Author: Al Williams

4464 Articles

Homebrew Analog Scope Project Log

September 1, 2015 by 7 Comments

[GK] had some old CRTs lying around, so naturally he decided to build an old school analog scope with one of them. Lucky for us, he’s been documenting his progress. Since it was a big project to tackle, he started out with Spice modeling to work out all the right values.

Prototyping the power supply took some custom transformer winding, but when done, the power supply did the job. Although he’s still wiring up the Z (intensity) axis, the scope is already capable of displaying signals and even text characters using a character generator he built earlier (see video below).

[GK] spends most of the time so far talking about the high voltage power supply design. For the particular tubes he had on hand he needed +200V, -400V, -550V, and 6.3VAC for the CRT heater. This is certainly not the typical Arduino-based digital scope that everyone builds at least once.

We love analog scopes for art projects, logic analyzer conversions, and gaming. Of course, if you don’t have an old CRT in your parts bin, you might consider trying a laser.

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Custom Threaded Inserts For 3D Printing

August 31, 2015 by 29 Comments

There’s a variety of ways to add threaded holes to 3D printed objects. You can tap a hole, but the plastic isn’t always strong enough. Nut traps work, but aren’t very attractive and can be difficult to get exactly the right size. If you try to enclose them, you have to add a manual step to your printing process, too. You can buy threaded inserts (see video below) but that means some other piece of hardware to have to stock in your shop.

[PeterM13] had a different idea: Cut a piece of threaded stock, put nuts on the end and heat it up to let the nuts reform the plastic. This way the nut traps wind up the perfect size by definition. He used two nuts aligned and secured with thread locker. Then he used a hot air gun to only heat the metal (so as to reduce the chance of deforming the actual part). Once it was hot (about 15 seconds) he pulled the nuts into the open hole, where it melted the plastic which grips the nuts once cooled again.

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Go Forth On A Breadboard

August 30, 2015 by 30 Comments

Forth isn’t a shiny new programming language, but it has a staunch following because it is lightweight and elegant. The brainchild of [Chuck Moore], the language is deceptively simple. Words are character sequences delimited by spaces. In its simplest form, Forth knows a few basic words including–and this is the key–a word to define other words.

[Jean-Claude Wippler] likes to experiment with physical computing and he found a Forth image ready-made for the LPC1114. Why is that interesting? The LPC1114 is one of the few (or maybe the only) modern ARM processor in a breadboard-friendly DIP package. Since [Jean-Claude] had a chip sitting around, he had a Forth system up in no time. All he needed was a breadboard and a 3.3V serial connector. The chip has its own bootloader and the The Mecrisp-Stellaris Forth he used has over 300 words as well as the ability, of course, to add more.

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Voice Command With No Echo

August 30, 2015 by 7 Comments

[Naran] was intrigued with the Amazon Echo’s ability to control home electronics, but decided to roll his own. By using a Raspberry Pi with the beta Prota OS, he managed to control some Phillips Hue bulbs and a homebrew smart outlet.

Prota has a speech application, which made the job simpler. He does point out though, that his project doesn’t replace the Echo’s ability to answer questions by searching the Internet. The advantage, though, is it is easily tailored to your specific application. Also, if you have a Raspberry Pi hanging around, you can’t beat the price. Continue reading “Voice Command With No Echo” →

Wii MotionPlus Gyro To Microchip PIC

August 29, 2015 by 3 Comments

Sometimes the most mundane products have surprisingly sophisticated internals. What’s in a game controller? If it is a Wii remote, you’ll find a lot inside–an IR sensor, Bluetooth, an accelerometer, and EEPROM. It also has a six pin expansion port that allows I2C peripherals connect to the controller.

[DotMusclera] wanted to experiment with a gyroscope and decided to hook up to the Wii MotionPlus to a Microchip PIC. Using information from the WiiBrew wiki, [DotMusclera] connected a PIC18F4550, an LCD, and a handful of components (mostly to do 3.3V level conversion), he set up the hardware on a breadboard. The only odd part you might have to work around is a Wii breakout board that converts from the breadboard to the Wii interface.

The software is easy to follow since it is written in Hi-TECH C and well-commented. The hardware lacks a schematic, but from the parts list and the video, you can probably figure it out. The setup works well and shows roll, pitch, and yaw on the LCD screen.

The project log is very detailed, with a lot of information about gyroscopes and the communication format the gyro uses. The video demo is worth watching as well.

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Basically, It’s An ESP8266

August 29, 2015 by 26 Comments

Before the Arduino, there was the Parallax Basic Stamp. It was an easy-to-use PIC chip on a PCB that you programmed in BASIC — a story of those humble beginnings was published earlier this week. Before that, even, legions of small computers from TRS-80s to Commodore 64s and even Altairs were commanded primarily by the BASIC language. BASIC was easy to run on a small machine and very simple to learn. Old fashioned BASICs are difficult to use to write huge systems, but a lot of small computers aren’t going to run very large programs anyway.

The ESP8266 is more than a just a WiFi peripheral for a microcontroller. It is its own little computer in its own right. While it is common to run the “AT” firmware, Lua, or program the device yourself, you can now load the beast with a version of BASIC.

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Reverse Engineering A Different Kind Of Bus

August 27, 2015 by 19 Comments

Radio enthusiasts have a long history of eavesdropping on non-broadcast stations–police, fire, and public transportation frequencies, for example. These days, though, a lot of interesting communications are digital. When [bastibl] wanted to read data displayed on bus stop signs, he turned to software defined radio. He used gr-fosphor to monitor the radio spectrum as buses drove by and discovered a strong signal near 151 MHz (see photo below).

That, however, was just the start. Using a variety of tools, he figured out the modulation scheme, how the data framing worked, and even the error correction scheme. Armed with all the information, he built a GNU Radio receiver to pick up the data. A little number crunching and programming and [bastibl] was able to recover data about  individual buses including their position and schedule.

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