Tidy POV Display Using The ESP32

November 23, 2022 by Dave Rowntree 9 Comments

Chinese Youtuber [corebb] presents the second version of his POV display. The earlier version used 5050-sized SMT addressable LEDs, which didn’t give great resolution, so he rev’d the design to use a much higher number (160 to be exact) of APA102 LEDs. These are 2mm on the side, making them a little more difficult to handle, so after some initial solder paste wobbles, he decided to use a contract assembly house to do the tricky bit for him. This failed as they didn’t ‘understand’ the part and placed them the wrong way around! Not to be deterred, he had another go with a modified solder stencil, and eventually got the full strip to light up correctly.

Based on an ESP32 (using the Arduino stack) and SDCard for control, and a LiPo cell charged wirelessly, the build is rather tidy. A couple of hall effect switches are mounted at the start of each of the two arms, presumably lining

up with a magnet on the case somewhere, although this isn’t clear. The schematic and PCB appear to have been designed with JLCEDA, which is a repackaging of EasyEDA. We can see the attraction with the heavy integration of this with the JLC and LCSC services. It appears that he even managed to get streamed video working — showing a live video from a webcam — which is quite an undertaking to pull off when you think how much processing needs to happen in real-time. As he alludes to in the video, trying to increase the resolution beyond this point is not viable with the processing capability of the ESP32.

A resin-printed case finishes off the build, with a screw-thread mount added to the rear, to allow typical camera mounts to be used to hold the thing down. A smart move we think.

We love POV displays around here, this spherical POV display is especially fabulous, but you don’t need fancy hardware if you have a handy ceiling fan and a bit of protoboard spare.

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Surface Mount Breathing Light PCB, using LM358 op-amp

Surface-Mount Light Breathes Life Into Your Project

November 11, 2022 by Dave Walker 13 Comments

If you’ve ever seen those gadgets with the “breathing light” LEDs on them and wondered how to do it, then [DIY GUY Chris] can show you how to design your own surface-mount version, using only analogue electronics.

Simulation trace showing the LED breathing light circuit operating. Traces for voltage and current are shown over a few seconds — The LED current tracks up and down in an approximately triangular-wave pattern

The circuit itself is built around a slow triangular-wave oscillator, that ramps the current up and down in the LEDs to make it look as if the lights are breathing in and out. The overall effect is rather pleasing, and the oscillation speed can be adjusted using the on-board potentiometer.

This project is actually an update to a previous version that used through-hole components (also shown in the video below), and goes to show that revisiting completed projects can give them a new lease of life. It also shows how easy it has become to design and order custom circuit boards these days. It’s not so long ago that a project like this would have been either made on stripboard or etched from copper-plated FR4 in a bubbling tank of acid!

If you have revisited an old project that you’re proud of and would like to show others, why not drop us a message on our tips line?

We have covered some other options for breathing LEDs in the past, such as this digital logic version, and this Arduino library that has a host of other effects to choose from, too. Continue reading “Surface-Mount Light Breathes Life Into Your Project” →

"The Great Resistor" color code illumination project

The Great Resistor Embiggens The Smallest Value

November 5, 2022 by Dave Walker 29 Comments

With surface-mount components quickly becoming the norm, even for homebrew hardware, the resistor color-code can sometimes feel a bit old-hat. However, anybody who has ever tried to identify a random through-hole resistor from a pile of assorted values will know that it’s still a handy skill to have up your sleeve. With this in mind, [j] decided to super-size the color-code with “The Great Resistor”.

Resistor color code from Wikipedia with white background — How the resistor color-code bands work

At the heart of the project is an Arduino Nano clone and a potential divider that measures the resistance of the test resistor against a known fixed value. Using the 16-bit ADC, the range of measurable values is theoretically 0 Ω to 15 MΩ, but there are some remaining issues with electrical noise that currently limit the practical range to between 100 Ω and 2 MΩ.

[j] is measuring the supply voltage to help counteract the noise, but intends to move to an oversampling/averaging method to improve the results in the next iteration.

The measured value is shown on the OLED display at the front, and in resistor color-code on an enormous symbolic resistor lit by WS2812 RGB LEDs behind.

Inside view of the great resistor showing WS2812 LEDs and baffle plates — Inside The Great Resistor, the LEDs and baffle plates make the magic work

Precision aside, the project looks very impressive and we like the way the giant resistor has been constructed. It would look great at a science show or a demonstration. We’re sure that the noise issues can be ironed out, and we’d encourage any readers with experience in this area to offer [j] some tips in the comments below. There’s a video after the break of The Great Resistor being put through its paces!

If you want to know more about the history of the resistor color code bands, then we have you covered. Alternatively, how about reading the color code directly with computer vision?

