Colorizer For ZX81 Clone

May 20, 2015 by Anool Mahidharia 10 Comments

[danjovic] is a vintage computer enthusiast and has several old computers in his collection. Among them are a couple of TK-85 units – a ZX81 clone manufactured by Microdigital Eletronica in Brazil. The TK-85 outputs a monochrome video output. And when [danjovic] acquired a SyncMaster 510 computer monitor, he went about building a circuit to “colorise” the output from the ZX81 clone (Portuguese translation).

The SyncMaster 510 supports 15kHz RGB video refresh rate, so he thought it ought to be easy to hook it up to the TK-85, which internally has the video and composite sync signals available. So, if he could lower the amplitude of the video signal to 0.7Vpp, using resistors, and connect this signal to one of the primary colors on the monitor, for example green, then the screen should have black characters with a green background.

Before he could do any of this, he first had to debug and fix the TK-85 which seemed to be having several age related issues. After swapping out several deteriorating IC sockets, he was able to get it running. He soldered wires directly to one of the logic chips that had the video and sync signals present on them, along with the +5V and GND connections and hooked them up to a breadboard. He then tested his circuit consisting of the TTL multiplexer, DIP switches and resistors. This worked, but not as expected, and after some digging around, he deduced that it was due to the lack of the back porch in the video signal. From Wikipedia, “The back porch is the portion of each scan line between the end (rising edge) of the horizontal sync pulse and the start of active video. It is used to restore the black level (300 mV.) reference in analog video. In signal processing terms, it compensates for the fall time and settling time following the sync pulse.”

To implement the back porch, he referred to an older hack he had come across that involved solving a similar problem in the ZX81. Eventually, it was easily implemented by an RC filter and a diode. With this done, he was now able to select any RGB value for foreground and background colors. Finally, he built a little PCB to house the multiplexer, DIP switches and level shifting resistors. For those interested, he’s also documented his restoration of the TK-85 over a four-part blog post.

FUBAR Labs Gets A New Space

May 20, 2015 by Brian Benchoff 4 Comments

FUBAR Labs in New Jersey is one of the finest and most productive hackerspaces in the US. They have homebrew rocket engines, the eternal gratitude of semiconductor companies, and a broken Makerbot nailed to the wall: everything a hackerspace should have. Now they’re moving to a new space, and they’re looking for a little funding to turn their lab into what it should be.

There have been a lot of cool builds that have come out of FUBAR Labs including a Power Wheels racer, [Rick]’s Minecraft Circuits In Real Life, the now-obviously named Fubarino, a 3D printed balance bot. a gaseous oxygen and ethanol rocket engine.

Their 890 square foot space was already fantastic, but with a new space that’s 2300 square feet, they’ll be able to expand New Jersey’s finest hackerspace into what it should already be.

The guys at FUBAR put up a gallery of pics of the new space. You can check those out here. Next time Hackaday is in Jersey – or when we forget how to pump our own gas, whatever comes first – we’ll do a hackerspace tour of the new space.

Hackaday Prize Entry: A BeagleBone Logic Analyzer

May 19, 2015 by Brian Benchoff 10 Comments

If you have a BeagleBone, you already have a lot of tools. We’ve seen them used in driving hundreds of LEDs at a very high frame rate, used as a video card for ancient computers, and as a software defined radio. For his entry to The Hackaday Prize, [Kumar] turned his BeagleBone into a 14-channel, 100Msps logic analyzer that’s good enough to debug just about all those hobby electronics projects you’re working on.

The BeagleBone is only able to have this sort of performance as a logic analyzer because of its PRUs, those fancy peripherals that make the Beagle great at blinking pins really, really fast. [Kumar] is using both PRUs in the BeagleBone for this project. PRU1 reads from the input probes, and PRU0 writes all the samples into DDR memory directly. From there, the samples are off to kernel modules and apps, either sigrok, dd, or something you coded up in Python.

Compared to the cheap logic analyzers we have today like the Salae Logic and the DSLogic, [Kumar]’s project is just as good as any commercial offering (provided you can live with 14 channels instead of 16), and because it’s based on a BeagleBone, the software is infinitely expandable.

