MicroVox driven by Arduino Uno

MicroVox Puts The 80’s Back Into Your Computer’s Voice

[Monta Elkins] got it in his mind that he wanted to try out an old-style speech synthesizer with the SC-01 (or SC-01A) chip, one that uses phonemes to produce speech. After searching online he found a MicroVox text-to-speech synthesizer from the 1980s based around the chip, and after putting together a makeshift serial cable, he connected it up to an Arduino Uno and tried it out. It has that 8-bit artificial voice that many of us remember fondly and is fairly understandable.

The SC-01, and then the SC-01A, were made by Votrax International, Inc. In addition to the MicroVox, the SC-01 and SC-01A were used in the Heath Hero robot, the VS-100 synthesizer add-on for TRS-80s, various arcade games such as Qbert and Krull, and in a variety of other products. Its input determines which phonemes to play and where it shines is in producing good transitions between them to come up with decent speech, much better than you’d get if you just play the phonemes one after the other.

microvox-manualThe MicroVox has a 25-pin RS-232 serial port as well as a parallel port and a speaker jack. In addition to the SC-01A, it has a 6502 under the hood. [Monta] was lucky to also receive the manual, and what a manual it is! In addition to a list of the supported phonemes and words, it also contains the schematics, parts list and details for the serial port which alone would make for fun reading. We really liked the taped-in note seen in this screenshot. It has a hand-written noted that says “Factory Corrected 10/18/82”.

Following along with [Monta] in the video below, he finds the serial port’s input buffer chip datasheet online and verifies the voltage levels. Next he opens up the case and uses dips switches to set baud rate, data bits, parity, stop bits and so on. After hooking up the speakers, putting together a makeshift cable for RX, TX and ground, and writing a little Arduino code, he sends it text and out comes the speech.

Continue reading “MicroVox Puts The 80’s Back Into Your Computer’s Voice”

Interview: Nacer Chahat Designs Antennas For Mars CubeSats

You have a shoe box sized computer that you want to use in a Mars fly by. How do you communicate with it? The answer is a very clever set of antennas. I got to sit down with Nacer Chahat, one of the engineers on the Jet Propulsion Laboratory team responsible for antenna design on Mars Cube One (MarCO). Two of these CubeSats that will soon be used to help a lander reach Mars. We talked about the work that went into MarCO, the deployable radar antenna he’s worked on for the RainCube project, and the early progress on OMERA, the One Meter Reflectarray.

This is a fascinating discussion of dealing with a multitude of engineering challenges including lack of available space for the antenna components, and power and weight limitations. Check out the video interview to see how the people at JPL fit it all into this, and other tiny satellites, then join us below for more details.

Continue reading “Interview: Nacer Chahat Designs Antennas For Mars CubeSats”

T-Rex Runner Runs On Transistor Tester

If you’ve ever spent time online buying electronic doodads — which would mean almost all of us — then sooner or later, the websites get wind of your buying sprees and start offering “suggested” advertisements for buying more useless stuff. One commonly offered popular product seems to be a universal component tester, often referred to as a “Mega328 Transistor Tester Diode Triode Capacitance ESR Meter”. These consist of an ATmega328, an SPI LCD display, a Button, a ZIF socket and a few other components. Almost all of them are cheap clones of the splendid AVR-TransistorTester project by [Markus Frejek]. [Robson Couto] got one of these clone component testers, and after playing with it for a while, decided to hack it and write a T-Rex runner game for it.

The T-Rex runner game is Chrome’s offering for you to while away your time when it can’t connect to the internet. It needs just one button to play. This is just the kind of simple game that can be easily ported to the Component Tester. The nice take away from [Robson]’s blog post is not that he wrote a simple game for an ATmega connected to an LCD display, but the detailed walk through he provides of the process which can be useful to anyone else wanting to dip their feet in the world of writing games.

After a bit of online sleuthing and some multimeter testing, he was able to figure out that the LCD controller chip was connected to Port D of the ATmega, which meant the use of software SPI via bit-banging. He then looked inside the disassembled firmware to find writes to Port D to figure out pin assignments. Of course not long after all this work he found a config.h file with the pin mappings.

Armed with this information he was able to use the Adafruit ST7565 library to drive the LCD, but not before having to flip the image. The modified fork of his ST7565 library is available on GitHub. His game code is also available, but reading through the development process is pretty interesting. Check out a video of the Runner game in action after the break.

In an earlier post, we did a product review of one of these cheap Transistor Testers, and if you have one of these lying around, give [Robson]’s game a spin — it could be handy while you wait for your reflow oven to finish its soldering cycle.

Continue reading “T-Rex Runner Runs On Transistor Tester”

Moving Microns With A High Precision Linear Stage

As anyone who has experimented with their own home-made CNC machinery will tell you, precision isn’t cheap. You can assemble a gantry mill using off-the-shelf threading and kitchen drawer slides. But it’s a safe assumption that if you put the tool at a particular position it won’t be quite at the same position next time you return. But if you take your budget from dirt cheap to reasonably priced you can do much better. [Adam Bender] designs high-precision automation systems for a living, so when he needed a precision linear stage for a personal project he achieved micron level accuracy for under $500.

micron-precision-linear-actuator
Red parts are the two spring-loaded nuts

He explains the problem of backlash with an inexpensive lead screw — the wiggle between threaded components that cause positional chaos. His solution uses two nuts preloaded against each other with a spring. There is still a stick-slip issue; a tendency to move in lurches due to differences between the coefficients of static and dynamic friction between the materials. Careful choice of machining stock for the nut to picking materials in which these coefficients were almost identical reduced the stick-slip to as little as possible.

He goes into significant detail on the design, manufacture, and testing of all the components of his stage, its body, sealing system, and control. If you are a precision CNC guru maybe you’ll find it interesting as a cleverly designed component, but if you are a mere dilettante you’ll find it fascinating to read a comprehensive but accessible write-up from a professional in the field.

This build probably goes a step beyond most we’ve featured in the past, but that’s not to say we’ve not seen some pretty good efforts.