PCB Metro Maps Are A Gorgeous Labor Of Love

September 19, 2021 by Tom Nardi 21 Comments

Is your love of public transportation matched only by your passion for designing custom PCBs? If so, then you’re going to love these phenomenal transit maps created by [Chai Jia Xun]. Using the painstakingly refined principles outlined in his detailed write-up, he’s created versions for Tokyo, Singapore, and the comparatively spartan San Francisco Bay Area. All you need to make one up for your home town is an incredible amount of patience and dedication. No problem, right?

As [Xun] explains, the first part of creating one of these maps isn’t unlike generating a normal PCB. Just make a footprint for the stations, consult with Google Maps as to where they should be placed on the board, and then connect them all up with traces to stand in for the rail lines. A little silkscreen work, and you’re done.

Well…unless you want them to light up, anyway. To pull that off, [Xun] created a second PCB that places an LED behind each station hole drilled in the previous board. With a microcontroller and shift register, he’s able to selectively illuminate individual lines and run through different patterns. To combat light bleeding through the PCB, a CNC-cut piece of 3 mm MDF sits between the two boards to make sure each LED is only visible through the respective hole in the top surface.

You could call the map finished here as well, assuming you don’t mind all the stations lighting up white. If you want them to be different colors, you’ll need to insert some colored diffusers. [Xun] went through several different approaches here, but in the end, the idea that seemed to work best was to simply print out all the colored dots on a piece of transparency paper and use a second sheet of tracing paper to soften the light. Alignment here is critical, but once everything is dialed in, the results are quite impressive.

It’s quite a bit of work, and we haven’t even mentioned the fact that [Xun] had to modify the circuit when it came time to do the Tokyo map, as some MOSFETs had to be added into the mix for the microcontroller to reliably control 350+ LEDs. So there’s certainly no shame in simply buying one of them when they go on sale instead of trying to recreate it from scratch. Assuming you live in one of the cities he’s offering, anyway. Otherwise, you might want to take a look at our HackadayU class on KiCad and get yourself a comfortable chair.

What’s Cooler Than A 7-Segment Display? A 7200-Segment Display!

September 14, 2021 by Jim Heaney 17 Comments

If you look around your desk right now, odds are you’ll see a 7-segment display or two showing you some vital information like the time or today’s weather. But think of how much information you could see with over 1,100 digits, like with [Chris Combs’] 7200-segment display.

For [Chris], this project started the same way that many of our projects start; finding components that were too good of a deal to pass up on. For just “a song or two plus shipping”, he was the proud owner of two boxes of 18:88 7-segment displays, 500 modules in total. Rather than sitting and using up precious shelf space, [Chris] decided to turn them into something fancy he could hang on the wall.

the 7200 segment display grayscaling to show the time — The IS31FL3733 can produce 8 levels of dimming 8-bit PWM, allowing [Chris] to display in grayscale

The first challenge was trying to somehow get a signal to all of the individual segments. Solutions exist for running a handful of displays in one device, but there are certainly no off-the-shelf solutions for this many. Even the possible 16 addresses of the IS31FL3733 driver IC [Chris] chose for this project were not enough, so he had to get creative. Fearing potential capacitance issues with simply using an i2C multiplexer, he instead opted to run 3 different i2C busses off of a Raspberry Pi 4, to interface with all 48 controllers.

The second challenge was how to actually wire everything up. The finished display comes out to 26 inches across by 20.5 inches tall, much too large for a single PCB. Instead, [Chris] opted to design a series of self-contained panels, each with 6 of the display modules and an IS31FL3733 to drive them. While the multiplexing arrangement did leave space for more segments on each panel, he opted to go for this arrangement as it resulted in a nice, clean, 4:3 aspect ratio for the final display.

