L.I.O.S.: The Ten-ish Dollar Robot.

October 1, 2012 by Jesse Congdon 10 Comments

We love cheap stuff here. Who doesn’t? [Oscar Rodriguez Parra] does too, and wrote in to show us his super cheapey robot L.I.O.S. The build was for the AFRON design challenge, which involves building a 10 dollar robot to teach students robotics. The winners of the challenge were neat and all, but they all look too fancy flaunting their molded plastics and electronics breadboards.

[Oscar’s] design is super simple, LDRs as eyes, a PIC12F683 to do the brainin, LEDs for indicators and a couple modded servos to drive the wheels. An extraordinarily complex cardboard flap roller helps the cart turn, but probably isn’t going to see much aside from smooth flooring. The electronics are mounted using one of our favorite techniques, the paper perf board (very similar to the substrate free technique).

Check out the video after the jump to see LIOS in action. This is an excellent introduction to robotics for any classroom. Thanks [Oscar]!

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Test Your Project’s Mettle With A Protected Dummy Load

October 1, 2012 by Jesse Congdon 2 Comments

For a power hungry project the supply is sometimes a pretty big unknown. Whether stapling together a few different power supplies to meet a current requirement, or designing a system from the ground up: a big power supply can be quite a dangerous thing. It helps to have some kind of a dummy load to really shake down the electronics and get an idea of how hot things get or test stability before trusting the supply to run your stuff. [Paulo Oliveira] has constructed just such a thing, a slick looking adjustable constant current load.

Following the popular LM324 circuit from [David Jones] at EEVblog [Paulo] decided to make use of the two spare op-amps to provide both a thermal overload and a cooling fan circuit. We have seen other tweaks to [David]’s circuit in the past but through some resistors and MOSFETs [Paulo] can now load up to 7A (limited by resistor wattage). We would have used a really crazy server ~~vacuum~~ fan to make it genuinely frightening to push heavier loads. Thanks [Paulo]!

Beginner’s Look At On-Chip Debugging

September 27, 2012 by Mike Szczys 20 Comments

As your embedded applications get more complicated an On-Chip Debugger will save you a lot of time when things don’t run quite right. On-Chip Debugging (OCD) is just what it sounds like — a way to run your program on the target chip that lets you pause execution to examine values and change them if need be. The Arduino has no built-in method of using OCD, but the AVR chips used by the boards do. The caveat is that you need a proper AVR programmer to access the Debug Wire protocol, or a JTAG interface for some of the larger chips. In this case I’m going to be using an STM32 Discovery Board to give you an overview of OCD. But this will work the same way for any chip that has hardware debugging capabilities. Many IDE’s have debugging support built right in so that you can use a nice GUI as you work. But often these are just a front end for the command line tools I’ll be using. Join me after the break and we’ll get started.

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Adding Famicom Audio Channles To An NES Without Messing Up The Console

September 22, 2012 by Jesse Congdon 25 Comments

[Callan Brown] wrote in to show us a really interesting NES audio hack. [Callen] decided that he wanted the full Castlevania III audio experience, which (without modifications) can only be had through the original Japanese Famicom console. [Callen] weighed a few adapter options, and instead decided to come up with his own.

The issue is that the Japanese Famicom and the American NES actually have a different cartridge connector. The change in hardware from a 60 pin to a 72 pin connector added “features” like the 10 pins connected directly to the expansion port (used for stuff like the teleplay modem, who knew). The other two additional pins are used by the annoying 10NES lockout chip. While they were at it, Nintendo decided to route the audio path through the expansion connector instead of the cartridge.

This means that the Japanese cartridges can’t pipe sound to the NES audio channel with just a pin adapter. Good news though, after sourcing a pin adapter hidden inside certain NES games (Stack Up, Gyromite), audio can easily just be pulled from the adapter PCB. This requires the more expensive Famicom Castlevania III cartridge (Akumajou Densetsu). To cleanly route the new audio cable out of his front loading NES [Callan] reuses the sacrificial adapter game’s cart to make some kind of unholy hybrid. To round it off [Callan] also goes over steps to flash a translated ROM to the Japanese game.

What difference could an extra two squares and a sawtooth make? Check out the sound comparison video after the jump! Thanks [Callan].

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Another Eerily Similar High Power LED Driver Hack

September 20, 2012 by Jesse Congdon 1 Comment

[Maximilian Güntner] dropped us a comment in last week’s globe writeup linking to his own project, which involves a similar high power LED driver mod. This looks like the exact same mod we came up with, and [Güntner] even used the mod to connect a bunch of high power LEDs to a PCA9685 LED driver [pdf]. It’s the same exact concept as Disco Planet!

It should come as no surprise that people have actually been modding high power led drivers in this way for some time. They are a few bucks per handful and take an enormous input voltage range. In [Güntner]’s case he grabbed a bunch of these from Dealextreme. Actually there are two others on the site, and all three contain comments (dating back a year) with helpful tips on various ways to modify the little PCB.

Our Ebay sourced boards are different though. The boards [Güntner] purchased employ the PowTech PT4115 [pdf] which uses fewer parts and has an easy to follow data sheet. Take, for instance, the pin graciously labeled “DIM” with a little PWM signal next to it. The nerve! The Ebay drivers use the MCP34063 [pdf] which has a much more cryptic data sheet (burned two weeks and several notebook pages to figure out the circuit). Ultimately the two are so similar it makes no difference.

So, if you want to mod some LED drivers on your own, check out the how-to video after the jump. Thanks [mguentner]!

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DIY Flanagan Neurophone Lets You Hear With Ultrasound

August 7, 2012 by Jesse Congdon 85 Comments

[Andreas] wrote in to let us know about this DIY Neurophone project. Apparently a Flanagan Neurophone uses ultrasound in some manner to transmit audio directly to the body, or nervous system? Needless to say we are a bit skeptical of anyone whose wiki page leads directly to pyramid power. In fact most of the references to this thing start rambling about some pretty pseudo-scientific theories.

At any rate, the schematic is clear and simple enough for anyone who has the parts to easily try. The only challenge might be tuning the thing with a signal generator or audio feed. So how about it, any one have a TL494 pulse-width modulation controller and want to be a guinea pig?

Using An IR Remote With Your Arduino

July 23, 2012 by Brian Benchoff 9 Comments

If you’ve ever needed a short-range remote control for a project, [firestorm] is here to help you out. He put up a great tutorial on using an IR remote to do just about anything with everyone’s favorite microcontroller platform.

[firestorm] used the Arduino IRremote library to decode the button presses on his remote. After uploading the IR receive demo included in the library, the Arduino spit out hex codes of what the IR receiver was seeing. [firestorm] wrote these down, and was able to program his Arduino to respond to each individual button press.

After figuring out the IR codes for his remote, [firestorm] threw a shift register into his bread board and attached a seven-segment LED. Since [firestorm] knows the codes for the number buttons on his remote, it’s very easy to have the LED display flash a number when the corresponding button on the remote is pressed.

A single seven-segment display might not be extremely useful, but with [firestorm]’s tutorial, it’s easy to give your Arduino some remote control capabilities with a simple IR receiver. Not bad for a few dollars in parts.