UPDATE: After this post was written but before it was published, [Kumar] finished up a blog post on how he’s building a logic analyzer with the BeagleBone’s PRUs. It’s a true tutorial, with enough code demos to allow anyone to build their own 8-bit analyzer on a BeagleBone, and there are more updates coming.

The 2015 Hackaday Prize is sponsored by:

“Bricking” Microcontrollers In LEGO Motivates Young Programmers

May 19, 2015 by Bryan Cockfield 15 Comments

Back when he was about seven years old, [Ytai] learned to program on an Atari 800XL. Now he has a seven-year-old of his own and wants to spark his interest in programming, so he created these programmable LEGO bricks with tiny embedded microcontrollers. This is probably one of the few times that “bricking” a microcontroller is a good thing!

The core of the project is the Espruino Pico microcontroller which has the interesting feature of running a Java stack in a very tiny package. The Blocky IDE is very simple as well, and doesn’t bog users down in syntax (which can be discouraging to new programmers, especially when they’re not even a decade old). The bricks that [Ytai] made include a servo motor with bricks on the body and the arm, some LEDs integrated into Technic bricks, and a few pushbutton bricks.

We always like seeing projects that are geared at getting kids interested in creating, programming, and hacking, and this certainly does that! [Ytai] has plans for a few more LEGO-based projects to help keep his kid interested in programming as well, and we look forward to seeing those! If you’re looking for other ways to spark the curiosity of the youths, be sure to check out the Microbot, or if you know some teens that need some direction, perhaps these battlebots are more your style.

[Sophi Kravitz] On Ask An Engineer Tonight

May 19, 2015 by Mike Szczys 9 Comments

Whew, your Wednesday night entertainment is all sorted out. Mark it in your calendar, [Sophi Kravitz] will be appearing on Adafruit’s Ask an Engineer at 8pm EDT (UTC -4).

Of course she’ll be talking about The Hackaday Prize with all of the incredible entries so far and the amazing opportunities waiting for you as THP continues through the summer. But [Sophi’s] life experience runs far-and-deep and so will the conversation. She is an Electronics Engineer, an Artist, and a huge part of the Hackaday crew. This year she landed a grant to bring one of her projects to life for Burning Man (and to document the process which we’re really excited about). She’s brewing up a new project involving Quadcopters and the technology [Alan Yates] has been working on for Valve. And [Sophi] frequently works on projects like Breathe that delight us with her creativity.

But hey, we better leave some of it for the show. The live link is above, here’s the Adafruit page as well.

Continue reading “[Sophi Kravitz] On Ask An Engineer Tonight” →

Raspberry Pis And A Video Triptych

May 19, 2015 by Brian Benchoff 20 Comments

A filmmaker friend of [Thomas] mentioned that she would like to display a triptych at the 2015 Venice Art Walk. This is no ordinary triptych with a frame for three pictures – this is a video triptych, with three displays each showing a different video, and everything running in sync. Sounds like a cool engineering challenge, huh?

The electronics used in the build were three Raspberry Pi 2s and a trio of HDMI displays. Power is provided by a 12V, 10A switching supply with 5V stepdown converters for the Pis. The chassis is a bunch of aluminum bars and U channel encased in an extremely well made arts and crafts style frame. So far, nothing out of the ordinary.

Putting three monitors and three Pis in a frame isn’t the hard part of this build; getting three different displays all showing different videos is. For this, [Thomas] networked the Pis through an Ethernet hub, got the videos to play independently on a RAM disk with omxplayer. One of the Raspberry Pis serves as the master, commanding the slaves to start, stop, and rewind the video on cue. According to [Thomas], it’s a somewhat hacky solution with a bunch of sleep statements at the beginning of the script to allow the boot processes to finish. It’s a beautiful build, though, and if you ever need to command multiple monitors to display the same thing, this is how you do it.

Interview With The Creators Of CHIP, A $9 Single-Board Computer

May 19, 2015 by Mike Szczys 125 Comments

Single-board computing is hot on the DIY scene right now and riding that knife edge is C.H.I.P., a project currently in crowd-funding which prices the base unit at just $9. I was happy to run into the crew from Next/Thing Company who developed C.H.I.P. They were happy because, well, the project’s reception has been like a supernova. Right now they’re at about $1.5M of their original $50k goal. We spoke about running Linux on the board, what connectors and pinout headers are available, as well as the various peripheral hardware they have ready for the board.