2023 Halloween Hackfest: Flickering Pumpkin Pin Is Solidly Built

October 4, 2023 by Kristina Panos 9 Comments

Now first of all, [Steph] grants that you can already take your pick of several LED pumpkin badges out there on IO. That’s not the point. The point is that this flickering pumpkin pin is nicely-built as well as being open source.

Even though it’s fully featured — it flickers, it’s wearable, and it’s lightweight — the build couldn’t be more simple. It’s fancy through-hole LEDs and a coin cell holder, plus a tack pin to stick it through your shirt. But the final result is quite elegant thanks to clever use of PCB layering.

The first version was to get all the layers right to let the light through and embellish the jack-o-lantern’s lines with manufacturer-applied silver solder, but as [Steph] points out, it looked ‘like something a disturbed child might carve into their desk in detention’. So [Steph] enlisted [Mx. Jack Nelson], who improved the artwork.

Pretty much every component does double duty here, including the tack pin — it serves as a switch because it can hold the battery in place. The battery’s edges reflect the glowing light quite nicely around the edge of the pin. And the LEDs beneath the battery prevent it from slipping out. You can see how it goes together in the video after the break.

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Bringing The Quake Flicker To Life With A Hacked Light

September 21, 2021 by Tom Nardi 14 Comments

If you ever feel a pang of shame because you’ve been reusing the same snippets of code in your projects for years, don’t. Even the big names do it, as evidenced by the fact that code written to govern flickering lights back in 1996 for Quake is still being used in AAA titles like 2020’s Half-Life: Alyx. In honor of this iconic example of digital buck-passing, [Rodrigo Feliciano] thought he’d port the code in question over to the Arduino and recreate the effect in real-life.

Since the Quake engine has been released under the GPLv2, it’s easy to pull up the relevant section of the code to see how the lighting was configured. Interestingly, lighting patterns were implemented as strings, where the letters from a to z referenced how bright the light should appear. So for example, a strobe light that goes between minimum and maximum brightness would be written as “aaaaaaaazzzzzzzz”, while a flickering light could be represented with the string “nmonqnmomnmomomno“.

An emergency light provided the LEDs and enclosure.

This ended up being very easy to implement on the Arduino in just a few lines, as [Rodrigo] simply had to assign each letter in the string a numerical value between 0 and 255 using map, and then use the resulting number to set the LED brightness with analogWrite.

With the code written, [Rodrigo] then had to put the hardware together. He stripped down a basic emergency light to get an array of white LEDs and a handy enclosure. He also wired up a simple transistor circuit on a scrap of perfboard so the Arduino Pro Mini could control all the LEDs from a single GPIO pin. Combined with a long USB cable to power it, and he’s got a perfect desk accessory for late-night gaming sessions.

In the video below you can see the final result, which [Rodrigo] has even synced up to footage from the classic 1996 shooter. The light makes for an interesting conversation piece, but we think the logical next step is to work this technique into an ambilight-like system to really make it feel like you’re wandering down those dimly lit corridors.

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Flickering LED Circuit

October 30, 2008 by Nick Caiello 16 Comments

Here’s a simple project for your Halloween celebration. The other day while looking through our box of Halloween decorations, we noticed that the incandescent lamp in one of the jack-o’-lanterns was burnt out. Instead of simply replacing the outdated bulb, we decided to build a small dark detecting circuit with 2 yellow LEDs based on this Evil Mad Scientist Laboratories design. After successfully building the circuit, we took the project one step further by incorporating an Atmel ATtiny13 microcontroller. The code switches the LEDs on and off randomly for a flickering effect and is based on this instructable. Below is the schematic we created in EAGLE and a parts list.

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