light, even when only one bank was turned on at the ground side. The LED In the bank that was switched on lit brightly, and its corresponding LED in the bank that was off would also be very dimly lit. [mihai] was able to determine that the problem was not due to a leaky transistor, but rather due to a quality of the LEDs themselves.

What is an LED but a diode, and it’s well known that diodes also have capacitance. In fact, this quality is exploited in varactor diodes, a specialty diode whose capacitance can be changed by varying the voltage on the cathode. [mihai] deduced that this capacitance was causing current to flow in the bank that was off. Where was the current going? From the Arduino pin that was on, through its attached LED, and then into the rest of the bank of LEDs, charging them like capacitors. [mihai] hasn’t seen this before, but theorizes that for the latest batch of high efficiency LEDs, this minute current is enough to light the LED through which the current is flowing.

[mihai]’s solution is an elegant hack which he’s made available for your perusal. You might also enjoy this introduction to diode basics by W2AEW. If you have any great diode or LED hacks of your own, be sure to drop us a line!

3D Printed Lithographic Moon Lamp

December 8, 2021 by Orlando Hoilett 16 Comments

After years of being a software developer, [Chris] was excited to get back into embedded development and we’re glad he did. His 3D printed lithographic moon lamp combines a number of hacker and maker skills, and is sure to impress.

3D-printed lithographic moons have gotten pretty popular these days, so he was able to find a suitable model on Thingiverse to start with. Gotta love open-source. Of course, he needed to make a few modifications to fit his end design. Namely, he put a hole at the bottom of the moon, so he could slide the LED and heatsink inside. The 3 watt LED is pretty beefy, so he definitely needed a heat sink to make sure everything stayed cool.

Otherwise, the circuit itself is pretty straightforward. He has an ESP32 to drive the RGB LED through a transistor, and fitted the components onto a custom-designed circuit board to ensure everything stayed neat and organized. You don’t want a ton of loose wires and breadboards cluttering this build. Since he used an ESP32, he was able to create a simple web interface to control the color of the LEDs. Gotta make it connected somehow, right?

What’s great is in addition to the project write-up, [Chris] includes video tutorials, walking the readers through each individual step of the build. By doing so he really makes it easy for readers to follow along and reuse his work. If you’re still looking for ideas, one of these could make a really good Christmas present.

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