Continue reading “The Great Resistor Embiggens The Smallest Value” →

Screenshot from the video showing comparisons between diffused light pictures at different brightnesses and diffusers applied

LED Diffusers Confusing? Organize A Practical Contest

November 3, 2022 by Arya Voronova 8 Comments

We all want a nice and shiny LED strip that doesn’t actually look like it consists of individual LEDs – a bar of uniform light is just that much more attractive. There’s all kinds of diffusion options available out there, but they can be confusing – sometimes you’d just like to know, which one is better? If there’s one thing that could easily settle this, it’s a practical test, and that’s what [The Hook Up] has devised for us to learn from.

First off, he talks about LED strips available – between 30, 60 and 144 LED per meter variations, the latter is going to be easier to diffuse than the former. From there, there’s a few different kinds of diffuser covers and aluminum profiles you can get, and [The Hook Up] pairs them in combinations, filming them from a distance and giving us concise visuals of how each combination works at different duty cycles, as well as making brightness measurements every now and then to evaluate losses of different diffuser layers. He proposes a simple rule – when picking a diffuser, distance between the LEDs and the diffuser has to be larger than the between-LED distance, and experiments confirm that. In the end, one of the takeaways is that the differences between 60LED/m and 144LED/m strips are not significant enough that they can’t be compensated for with a decent diffuser.

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A segmented lamp made of circular slices of plywood. They are arranged as shutters around a long, skinny LED bulb in the center that gives off an incadescent-looking glow. A cord trails off to the left against the grey background.

Plywood Lamp Has Customizable Light Output

November 1, 2022 by Navarre Bartz 2 Comments

There’s something about light fixtures that attracts makers like moths to a flame. [danthemakerman] wanted something with a more configurable light output and built this Sculptural and Customizable Plywood Lamp.

In his detailed build log, [danthemakerman] describes how he wanted something “sort of like an analog dimmable light.” By using a stack of split plywood donuts hinged on a brass rod, he can vary the output and shape of the lamp. These shutters allow the lamp to go from bright to nightlight without using any electrical dimming components.

The plywood was rough cut on a bandsaw before being turned on a lathe. The light cover sections were then hollowed out with a Forstner bit and split in half. The tricky bit is the overlap of the cut on the hinge side of the shutters. Cutting the piece exactly in half would’ve required a lot more hardware to make this lamp work than what was achieved by patient woodworking.

If you’d like to see more ways to make light fixtures with plywood, check out this Hexagonal Lamp, these Upcycled Plywood and Glass Lamps, or this Laser-cut Sphere Lampshade that Packs Flat.

Lighting Up Glue Stick Bicycle Tyres With RGB

October 31, 2022 by Danie Conradie 28 Comments

Being visible to motorists is a constant concern for cyclists, but we doubt [The Q] will have this problem with his RGB LED illuminated tires made from glue sticks.

The project started with a set of 3D-printed tire molds that bolt to the standard wheels. A bot of melted glue sticks is poured into the mold, allowed to cool, and the mold sections are removed with the help of a heat gun after cooling. We doubt the weight and hardness make the tires particularly practical, but you can’t make normal tires glow from the inside.

The idea to illuminate the tires probably came after molding, because they had to be cut off to fit the LEDs. [The Q] built a simple hot wire jig with a piece of nichrome wire between two screws and used it to cut a few millimeters from the inside of the tire and fit a sleeved RGB LED strip in the wheel. Power come from a set of three 18650 batteries housed with a wireless controller in a 3D printed hub-mounted enclosure.

Like [The Q]’s hubless and partial wheel bicycles, it’s a definite head-turner, with function following form.

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A prosthetic eye anodized green around the edges with a yellow and blue "iris" surrounding an LED center.

Skull Lamp Illuminates The Cyberpunk Future

October 26, 2022 by Navarre Bartz 11 Comments

Cyberpunk is full of characters with cool body mods, and [bsmachinist] has made a prosthetic eye flashlight (TikTok) that is both useful and looks futuristic. [via Reddit]

[bsmachinist] has been machining titanium prosthetic eyes for over five years now, and this latest iteration, the Skull Lamp, has a high brightness LED that he says is great for reading books at night as well as any other task you might have for a headlamp. Battery life is reported as being 20 hours, and the device is switched by passing a magnet (Instagram) near the prosthetic.

We love seeing how prosthetics have advanced in the last few years with the proliferation of advanced tools for makers. Some other interesting prosthetics we’ve covered are this DIY Socket for Prosthetics with a built-in charger and power supply and several different prosthetic projects for kids including these Heroic Prosthetics by Open Bionics, the E-Nable Alliance, and a Kid Who Designed his Own Prosthetic.

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