Hackaday Prize Entry: Characterizing LED and Laser Diodes

Needless to say, we’re fascinated by LEDs, laser diodes, and other blinkies. Although we can get just about any light emitting thing, the data sheets aren’t always accurate or available. For his Hackaday Prize entry, [Ted] is building a device to characterize the efficiency, I/V curve, and optical properties of all the blinkies. It’s a project to make glowy stuff better, and a great entry for the Hackaday Prize.

The inspiration for this project came from two of [Ted]’s projects, one requiring response curves for LEDs, and laser diodes for another. This would give him a graph of optical output vs. current, angular light output distribution, and the lasing threshold for laser diodes. This data isn’t always available in the datasheet, so a homebrew tool is the only option.

The high-level design of this tool is basically a voltmeter and ammeter measuring a glowy diode, producing IV curves and measuring optical output. That takes care of all the measurements except for the purely optical properties of a LED. This is measured by a goniometer, or basically putting the device under test on a carriage attached to a stepper motor and moving it past a fixed optical detector.

If you’re wondering why this device is needed and a simple datasheet is insufficient, check this out. [Ted] measured the efficiency of a Luxeon Z LED, and found the maximum efficiency is right around 10mA. The datasheet for this LED shows a nominal forward current of 500mA, and a maximum of 1000mA. If you just looked at the datasheet, you could easily assume a device powered for years by a coin cell would be impossible. It’s not, and [Ted]’s device gave us this information.

NES Zapper: Improved with Lasers

The Zapper gun from the original Nintendo was ahead of its time. That time, though, was around 30 years ago and the iconic controller won’t even work with most modern televisions. With a little tinkering they can be made to work, but if you want to go in a different direction they can be made to do all kinds of other things, too. For example, this one can shoot green lasers and be used as a mouse.

The laser pointer was installed in the gun using a set of 3D printed rings to make sure the alignment was correct. It’s powered with a Sparkfun battery pack and control board which all fit into the gun’s case. The laser isn’t where the gun really shines, though. There’s a Wiimote shoved in there too that allows the gun to be used as a mouse pointer when using it with a projector. Be sure to check out the video below to see it in action. Nothing like mixing a little bit of modern Nintendo with a classic!

The Wiimote is a great platform for interacting with a computer. Since the Wii was released it’s been relatively easy to interface with them via Bluetooth. One of the classic Wiimote hacks is using an IR pen and projector to create a Smart Board of sorts for a fraction of the price. They’ve also been used with some pretty interesting VR displays.

Continue reading “NES Zapper: Improved with Lasers”

NES Light Gun Fires Awesome Laser Effect

[Seb Lee-Delisle]’s NES lightgun gave us pause as the effect is so cool we couldn’t quite figure out how he was doing it at first. When he pulls the trigger there erupts the beam of light Sci Fi has trained us to expect, then it explodes in a precision sunburst of laserlight at the other end as smoke gently trails from the end of the barrel. This is a masterpiece of hardware and trickery.

seb-lee-delisle-nes-zapper-trick-thumb
Demo video posted by @seb_ly

The gun itself is a gutted Nintendo accessory. It looks like gun’s added bits consist of two LED strips, a laser module (cleverly centered with two round heatsinks), a vape module from an e-cigarette, a tiny blower, and a Teensy.  When he pulls the trigger a cascade happens: green light runs down the side using the LEDs and the vape module forms a cloud of smoke in a burst pushed by the motor. Finally the laser fires as the LEDs finish their travel, creating the illusion.

More impressively, a camera, computer, and 4W Laser are waiting and watching. When they see the gun fire they estimate its position and angle. Then they draw a laser sunburst on the wall where the laser hits. Very cool! [Seb] is well known for doing incredible things with high-powered lasers. He gave a fantastic talk on his work during the Hackaday Belgrade conference in April. Check that out after the break.

So what does he have planned for this laser zapper? Laser Duck Hunt anyone? He has a show in a month called Hacked On Classics where this build will be featured as part of the Brighton Digital Festival.

Continue reading “NES Light Gun Fires Awesome Laser Effect”

How Accurate Is Microstepping Really?

Stepper motors divide a full rotation into hundreds of discrete steps, which makes them ideal to precisely control movements, be it in cars, robots, 3D printers or CNC machines. Most stepper motors you’ll encounter in DIY projects, 3D printers, and small CNC machines are bi-polar, 2-phase hybrid stepper motors, either with 200 or — in the high-res variant — with 400 steps per revolution. This results in a step angle of 1.8 °, respectively 0.9 °.

Can you increase the resolution of this stepper motor?

