[Fran]’s LEDs, Nixies, And VFDs.

January 4, 2014 by Brian Benchoff 21 Comments

With a love of blinky and glowey things, [Fran] has collected a lot of electronic display devices over the years. Now she’s doing a few teardowns and tutorials on some of her (and our) favorite parts: LEDs and VFD and Nixie tubes

Perhaps it’s unsurprising that someone with hardware from a Saturn V flight computer also has a whole lot of vintage components, but we’re just surprised at how complete [Fran]’s collection is. She has one of the very first commercial LEDs ever made. It’s a very tiny red LED made by Monsanto (yes, that company) packaged in a very odd lead-and-cup package.

Also in her LED collection is a strange Western Electric part that’s green, but not the green you expect from an LED. This LED is more of an emerald color – not this color, but more like the green you get with a CMYK process. It would be really cool to see one of these put in a package with red, green, and blue LED, and could have some interesting applications considering the color space of an RGB LED.

Apart from her LEDs, [Fran] also has a huge collection of VFD and Nixie tubes. Despite the beliefs of eBay sellers, these two technologies are not the same: VFDs are true vacuum tubes with a phosphorescent coating and work something like a CRT turned inside out. Nixies, on the other hand, are filled with a gas (usually neon) that turns to plasma when current flows through one of the digits. [Fran] has a ton of VFDs and Nixies – mostly military surplus – and sent a few over to [Dave Jones] for him to fool around with.

It’s all very cool stuff and a great lead-in to what we hear [Fran] will be looking at next: electroluminescent displays found in the Apollo Guidance Computer.

Videos below.

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Build An Audio Spectrum Analyzer The Analog Way

January 3, 2014 by Adam Fabio 18 Comments

bandpass

[Ryan] wanted a spectrum analyzer for his audio equipment. Rather than grab a micro, he did it the analog way. [Ryan] designed a 10 band audio spectrum analyzer. This means that he needs 10 band-pass filters. As the name implies, a band-pass filter will only allow signals with frequency of a selected band to pass. Signals with frequency above or below the filter’s passband will be attenuated. The band-pass itself is constructed from a high pass and a low pass filter. [Ryan] used simple resistor capacitor (RC) filters to implement his design.

All those discrete components would quickly attenuate [Ryan’s] input signal, so each stage uses two op-amps. The first stage is a buffer for each band. The second op-amp, located after the band-pass filters, is configured as a non-inverting amplifier. These amplifiers boost the individual band signals before they leave the board. [Ryan] even added an “energy filler” mode. In normal mode, the analyzer’s output will exactly follow the input signal. In “energy filler” (AKA peak detect) mode, the output will display the signal peaks, with a slow decay down to the input signal. The energy filler mode is created by using an n-channel FET to store charge in an electrolytic capacitor.

Have we mentioned that for 10 bands, all this circuitry had to be built 10 times? Not to mention input buffering circuitry. With all this done, [Ryan] still has to build the output portion of the analyzer: 160 blue LEDs and their associated drive circuitry. Going “all analog” may seem crazy in this day and age of high-speed micro controllers and FFTs, but the simple fact is that these circuits work, and work well. The only thing to fear is perf board solder shorts. We think debugging those is half the fun.

Reverse Engineering HitClips

January 1, 2014 by Brian Benchoff 31 Comments

hitclipz

After a quick review of the Hackaday viewer demographics, we need to say the late 90s were weird. Even portable audio players were downright bizarre: MP3 players existed, but you loaded up your songs (all eight of them) over your PC’s parallel port. While helping a cousin move some furniture, [Ch00f] found a huge collection of one of the oddest music formats ever: HitClips, a tiny plastic encapsulated bit of circuitry that stores 60 seconds of terrible-sounding mono audio. Yes, this was a thing, but so was the pet rock. With no HitClips player, [Ch00f] decided he would take a swing at reverse engineering these tiny, tinny songs.

After taking apart the plastic enclosure, [Ch00f] found a very simple circuit: a few resistors, a cap, and an epoxy blob that enclosed an die with the musical data. On the back of the clip, there are eight pads for connecting to the player. With nothing to go on, [Ch00f] started poking around and found connecting one of these pins to ground caused circuit to draw 300uA of current for about 60 seconds – the same length of time as the recorded sample.

[Ch00f] originally thought the HitClip would provide audio data over an SPI or other digital protocol. What he found was much more interesting: two of the pins on the HitClip correspond to the push and pull FETs of a class D amplifier. The audio on the HitClip is digital audio, but it’s encoded so it can directly drive an analog circuit. Pretty clever engineering for a happy meal toy, if you ask us.

After dumping this data with a logic analyzer, [Ch00f] turned all the values in to .WAV file. It was, amazingly, music. A little refinement to the process to nail down the timing resulted in a 60-second clip seen (heard?) after the break.

Since [Ch00f] doesn’t want to spend $40 on eBay for a vintage HitClips player, he’s right about at the limit of what he can reverse engineer out of these cheap, crappy music chips. He has put up all his documentation, though, so if you’re up for improving on [Ch00f]’s methods, have a go.

