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.

Landscape Lighting that Also Texts

Your local hardware store or garden supply center probably has everything you need to install landscape lighting all around your property. What’s a little less likely is coming out of that situation with fewer holes in your wallet than in your yard. And even then, it’s pretty much guaranteed that any off-the-shelf equipment won’t send you a text message when your landscape lighting isn’t working properly. [Mark]’s landscape lighting system does, though!

Powered by a Raspberry Pi, this landscape lighting system has every feature imaginable. It can turn the lighting on at sunset and turn it off at a set or random time later in the evening. There’s a web interface served from the Pi that allows further user control. The Raspberry Pi also monitors the lighting and can sense when one of the lights burns out. When one does, the Pi uses Twillo to send a text message notification.

There’s not many more features we can imagine packing into a setup like this. Of course, if you don’t have a spare Pi around you can probably manage to get the job done with an ESP8266, or even an old-fashioned Arduino.

VW Engineer Pleads Guilty To Conspiracy

[James Liang], an engineer at Volkswagen for 33 years, plead guilty today to conspiracy. He was an engineer involved in delivering Diesel vehicles to market which could detect an emissions test scenario and perform differently from normal operation in order to pass US emission standards.

A year ago we talked about the Ethics in Engineering surrounding this issue. At the time we wondered why any engineer would go along with a plan to defraud customers. We may get an answer to this after all. [Mr. Liang] will cooperate with authorities as the VW probe continues.

According to information in the indictment, none of this happened by mistake (as we suspected). There was a team responsible for developing a mode that would detect a test and pass inspection after the company discovered the engine could not otherwise pass. It’s not hard to see the motivation behind this — think of the sunk cost in developing an engine design. The team responsible for cheating the tests went so far as to push software updates in 2014 which made the cheat better, and lying about the existence of these software “features” when questioned by authorities (again, according to the indictment).

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.

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Books You Should Read: Poorly Made In China

This book is scary, and honestly I can’t decide if I should recommend it or not. It’s not a guide, it doesn’t offer solutions, and it’s full of so many cautionary tales and descriptions of tricks and scams that you will wonder how any business gets done in China at all. If you are looking for a reason not to manufacture in China, then this is the book for you.

The author is not involved in the electronics industry. Most of the book describes a single customer in the personal products field (soap, shampoo, lotions, creams, etc.). He does describe other industries, and says that in general most factories in any industry will try the same tricks, and confirms this with experiences from other similar people in his position as local intermediary for foreign importers.

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Very Simple PC Frequency Counter Works Up To 100MHz

We all use 74 logic in our projects as general purpose logic interfacing glue. These chips have become as ubiquitous as a general-purpose op-amp, or even as passive components. In most cases we’re not demanding much of them, and power requirements aside an original 74 chip from the dawn of the series could probably do the same job that we’re putting a more modern variant to work on.

It is easy therefore to forget that 74 logic is a field that has seen continuous improvement and innovation reflecting the developments elsewhere in electronics, and the most modern 74 versions hide some impressively high specifications.

A good example comes via a project from [Scott, AJ4VD], a very simple frequency counter that uses a single 74 series chip at its business end, and counts to over 100MHz. The chip in question is a 74LV8154 dual 16-bit counter which he is using as a prescaler to deliver a rate more acceptable to an ATMega328 microcontroller that does the counting. As he points out, the accuracy of a frequency counter is only as good as its gate timing, and he ensures as accurate a seconds-worth of pulses as he can with a 1PPS signal derived from an inexpensive GPS receiver. The 328 makes its counting available to a host computer via a serial port, and can be easily read through a terminal. He’s built it dead-bug style on a piece of unetched PCB, on which the simplicity of the circuit is evident.

There was a time when a project like this one would have required multiple integrated circuits including a probably quite expensive purpose-built prescaler. Cheap glue logic has now advanced to a stage at which it can be done instead at commodity prices, and we like that.

We’ve featured a few 74-series counters before, including this old-school one and this one also using a 74LV8154.

Life On Contract: Estimating Project Time

You sit there, irritation bubbling deep within as minute forty-five of the meeting ticks past on the clock in the corner of the office. Fight or flight is in a contest with your attention span as you struggle to keep an interested look on your face while they drone on. Real work could be done in this time. Maybe if you go to the bathroom you could sort of… fast forward the meeting. Panicked thinking continues for a bit until your awareness snaps back to the babble of words in the room.

“How long will it take you to do this?” the manager asks.

“A couple of days maybe?” You reply in turn. The manager nods and you take your escape. Little do you know that you have failed.

The project swerves out of control. Two days on the dot the manager is there expecting results. How? How did this happen again? It felt right! Two days is all you’d need to do such a simple project. It ended up taking a week.

The next meeting you say two weeks just to be sure. Everyone nods gravely, upset that something would take so long, but the work must be done. Two days later you sheepishly wander into the manager’s office with a completed project. He looks pleased but confused. The next meeting, he insists that you can do it in half the time. You and your fragile pride bowl ahead only to deliver late. The mystery!

This was my life until I started bugging the more experienced around me. I learned a lot from them and I ended up distilling it down into a few rules.

  1. There Is No Other Unit Than Hours
  2. Be honest.
  3. Get Granular.
  4. Promise a Range. Give a Deadline.

Why?

Why does someone want a time estimate? What are they going to do with this information? When working on a contract job it often feels like sticking a foot in a trap when a time estimate is given. Are they going to hold me to this? What if it goes wrong? After all, we are not fortune tellers. Unless the manager is extremely bad or you show yourself to be extremely lax in your duties, it is unlikely that a time estimate will be used against you.

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