In a way, steps are the pixels of motion, and oftentimes, the given, physical resolution isn’t enough. Hard-switching a stepper motor’s coils in full-step mode (wave-drive) causes the motor to jump from one step position to the next, resulting in overshoot, torque ripple, and vibrations. Also, we want to increase the resolution of a stepper motor for more accurate positioning. Modern stepper motor drivers feature microstepping, a driving technique that squeezes arbitrary numbers of microsteps into every single full-step of a stepper motor, which noticeably reduces vibrations and (supposedly) increases the stepper motor’s resolution and accuracy.

On the one hand, microsteps are really steps that a stepper motor can physically execute, even under load. On the other hand, they usually don’t add to the stepper motor’s positioning accuracy. Microstepping is bound to cause confusion. This article is dedicated to clearing that up a bit and — since it’s a very driver dependent matter — I’ll also compare the microstepping capabilities of the commonly used A4988, DRV8825 and TB6560AHQ motor drivers.

Continue reading “How Accurate Is Microstepping Really?”

Bachelor Builds Enormous Laser Cutter, Nobody Complains

Nothing says swinging 21st-century bachelor pad better than a laser cutter. To really make a statement, you want a custom-built, 100 Watt, 1200mm x 900mm laser cutter.

The bachelor in question, [drandolph], rightly points out that a $6,000 build that takes up a significant fraction of the floor space in one’s apartment is better attempted without the benefit of spousal oversight. Still, what spouse couldn’t love the finished product? With a custom aluminum extrusion frame (which barely made the trip from China intact) it’s a sturdy affair, and who could deny the appeal of the soft glow of an LED-illuminated work chamber? A custom exhaust system with sound-deadening, a water chiller for laser cooling, an Arduino-controlled status beacon – there’s even a 3-D printed beer holder on the control panel! And think of all the goodies that will come off the enormous bed of this thing. Note to self: make sure wife sees this post.

There are cheaper and smaller laser cutters, but what’s the point if you have the freedom to go big?

[via r/DIY]

Ion Trap Makes Programmable Quantum Computer

The Joint Quantum Institute published a recent paper detailing a quantum computer constructed with five qubits formed from trapped ions. The novel architecture allows the computer to accept programs for multiple algorithms.

Quantum computers make use of qubits and trapped ions–ions confined with an electromagnetic field–are one way to create them. In particular, a linear radio frequency trap and laser cooling traps five ytterbium ions with a separation of about 5 microns. To entangle the qubits, the device uses 50 to 100 laser pulses on individual or pairs of ions. The pulse shape determines the actual function performed, which is how the device is programmable. The operations depend on the sequence of laser pulses that activate it. Continue reading “Ion Trap Makes Programmable Quantum Computer”

The Quest for Mice With Frickin’ Laser Beams (Pointed At Their Brains), Building A Laser Controller

The logo for the field is kind of cute though.
The logo for the field is kind of cute though.

[Scott Harden] is working on a research project involving optogenetics. From what we were able to piece together optogenetics is like this: someone genetically modifies a mouse to have cell behaviors which can activated by light sensitive proteins. The mice then have a frikin’ lasers mounted on their heads, but pointing inwards towards their brains not out towards Mr. Bond’s.

Naturally, to make any guesses about the resulting output behavior from the mouse the input light has to be very controlled and exact. [Scott] had a laser and he had a driver, but he didn’t have a controller to fire the pulses. To make things more difficult, the research was already underway and the controller had to be built

The expensive laser driver had a bizarre output of maybe positive 28 volts or, perhaps, negative 28 volts… at eight amps. It was an industry standard in a very small industry. He didn’t have a really good way to measure or verify this without either destroying his measuring equipment or the laser driver. So he decided to just build a voltage-agnostic input on his controller. As a bonus the opto-isolated input would protect the expensive controller.

The kind of travesty that can occur when [Stefan Kiese] doesn't have access to nice project boxes.
The kind of travesty that can occur when [Scott] doesn’t have access to nice project boxes.
The output is handled by an ATtiny85. He admits that a 555 circuit could generate the signal he needed, but to get a precision pulse it was easier to just hook up a microcontroller to a crystal and know that it’s 100% correct. Otherwise he’d have to spend all day with an oscilloscope fiddling with potentiometers. Only a few Hackaday readers relish the thought as a relaxing Sunday afternoon.

He packaged everything in a nice project box. He keeps them on hand to prevent him from building circuits on whatever he can find. Adding some tricks from the ham-radio hobby made the box look very professional. He was pleased and surprised to find that the box worked on his first try.