The Difference Between Bitcrushers And Sample Rate Reducers

August 25, 2013 by 23 Comments

bit

If you look around a few electronic music forums, you’ll see a lot of confusion over the difference between a bitcrusher – a filter that reduces the bit depth of an audio signal – and a sample rate reducer – a filter that does exactly what its name implies. With the popularization of 8-bit and retro synth music, this difference is obviously of grave import of concern to saints and kings alike. [Michael] is more than happy to walk us through the difference with real-time sample and bit rate adjustment with his audio hacker board.

The audio hacker board is an Arduino shield with a 12-bit DAC and a 12-bit ADC. With two 1/8″ jacks and a pair of pots, [Michael] was easily able to whip up a sketch that is able to adjust the sample rate and bit depth of an audio signal in real-time.

Contrary to nearly everyone’s opinion of what ‘8-bit’ music is, it’s actually the sample rate that makes music sound like a cassette deck jury rigged into a Nintendo Entertainment System. Reducing the bitrate just makes any audio source sound louder and worse.

Check out the excellent demo video of the effect of bitcrushers and sample rate reducers below.

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The Straddler Makes AVR Breadboarding Truly Plug And Play

August 25, 2013 by 17 Comments

the_straddler_avr_programmer

It’s not that breadboarding AVR circuits is difficult. But you have to admit that it takes some time to set everything up. We don’t label the top of our DIP chips so that you know what each pin does just by looking. Which means that wiring up the programmer involves pulling out the datasheet. [Vinnie] found the solution to this problem which is to make one of these interface PCBs for each AVR chip family. The long pins make it easy to drop over the top of your microcontroller, which is where the name comes from.

His first stab at the idea was just a hunk of home etched PCB which broke out the programming pins into the 6-pin ICSP standard. This second rendition uses the 10-pin standard and adds a few extras into the mix. He included decoupling capacitors which need to be used in every circuit anyway. There’s a crystal along with its load capacitors. This clock source is a snap to enable by burning some fuses. If you choose to use the internal oscillator instead this hardware won’t interfere. The LED is used to get you up and running with blinky firmware as quickly as possible. He plans to add jumper in the next revision which can disconnect this components from the I/O pin. Now you just need to add a 10-pin header to that USB keyboard AVR programmer and you’re in business.

Making Keys After The Apocalypse

August 25, 2013 by 50 Comments

Making keys is an amazing art with a lot of skill and technique involved. For those of you living in a post-apocalyptic world, [Dan] has a much simpler solution to the problems of having one too few keys for your locks and deadbolts – just cast them out of scrap with the power of the sun.

To make the mold of the key, [Dan] is using a two-piece plaster of paris mold. First, a thick layer of plaster is laid down in a small container and the key floated on the surface. After drying, sprues are put in with clay and the key embedded in a curing plaster block. After a few hours, a proper mold is created ready to receive molten metal.

The casting material is zinc – not as hard as the original steel key, but more than strong enough to turn a lock. This zinc is melted in a steel and plaster crucible with a gigantic fresnel lens.

As for the utility of this method of copying keys after the apocalypse, we’ll have to wonder how practical this method is. A giant fresnel lens isn’t just something you randomly find unless you’re going house to house looking for projection TVs, and finding a can of mold release after the end of the world is beyond credulity. That said, it’s a cool demonstration of metal casting that can be easily accomplished at home or at any hackerspace.

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Connecting An Old Scope To A Computer

August 25, 2013 by 21 Comments

Scope

A friend of [Michael]’s said his company was getting rid of some old lab equipment and asked him if he wanted a very large and very old digital storage oscilloscope. A ‘hell yes’ and we’re sure a few beers later, [Michael] found an old Gould 200 MHz four-channel scope on his bench. Even 20 years after its production it’s still a capable tool, but the serial ports on the back got [Michael] wondering – would it be possible to plot the screen of the scope on his computer?

The scope has three ports on the back – GPIB, miscellaneous I/O, and RS423. The latter of those ports is similar enough to RS232 that a USB to Serial converter just might work, and with the help of a null modem cable and a terminal, [Michael] was able to connect to this ancient scope.

In the manual, [Michael] found a the serial commands for this scope. The most useful of these is a command that prints out the contents of the scope’s trace memory as a series of 1-byte integers. With a short bit of PERL programming, [Michael] can create a PDF plot of whatever is on the scope’s screen. It’s formatted perfectly for Gnuplot, MATLAB, or even Excel.

Awesome work, and especially useful given these old scopes are slowly making their way to a technological boneyard somewhere.

Turning Cheap Voltmeters Into I2C Displays

August 25, 2013 by 7 Comments

Voltmeter I2C Displays

[Tom] needed 8 displays for a project. He wanted to to control them over I2C, and was trying to reduce cost. Some vendors make I2C controllable seven segment displays, but they cost about $10 each. [Tom] figured he could hack cheap voltmeters to get the same results for about $3 a pop.

The voltmeters that [Tom] bought used a 8 bit STM8S003F3P6 microcontroller. He reverse engineered the device and re-created the schematic to find out where the I2C and programming pins would be. Then he hooked it up to a STM8 Discovery development board, which has an integrated programmer.

With the hardware figured out, it was time for new firmware. Fortunately, [ba0sh1] had already written firmware for a similar purpose which could easily be adapted. The code implements a software I2C slave, which reads data off the bus and displays it. It’s all available on Github.

The end result is a I2C controlled display for a third of the cost. Next time you need a bunch of these in a project, consider picking up some cheap voltmeters.

Building An Audio Box Out Of Thrown Away Boards

August 24, 2013 by 9 Comments

The last time [Mark] was at the scrap yard, he managed to find the analogue input and output cards of an old Akai DR8 studio hard drive recorder. These cards offered great possibilities (8 ADC inputs, 12 DAC outputs) so he repaired them and made a whole audio system out of them.

The repair only involved changing a couple of low dropout regulators. Afterwards, [Mark] interfaced one of his CPLD development boards so he could produce some sine waves and digitize signals generated from a PC based audio test unit. He then made the frame shown in the picture above and switched to an Altera Cyclone IV FPGA. To complete his system, he designed a small board to attach a VGA screen,  and another to use the nRF24L01 wireless module.

Inside the FPGA, [Mark] used a NIOS II soft core processor to orchestrate the complete system and display a nice user interface. He even made another system with an USB host plug to connect MIDI enabled peripherals, allowing him to wirelessly control his creation.

75 Controllers, One Gaming System

August 24, 2013 by 14 Comments

Multi Video Games System

This gaming cabinet lets two players select games from a wide array of consoles and play them using the original controllers. [Patrice] built it around his Multi Video Games System 2, which converts each of the 75 controllers to a common format. Players pick controllers from the display case, plug in an  HD-15 connector, and choose the game they want to play. The cabinet contains a PC that runs a variety of emulators, and uses HyperSpin as a menu system.

Using adapters, the converted controllers can also be used on other game systems, tablets, or smartphones. [Patrice] claims that they’ll work across 110 different game systems. A full list of the controllers and systems is shown here.

This cabinet is definitely one of the most comprehensive video game installations we’ve seen, and the display case of controllers looks fantastic. Check out a video of the system and some controller porn after the break.

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