Moore’s law isn’t strictly holding anymore, but it is still true that most computing systems are at least trending towards lower cost over time, if not also slightly smaller size. This means wider access to less expensive hardware, even if that hardware is still an 8-bit microcontroller. While some move on to more powerful platforms as a result of this trend, there are others still fighting to push these platforms to the edge. [lcamtuf] has been working to this end, stretching a small AVR microcontroller to not only play a classic video game, but to display it on a color display. Continue reading “Pushing Crates In 8-bit Color”→
It’s always great when we get a chance to follow up on a previous project with more information, or further developments. So we’re happy that [“Ancient” James Brown] just dropped a new video showing the assembly of his Lego brick with a tiny OLED screen inside it. The readers are too, apparently — we got at least half a dozen tips on this one.
We’ve got to admit that this one’s a real treat, with a host of interesting skills on display. Our previous coverage on these bedazzled bricks was disappointingly thin on details, and now the original tweets even seem to have disappeared entirely. In case you didn’t catch the original post, [James] found a way to embed a microcontroller and a remarkably small OLED screen into a Lego-compatible brick — technically a “slope 45 2×2, #3039” — that does a great job of standing in for a tiny computer monitor.
With surface-mount components quickly becoming the norm, even for homebrew hardware, the resistor color-code can sometimes feel a bit old-hat. However, anybody who has ever tried to identify a random through-hole resistor from a pile of assorted values will know that it’s still a handy skill to have up your sleeve. With this in mind, [j] decided to super-size the color-code with “The Great Resistor”.
How the resistor color-code bands work
At the heart of the project is an Arduino Nano clone and a potential divider that measures the resistance of the test resistor against a known fixed value. Using the 16-bit ADC, the range of measurable values is theoretically 0 Ω to 15 MΩ, but there are some remaining issues with electrical noise that currently limit the practical range to between 100 Ω and 2 MΩ.
[j] is measuring the supply voltage to help counteract the noise, but intends to move to an oversampling/averaging method to improve the results in the next iteration.
The measured value is shown on the OLED display at the front, and in resistor color-code on an enormous symbolic resistor lit by WS2812 RGB LEDs behind.
Inside The Great Resistor, the LEDs and baffle plates make the magic work
Precision aside, the project looks very impressive and we like the way the giant resistor has been constructed. It would look great at a science show or a demonstration. We’re sure that the noise issues can be ironed out, and we’d encourage any readers with experience in this area to offer [j] some tips in the comments below. There’s a video after the break of The Great Resistor being put through its paces!
Hearing loss is a common problem for many – especially those who may have attended too many loud concerts in their youth. [mircemk] had recently been for a hearing test, and noticed that the procedure was actually quite straightforward. Armed with this knowledge, he decided to build his own test system and document it for others to use.
Resultant audiogram from the device showing each ear in a different color
By using an Arduino to produce tones of various stepped frequencies, and gradually increasing the volume until the test subject can detect the tone, it is possible to plot an audiogram of hearing threshold sensitivity. Testing each ear individually allows a comparison between one side and the other.
[mircemk] has built a nice miniature cabinet that holds an 8×8 matrix of WS2812 addressable RGB LEDs. A 128×64 pixel OLED display provides user instructions, and a rotary encoder with push-button serves as the user input.
Of course, this is not a calibrated professional piece of test equipment, and a lot will depend on the quality of the earpiece used. However, as a way to check for gross hearing issues, and as an interesting experiment, it holds a lot of promise.
There is even an extension, including a Class D audio amplifier, that allows the use of bone-conduction earpieces to help narrow down the cause of hearing loss further.
Aspiring polyglots can be stymied by differing keyboard layouts and character sets when switching between languages. [Thomas Pollak]’s Poly Keyboard circumvents this problem by putting a screen in every key of the keyboard.
In his extensive build logs, [Pollak] details the different challenges he’s faced while bringing this amazing keyboard to life. For example, the OLED screens need glyph rendering to handle the legends on the keys. Since the goal is true universal language support, he used the Adafruit-GFX Library as a beginning and was able to extend support to Japanese, Korean, and Arabic so far in his custom fork of QMK.
The attention to detail on this build is really impressive. Beside the dedication to full glyph support, [Pollak] has measured the amount of extra force the flex cables from the OLEDs add to the actuation of the keyswitches. For the Gateron yellow switch he tested, the difference was about 62.2 g versus the initial 49.7 g.
In case you’re thinking you’ve seen other screen keyboard projects, [Pollak] includes a roundup of similar projects in his logs as well. This isn’t the first keyboard we’ve seen here at Hackaday with an OLED on top of a keyswitch, although [Voidstar Lab]’s MiRage only has three screen keys that were removed in a later iteration. If you’d like a more conventional fixed display in your keyboard, check out [Peng Zhihui]’s modular board with an e-ink display and haptic feedback knob.
Older hackers will remember that a crystal set radio receiver was often one of the first projects attempted. Times have changed, but there’s still something magical about gathering invisible signals from the air and listening to the radio on a homemade receiver. [mircemk] has brought the idea right up to date by building an FM radio with an OLED display, controlled with a rotary encoder.
The design is fairly straightforward, based as it is on another project that [mircemk] found on another site, but the build looks very slick and would take pride of place on any hacker’s workbench. An Arduino Due forms the heart of the project, controlling a TEA5767 module, an SH1106 128×64 pixel OLED display and a rotary encoder. The sound signal is passed through an LM4811 headphone amplifier for private listening, and a PAM8403 Class D audio amplifier for the built-in loudspeaker. The enclosure is made from PVC panels, and accented with colored adhesive tape for style.
It’s easier than ever before to quickly put together projects like this by connecting pre-built modules and downloading code from the Internet, but that doesn’t mean it’s not a worthwhile way to improve your skills and make some useful devices like this one. There are so many resources available to us these days and standing on the shoulders of giants has always been a great way to see farther.
For prototype electronics projects, most of us have a pile of resistors of various values stored somewhere on our tool bench. There are different methods of organizing them for easy access and identification, but for true efficiency a resistance substitution box can be used on the breadboard to quickly change resistance values at a single point in a circuit. Until now it seemed this would be the pinnacle of quickly selecting differently-sized resistors, but thanks to this programmable resistor bank there’s an even better option available now.
Unlike a traditional substitution box or decade box, which uses switches or dials to select different valued resistors across a set of terminals, this one is programmable and uses a series of sealed relays instead. That’s not where the features stop, though. It also comes equipped with internal calibration circuitry which take into account the resistance of the relay contacts and internal wiring to provide a very precise resistance value across its terminals. It’s also able to be calibrated manually to account for temperature or other factors.
For an often-overlooked piece of test equipment, this one surely fits the bill of something we didn’t know we needed until now. Even though digital resistor substitution boxes are things we have featured in the past, the connectivity and calibration capabilities of this one make it intriguing.
