A Nifty Tool For Counting Neopixels

August 16, 2023 by Lewin Day 25 Comments

Picture it. You’ve got a big roll of NeoPixels, but you have no idea how many are actually on the tape. Or you need to count how many WS2812B LEDs are in a display to properly plan your animations. Fear not, for [Gustavo Laureano] has built the perfect tool for counting the addressable LEDs.

The tool is based on a Raspberry Pi Pico, so it’s easy to replicate at home. The LED strip is simply connected to the microcontroller via a set of jumper wires going to the 5V and GND pins, while one of the Pico’s ADC pins is then connected to the strip’s GND pin after the jumper. A further GPIO pin is used to send data to the strip.

Essentially, this uses the jumper wire as a rudimentary current shunt. The code steps through the string of LEDs, turning each one on and then off in turn, comparing the value read by the ADC pin at each state. When the Pico detects no difference in current draw between the on and off states, that suggests it’s trying to turn on an LED beyond the end of the string, and thus the count is concluded.

You don’t need to understand any of that to put this device to good use, however. You can easily whip it up on a breadboard with a Pi Pico and parts you have lying around in the shop. Video after the break.

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PentaBlinky – When One LED Is Not Blinky Enough

August 10, 2023 by Dave Rowntree 4 Comments

[michimartini] over on Hackaday.io loves playing with multivibrator circuits, and has come across a simple example of a ring oscillator. This is a discrete transistor RC-delay design utilizing five identical stages, each of which has a transistor that deals with charging and discharging the timing capacitor, passing along the inverted signal to its nearest neighbor. The second transistor isn’t strictly needed and is only there to invert the signal in order to drive the LED. When the low pulse passes by the LED lights, without it you’d see all the LEDs lit bar one, which doesn’t look as good.

Compare this with an astable multivibrator to understand how it works

Essentially this circuit is just the classic astable multivibrator circuit that has been split in half and replicated so that the low pulse propagates through more stages than just the two, but thinking about it as a single stage doesn’t work so well until you draw in a couple of neighbors to help visualize the behavior better.

[michimartini] does lament that the circuit starts up in a chaotic fashion and needs a quick short applying to one transistor element in order to get it to settle into a steady rhythm. Actually, that initial behaviour could be interesting in itself, especially as the timing changes with voltage and temperature.

Anyway, we like the visual effect and the curvy organic traces. It would make a neat pin badge. Since we’re thinking about blinkies, here are couple of somewhat minimalist attempts, the world’s smallest blinky, and an even smaller one. Now, who doesn’t love this stuff?

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Got Fireflies? Try Talking To Them With A Green LED

August 6, 2023 by Donald Papp 25 Comments

[ChrisMentrek] shares a design for a simple green LED signal light intended for experiments in “talking” to fireflies. The device uses simple components like PVC piping and connectors to make something that resembles a signal flashlight with a momentary switch — a device simple enough to make in time for a little weekend experimenting.

Observe and repeat flashing patterns, and see if any fireflies get curious enough to investigate.

Did you know that fireflies, a type of beetle whose lower abdomen can light up thanks to a chemical reaction, flash in patterns? Many creatures, fireflies included, are quite curious under the right circumstances. The idea is to observe some fireflies and attempt to flash the same patterns (or different ones!) with a green LED to see if any come and investigate.

[ChrisMentrek] recommends using a green LED that outputs 565 nm, because that is very close to the colors emitted by most fireflies in North America. There’s also a handy link about firefly flashing patterns from the Massachusetts Audubon society’s Firefly Watch program, which is a great resource for budding scientists.

If staying up and learning more about nocturnal nightlife is your thing, then in between trying to talk to fireflies we recommend listening for bats as another fun activity, although it requires a bit more than just a green LED. Intrigued? Good news, because we can tell you all about the different kinds of bat detectors and what you can expect from them.

Enhance VR Immersion By Shoehorning An Ambilight Into A Headset

July 9, 2023 by Donald Papp 6 Comments

Everyone wants a wider field of view in their VR headsets, but that’s not an easy nut to crack. [Statonwest] shows there’s a way to get at least some of the immersion benefits with a bit of simple hardware thanks to the VR Ambilight.

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Two lamp versions side by side - one desk lamp and one spotlight lamp, both turned on and shining

A Tale Of Two LÄMPs

July 5, 2023 by Arya Voronova 4 Comments

Building with LEDs is a hacker pastime like no other – what’s more, if you keep playing with LED tech out there, you’re bound to build something elegant and noteworthy. For today’s fix of beautiful LED devices, take a look at the two LÄMP creations of [Jana Marie], both LED projects building upon one another. It’s not just your regular RGB LEDs – she adds a healthy mix of white and yellow LEDs, making for colors way more natural-looking and pleasant to the eye!

