Robert Hall And The Solid-State Laser

May 22, 2018 by 14 Comments

The debt we all owe must be paid someday, and for inventor Robert N. Hall, that debt came due in 2016 at the ripe age of 96. Robert Hall’s passing went all but unnoticed by everyone but his family and a few close colleagues at General Electric’s Schenectady, New York research lab, where Hall spent his remarkable career.

That someone who lives for 96% of a century would outlive most of the people he had ever known is not surprising, but what’s more surprising is that more notice of his life and legacy wasn’t taken. Without his efforts, so many of the tools of modern life that we take for granted would not have come to pass, or would have been delayed. His main contribution started with a simple but seemingly outrageous idea — making a solid-state laser. But he ended up making so many more contributions that it’s worth a look at what he accomplished over his long career.

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Hacking A Cheap Laser Rangefinder

May 22, 2018 by 33 Comments

When a new piece of technology comes out, the price is generally so high that it keeps away everyone but the die hard early adopters. But with time the prices inch down enough that more people are willing to buy, which then drives the prices down even more, until eventually the economies of scale really kick in and the thing is so cheap that it’s almost an impulse buy. Linux SBCs, Blu-ray lasers, 3D printers; you name it and the hacker community has probably benefited from the fact that it’s not just the hacker community that’s interested anymore.

Which is exactly what’s started to happen with laser rangefinders. Once almost exclusively a military technology, you can now pick a basic “laser tape measure” for less than $40 USD from the normal overseas suppliers. Unfortunately, as [iliasam] found, they aren’t particularly well suited other tasks. For one there’s no official way of getting the data out of the thing, but the other problem is that the sample rate is less than one per second. Believing the hardware itself was promising enough, he set out to reverse engineer and replace the firmware running on one of these cheap laser rangefinders (Google Translate from Russian).

His blog post is an absolute wealth of information on how these devices operate, and a must read for anyone interested in reverse engineering. But the short version is that he figured out a way to reprogram the STM32F100C8T6 microcontroller used in the device, and develop his own firmware that addresses the usability concerns of this otherwise very promising gadget.

With some minor hoop jumping, the laser tape measure PCB can be hooked up to an ST-Link programmer, and the firmware provided by [iliasam] can be used to enable an easy to use serial interface. Perfect for pairing with an Arduino or Raspberry Pi to get fast and accurate range data without breaking the bank.

It probably won’t surprise you to see this isn’t the first time [iliasam] has gotten down and dirty with a laser rangefinder. This extremely impressive build from last year allowed for incredibly accurate 3D scans of his room, and before that he created his own rangefinder from scratch.

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Hands-On: Flying Drones With Scratch

May 22, 2018 by 8 Comments

I’ll admit it. I have a lot of drones. Sitting at my desk I can count no fewer than ten in various states of flight readiness. There are probably another half dozen in the garage. Some of them cost almost nothing. Some cost the better part of a thousand bucks. But I recently bought a drone for $100 that is both technically interesting and has great potential for motivating kids to learn about programming. The Tello is a small drone from a company you’ve never heard of (Ryze Tech), but it has DJI flight technology onboard and you can program it via an API. What’s more exciting for someone learning to program than using it to fly a quadcopter?

For $100, the Tello drone is a great little flyer. I’d go as far as saying it is the best $100 drone I’ve ever seen. Normally I don’t suggest getting a drone with no GPS since the price on those has come down. But the Tello optical sensor does a great job of keeping the craft stable as long as there is enough light for it to see. In addition, the optical sensor works indoors unlike GPS.

But if that was all there was to it, it probably wouldn’t warrant a Hackaday post. What piqued my interest was that you can program the thing using a PC. In particular, they use Scratch — the language built at MIT for young students. However, the API is usable from other languages with some work.

Information about the programming environment is rather sparse, so I dug in to find out how it all worked.

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Raspberry Pi Keeps Cool

May 22, 2018 by 39 Comments

In general, heat is the enemy of electronics. [Christopher Barnatt] is serious about defeating that enemy and did some experiments with different cooling solutions for the Raspberry Pi 3. You can see the results in the video below.

A simple test script generated seven temperature readings for each configuration. [Barnatt] used a bare Pi, a cheap stick-on heatsink, and then two different fans over the heatsink. He also rigged up a large heatsink using a copper spacer and combined it with the larger of the two fans.

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A Parallel Port Synthesiser For Your DOS PC

May 22, 2018 by 12 Comments

It is a great shame that back in the days when a typical home computer had easy low-level hardware access that is absent from today’s machines, the cost of taking advantage of it was so high. Professional PCBs were way out of reach of a home constructor, and many of the integrated circuits that might have been used were expensive and difficult to source in small quantities.

Here in the 21st century we have both cheap PCBs and easy access to a wealth of semiconductors, so enthusiasts for older hardware can set to work on projects that would have been impossible back in the day. Such an offering is [Serdef]’s Tiny Parallel Port General MIDI Synthesizer for DOS PCs, a very professionally produced synth that you might have paid a lot of money to own three decades ago.

At its heart is a SAM2695 synthesiser chip, and the board uses the parallel port as an 8-bit I/O port. The software side is handled by a TSR (a Terminate and Stay Resident driver loaded at startup, for those of you who are not DOS aficionados), and there are demonstrations of it running with a few classic games.

If the chip used here interests you, you might like to look at a similar project for an Arduino. The Kickstarter we covered is now long over, but you can also find it on GitHub.

Dual SDR Receives Two Bands At Once

May 21, 2018 by 15 Comments

There was a time when experimenting with software defined radio (SDR) was exotic. But thanks to cheap USB-based hardware, this technology is now accessible to anyone. While it is fun to play with the little $20 USB sticks, you’ll eventually want to move up to something better and there are a lot of great options. One of these is SDRPlay, and they recently released a new piece of hardware — RSPduo — that incorporates dual tuners.

We’ve talked about using the SDRPlay before as an upgrade from the cheap dongles. The new device can tune either a single 10 MHz band over the range of 1 kHz to 2 GHz, or you can select two 2 MHz bands. This opens up a lot of applications where you need to pick up signals in different areas of the spectrum (e.g., monitoring both sides of a cross-band repeater).

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Online Logic Simulator Is Textual — No, Graphical

May 21, 2018 by 6 Comments

We have a bit of a love/hate relationship with tools in the web browser. For education or just a quick experiment, we love having circuit analysis and FPGA tools at our fingertips with no installation required. However, we get nervous about storing code or schematics we might like to keep private “in the cloud.” However, looking at [Lode Vandevenne’s] LogicEmu, we think it is squarely in the educational camp.

You can think of this as sort of Falstad for logic circuits (although don’t forget Falstad does logic, too). The interface is sort of graphical, and sort of text-based, too. When you open the site, you’ll see a welcome document. But it isn’t just a document, it has embedded logic circuits in it that work.

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