The end result was a unique and beautiful piece, which Chris titled “One-to-Many”. He uses it to display imagery and art related to the inevitability of automation, machines replacing humans, and other “nice heartwarming stuff like that”, as he puts it. There’a video after the break, but if you are interested in seeing the display for yourself, it will be on display at the VisArt’s Concourse Gallery in Rockville, MD from September 3 to October 17, 2021. More info on [Chris’s] website.

This isn’t [Chris’s] first adventure in using 7-segment displays in such a unique way, click here to read about the predecessor to this project that we covered last year.

Continue reading “What’s Cooler Than A 7-Segment Display? A 7200-Segment Display!” →

Salvaging Working LEDs From “Dead” Light Bulbs

September 14, 2021 by Tom Nardi 22 Comments

Sure the box said they would last for years or even decades, but anyone who’s picked up some bargain LED bulbs knows the reality is a bit more complicated. Sometimes a few LEDs in the array pop, reducing the overall light output. More commonly, the power supply starts to fail and the bulb begins to flicker or hum. In either event, you end up pulling the bulb and replacing it.

But [Bifferos] thinks we can do a bit better than that. Rather than just chalking it up to poor QA and tossing the bulb, why not do a little exploratory surgery to identify salvageable LEDs in an otherwise “dead” bulb? After pulling apart a couple of burned out bulbs (name brand and otherwise), he was able to pull out an impressive number of handy LED panels that could be easily repurposed. Naturally, with a little more coaxing, the individual SMD LEDs could be liberated and pushed into service as well.

Separate PCBs with banks of LEDs are ideal for reuse.

As you might expect, there are far too many different LED bulbs out there to create a comprehensive teardown guide, but [Bifferos] does provide some tricks to help get the bulb open without hurting yourself or destroying the thing in the process. Once inside, the design of the bulb will dictate what happens next. Bulbs with multiple arrays of LEDs on their own PCBs can be easily broken down, but if there’s just the single board, you may want to pull the LEDs off individually. To that end, the write-up demonstrates efficient methods of stripping the LEDs using either hot air or a pair of soldering irons.

We’ve talked previously about the rather underwhelming performance of modern LED bulbs compared to the manufacturer’s lofty claims. We’d rather see these bulbs designed well enough that they actually live up to their full potential, but the ability to salvage useful components from the failed luminaries at least softens the blow of having to toss them early. Though that’s not the only reason you should disassemble your LED bulbs before you put them in the trash.

Interactive LED Shoes That Anyone Can Build!

September 5, 2021 by Lewin Day 3 Comments

Normally when we see blinky projects these days, it’s using addressable LED strips with WS2812Bs, or similar alternatives. However, old-school blobby round LEDs are still on the market, and can still be put to great use. These DIY LED shoes from [TechnoChic] are an excellent example of just that.

The shoes use big 10mm LEDs that have color-changing smarts baked in. Simply power them up and they’ll fade between a series of colors. They’re run from a coin cell sewn on to the side of each shoe, with the LEDs jammed into the rear of the sole. A conductive product called Maker Tape is then used to create a circuit for the LEDs and the coin cell, along with a pressure switch inside each shoe. When the wearer puts weight on their heel, the switch conducts, lighting up the LEDs as the wearer takes each step.

This isn’t the first time we’ve seen a pair of shoes bedazzled with LEDs, but it’s arguably the easiest version of the concept to grace these pages. This is a quick way to create interactive flashing LED gadgets, and a great way for beginner makers to jazz up their projects.

Continue reading “Interactive LED Shoes That Anyone Can Build!” →

Small sensor built into audio jack, held in tweezers

Measuring LED Flicker, With Phototransistor And Audio App

September 1, 2021 by Donald Papp 26 Comments

No one likes a flickering light source, but lighting is often dependent on the quality of a building’s main AC power. Light intensity has a close relation to the supply voltage, but bulb type plays a role as well. Incandescent and fluorescent bulbs do not instantly cease emitting the instant power is removed, allowing their output to “coast” somewhat to mask power supply inconsistencies, but LED bulbs can be a different story. LED light output has very little inertia to it, and the quality of both the main AC supply and the bulb’s AC rectifier and filtering will play a big role in the stability of an LED bulb’s output.