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Fubarino Contest: Splash Screen On System Reset

December 29, 2013 by Brian Benchoff 3 Comments

Here’s a Fubarino contest entry for all those homebrew computer nuts out there. [Danjovic] modified an NTSC/PAL display adapter to show an ASCII version of the Hackaday logo when his board first boots up.

The build is based on [Daryl Rictor]’s Video Display Adapter intended for use with homebrew computers, microprocessor projects, and any other minimalist digital setup that needs an NTSC or PAL video display. It’s a surprisingly simple circuit, made of a few logic ICs and an ATmega8.

[Danjovic] modified this video display adapter with an easter egg: if one pin on the ATmega8 is shorted when the board is powered on, a neat Hackaday splash screen is displayed for several seconds before falling back to the stock display of a blinking cursor. [Dnajovic] converted the ASCII Hackaday logo with the help of a short Python script and loaded it onto the AVR with a small firmware change.

Video of the boot screen in action below.

This is an entry in the Fubarino Contest for a chance at one of the 20 Fubarino SD boards which Microchip has put up as prizes!

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Apple And Raspberry Pis

December 26, 2013 by Brian Benchoff 22 Comments

A2Pi

Deep in the bowels of the Internet there are some crazy people who have a wish list for what the next Apple II should look like. The capabilities of this dream machine of 80s retrocomputing is generally said to be something with a 32-bit CPU, a UNIX OS, modern graphics, and networking. This sounds a lot like a Raspberry Pi, so [Dave] built an Apple II to Raspberry Pi adapter card.

Having a Pi talk to an Apple II over a serial connection doesn’t really give either machine the full capabilities of the other. To fix this issue, [Dave] wrote two pieces of software. The first is a UNIX daemon that listens to the Apple II on a serial port connection, handling the Apple II keyboard connection. The second piece of software is a ProDOS disk image file running on the Apple II. With these two pieces of software, [Dave] can run the Apple on the Raspi, or run the Raspi on the Apple, sending files and data back and forth with no problem.

Aside from providing a strange and awesome Apple II to UNIX interface, the Apple II Pi also has a lot of advantages that might not be readily apparent. An Apple II compact flash adapter can be used as an internal hard drive for these pieces of classic apple hardware, and the Uthernet Ethernet card for the AII brings networking. Both of these devices are absurdly expensive compared to the component cost of the Apple II Pi, and what they bring to the table can be easily copied by the Apple II Pi.

The Apple II Pi is just a simple double-sided board with a few resistors, a cap, header, a 7404 inverter, and a communications chip that’s $5 for quantity one. If you already have a Raspi hanging around your workbench and want to soup up an Apple II with some crazy hardware capabilities, you really can’t do better than getting one of these Apple II Pi boards. Now if we could only find the board files…

Video of the Apple II Pi below, showing off all the awesome capabilities of a Pi-powered Apple. Thanks [Itay] for sending this one in.

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Further Teardown Of The Saturn V Flight Computer

December 16, 2013 by Eric Evenchick 23 Comments

[Fran] has been working on tearing down and reverse engineering the Saturn V Launch Vehicle Digital Computer (LVDC). In her finale, she’s succeeded in depotting the legacy components while keeping them intact.

She accomplished this by carefully removing the silicone compound using a gum brush. This was a laborious process, but it allowed her to see the device’s innards. With this knowledge, she could recreate the logic modules on a breadboard.

[Fran]’s work on the LVDC has been very interesting. It began with a look at the PCB, followed by an x-ray analysis. Next up was a three part series of the teardown. With each part is a detailed video on the progress.

While this is the end of [Fran]’s work on the project, she will be handing off the LVDC hardware to another engineer to continue the analysis. We’re looking forward to seeing what comes out of this continued research.

Reverse Engineering An LCD Display

December 14, 2013 by Phillip Ryals 31 Comments

The current marketplace allows hobbyists to easily find inexpensive, well-documented displays, but what if you wanted to interface with something more complicated, such as the screen on an iPod Nano 6? [Mike] has given us a detailed and insightful video showing his process for reverse engineering a device with little-to-no documentation. Here he covers the initial investigation, where one scours the web in search of any available information. In [Mike’s] example, the display uses an MIPI D-PHY interface, which he has never worked with. He learns that the MIPI Alliance will provide design specs in exchange for a signed NDA (Non-Disclosure Agreement) and a modest $8000 fee. Nice.

[Mike] shows off some serious hardware hackery, tackling some extremely difficult soldering in order to set up a proper test platform. He then demonstrates how to use a rather awesome oscilloscope to better understand the display protocol. We found it fascinating to see the video signals displayed as waveforms, especially when he shows how it is possible to count the individual binary values. The amount of information he uncovers with the oscilloscope is nothing short of amazing, proving these little devices are more complex than they seem.

[via Hacked Gadgets]

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