The first one is the LAEMP-Panel, a two-PCB sandwich, combining into a spot light you can use for any purpose where some extra LED would really shine – be it photography, accent, or mood lighting. All of these LEDs are individually controlled and from the SK6812 family, half of them YYW and half RGB variation. As for the base board, the controller is an ESP32, paired to an E75 ZigBee module – this spot light is built to be part of your home’s ZigBee network. If you look at the base board’s KiCad files, you will also notice six-pin headers on five edges – and they’re there for a reason.

The sister project to this one, the LAEMP-Prism, is a remarkable hexagonal lamp built upon the LAEMP-Panel’s PCB base, but in a desk-friendly form-factor. Six extra side panels with a generous amount of circular cutouts give you a total of 291 LEDs, mix of yellow, white and RGB as before – we got to say, from the pictures we found, it looks like a gorgeous thing to have in your house!

Such is a story of building a spotlight and a desk lamp, both using the same hardware base to accomplish quite different purposes. As is [Jana-Marie]’s tradition, these two lamps are fully open-source, complete with instructions on assembling them – everything is ready for you if you’d like to build one of your own, whichever version it may be! When it comes to lamp-building projects that excel at looks, one can’t forget the two other lamps we’ve seen a few years ago – one built with fiber optics, and another in the shape of the Moon.

Exploring The Tech Behind Concert LED Wristbands

July 1, 2023 by Danie Conradie 15 Comments

LED wristbands are now a common feature of large arena concerts and events, with a variety of capabilities and technical implementations. In the video after the break, Wall Street Journal does a fascinating deep dive into these wearable light shows.

The three main control technologies are IR light, RF radios, and Bluetooth. The IR-controlled ones are the simplest, and we’ve covered a teardown, a reverse engineering effort and reflash of the Pixmob IR armbands.

Finally, we get a good behind-the-scenes look at how they are controlled. Using pan-tilt IR emitters mounted on lighting towers, the operators can sweep across the audience controlling color and light levels or activating pre-programmed sequences.

The full control setup for RF wristbands, with transmitter on the left.

RF armbands have the simplest control setup, only requiring a single portable transmitter connected to a computer running the control software. It does however require some pre-planning for more complex light displays, to ensure each section of the audience is individually addressable.

The most advanced and expensive versions are handheld light sticks controlled via Bluetooth from an app on the users smartphone, and are popular at K-Pop concerts. Each device is linked to the users seat number, making them individually addressable and allowing the lighting operators to produce complex patterns, and even text, in the crowd.

While each of these devices is simple and underwhelming on its own, tens of thousands working together produce impressive effects and probably hide some hard-earned engineering experience.

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Do-Everything LED Indicator Light Runs From 4V To 60V

June 28, 2023 by Lewin Day 31 Comments

If you’re working with 3.3V or 5V circuits, it’s easy for you to throw on a power or status LED here or there. [Tom Gralewicz] has found himself in a pickle, though, often working on projects with voltages like 36V or 48V. Suddenly, it’s no longer practical to throw an LED and a resistor on a line to verify if it’s powered or not. Craving this simplicity, [Tom] invented the Cheap Universal LED Driver, or CULD, to do the job instead.

The CULD is designed as a simple LED indicator that will light up anywhere from 5V to 50V. It’s intended to be set-and-forget, requiring no fussing with different resistor values and no worries for the end user that excessive current draw will result.

The key part ended up being the LV2862XLVDDCR – a cheap switching regulator. It can output 1 mA to 600 mA to drive one or several LEDs, and it can do so anywhere from a 4V to 60V input. Assemble this on a coin-sized PCB with some LEDs, and you’ve got your nifty do-everything indicator light. With a bridge rectifier onboard, it’ll even work on AC circuits, too.

[Tom] has built a handful himself, but he open-sourced the design in the hopes it will go further. By his calculations, it would be possible to build these in quantities of 1000 for a BOM cost of less than $0.50 each, not counting assembly or the PCB itself. We’d love to see them become a standard part of hacker toolkits, too. If you’ve got a pick-and-place plant that’s looking for work this week, maybe get them on to something like this and see what you can do! If it turns out to be a goer, maybe drop us a note on the tipsline, yeah?