Mobile phone spectrum analyzer pointed at light source — The DIY photosensor takes the place of the microphone input.

[Tweepy] wanted to measure and quantify this effect, and found a way to do so with an NPN phototransistor, a resistor, and a 3.5 mm audio plug. The phototransistor and resistor take the place of a microphone plugged into the audio jack of an Android mobile phone, which is running an audio oscilloscope and spectrum analyzer app. The app is meant to work with an audio signal, but it works just as well with [Tweepy]’s DIY photosensor.

Results are simple to interpret; the smoother and fewer the peaks, the better. [Tweepy] did some testing with different lighting solutions and found that the best performer was, perhaps unsurprisingly, a lighting panel intended for photography. The worst performer was an ultra-cheap LED bulb. Not bad for a simple DIY sensor and an existing mobile phone app intended for audio.

Want a closer look at what goes into different LED bulbs and how they tick? We have you covered. Not all LED bulbs are the same, either. Some are stripped to the bone and others are stuffed with unexpected goodness.

RGB LED Matrix Helps Etch-a-Sketch Scratch Out A 21st Century Existence

August 22, 2021 by Kristina Panos 3 Comments

We never did crack open our Etch-a-Sketch, but we did scrape out a window large enough to really check out the mechanism inside. [MrLangford] is bringing the Etch-a-Sketch into the 21st century while at the same time, bringing an even bigger air of mystery, at least for the normies.

Instead of scraping aluminum powder off of plastic by driving a stylus on an x-y gantry with a pair of knobs, this bad boy uses rotary encoders to move the cursor around and put down squares of colored light. The familiar movements are there — the left knob moves the cursor left and right, and the right knob moves it up and down. But this wouldn’t be a 21st century toy without newfangled features. Push the left encoder down and it cycles through eight color choices, or push the right one down to go through them backwards. We hope one of the colors is setting it back to darkness in case you screw up. And while we’re dreaming up improvements, it would be awesome to add an accelerometer so you could shake it clear like a standard Etch-a-Sketch.

Inside the requisite red enclosure with white knobs are an Arduino Nano and a 16×16 RGB LED matrix. The enclosure is four sheets of 6mm MDF glued together, and we like the use of protoboard to distribute GND and 5 V in the name of keeping the thing slim.

If you’re not much of an artist, here’s a TV-sized Etch-a-Sketch build that can draw by itself.

DIY LED Cube For The Masses

August 22, 2021 by Inderpreet Singh 6 Comments

No matter what the size or shape of an LED, it brings out the curiosity in every hardware nerd, and is the lifeblood of badge life around the planet. Then there is the LED cube that takes LEDs to all sides — literally. [Tomverbeure] had his own adventure of creating an LED Cube by piecing together Pixel Purses and a Cisco3G Modem.

A quick search for Pixel Purse on the internet reveals a toy lady’s handbag with an LED matrix embedded in one side. [tomverbeure] tore down 12 of these so as to get two panels for each side of his creation. After a little bit of experimenting with PCB corner brackets, he finally got it right and he is able to merge the pieces together to form the cube.

Next comes the brain and the elected device An FPGA from an HWIC-3G-CDMA modem. Cisco routers have extension slots and the HWIC connector on this particular piece had usable GPIOs that connect directly to the Altera FPGA. Inside the FPGA, a RISC-V soft CPU is used to generate images that get processed and dispatched in a hardware block. [Tomverbeure] does a detailed explanation of the implementation for all the blocks which were written in SpinalHDL. The video below shows the project in action.

We love the detail that [Tomverbeure] provides and hope it does not drive up the prices of the pixel purse too much. If you are looking for a more fine pitched cube, look no further than this one. If you end up making your own, be sure to send us a link.