ATtiny controlled magic eye tube

In the early days of broadcast radio, the most expensive radio sets were extremely impressive pieces of furniture. With beautifully crafted wooden cases polished to a high shine, these wireless receivers were the focal point of any family room. Some of the most expensive radio sets even included a visual indicator signaling the strength of the reception, something [Marcus] decided to re-engineer using an ATtiny85.

The display tube in question is an EM800 magic eye tube, used in radio sets, stereos, and electronic test equipment as a rudimentary display indicator. By applying a control voltage (from 0 to -10V), the illuminated display can be controlled like a bar graph display.

[Marcus]‘ tube display is built around an ATtiny85 microcontroller, using a homemade PCB. It’s a fairly simple build, once the issue of supplying 250 Volts to the EM800′s anode is taken care of.

In the video after the break, you can see the bar display of [Marcus]‘s magic eye tube slowly growing and receding, perfect for either displaying the current CPU load on your computer or anything else a dynamic bar graph display would be used.

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70 watt amp uses an ATtiny

If you’re looking for a DIY amplifier project made with a minimum of parts, this is the build for you. [Rouslan] created a 70 watt class D amplifier using an ATtiny45 and just a few dollars worth of additional components.

A class D amplifier simply switches transistors of MOSFETs on and off very rapidly. By passing the signal produced by these MOSFETs through a low pass filter and connecting a speaker, a class D amp is able to amplify a signal very efficiently. Usually, these sort of amp builds use somewhat esoteric components, but [Rouslan] figured out how to use a simple ATtiny microcontroller to drive a set of MOSFETs.

In [Rouslan]‘s circuit, the audio signal is passed into the analog input of an ATtiny45. Inside this microcontroller, these analog values are sent to the MOSFETs through a PWM output. [Rouslan] threw in a few software tricks (explained in revision 2 of his build) to improve the sound quality, but the circuit remains incredibly simple.

[Rouslan] posted a video going over the function of his ATtiny amp, and from the audio demo (available after the break), we’re thinking it sounds pretty good. Amazingly good, even, if you consider how minimalistic this 70 watt amp actually is.

Thanks [Alec] for sending this one in.

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Turning on PC speakers whenever there is music playing

If you’re like a lot of people, most of the time your computer speakers are on without actually playing any music. This wastes a bit of power, and [Bogdan] thought he could create a circuit to cut down on that wasted electricity. The result is a very tiny auto-on circuit able fit inside a pair of speakers.

The circuit is built around the ATtiny13, very nearly the smallest microcontroller available with an on-board ADC. When music is played on the computer, the ATtiny senses a bit of voltage in the audio line and switches a relay to power the speaker.

Of course, there is always the problem of music with a high dynamic range; if the sound played from the computer has too low of a volume, the ATtiny might turn the speakers off even if music is playing. [Bogdan] solved this problem by adding a timer to his code; if nothing is detected by the ADC for three minutes, the speakers turn off.

Learning the ins and outs of USB with a simple dev board

We can’t count the number of projects we’ve seen on Hackaday with a USB port.  Unfortunately, most of these builds – from RepRap controllers to wireless data loggers – don’t use the full capabilities offered to them with USB. [Ben] came up with a very cool USB breakout board that allows you to explore the USB protocol with just a single inexpensive ATtiny.

Instead of relying on an FTDI chip or otherwise sending serial data down a USB pipe, [Ben]‘s project is meant to be the hardware compliment to his book on programming USB devices. His hardware board is exceedingly simple, just an ATtiny 2313, a USB port, and a handful of other components, but allows [Ben] to receive data on eight pins on a breadboard and send them over USB to a computer.

[Ben] had sent in his USB figure eight controller, a board that displays the numbers 0 through 9 according to what data is received via USB, a while ago. It’s a truly useless build aside from learning how USB works, but an excellent tool if you’d like to program your own USB device.

Programming the ATtiny10 with an Arduino

The ATtiny10 – along with its younger siblings that go by the names ATtiny 4, 5, and 9 – are the smallest microcontrollers Atmel makes. With only 32 bytes of RAM and 1 kB of Flash, there’s still whole lot you can do with this tiny six-pin chip. [feynman17] figured out a way to program this chip using an Arduino, allowing him to throw just about anything at this absurdly small microcontroller.

The ATtiny10 doesn’t use the familiar ISP programming header found on other Atmel-based boards. Instead, it uses the exceedingly odd Tiny Programming Interface to write bits to the Flash on the chip. [feynman17] realized he could use the Arduino SPI library to communicate with this chip and built a small programming shield with just a few resistors and a 8-pin DIP socket to mount an ATtiny10 breakout board.

After writing a sketch to upload a .hex file from the Arduino serial console, [feynman] had a programmed ATtiny10, ready to be dropped into whatever astonishingly small project he had in mind.

As for what you can do with this small microcontroller, chiptunes are always an option, as is making a very, very small Simon clone. It may not be a powerhouse, but there’s still a lot you can do with this very inexpensive microcontroller.

Genezap improves your video game skills using corporal punishment

genezap

As if getting your ass handed to you while playing video games wasn’t annoying enough, [furrtek] decided that the best way to help improve his skills was by inflicting physical pain each time his on-screen character died.

While perusing the Internet looking for something to break through the doldrums of the day, he came upon a video in which someone decided to try on a dog shock collar just for kicks. This sparked [furrtek’s] imagination, and he started to think that it would be pretty cool to use the same sort of device to make dying in a video game that much more unpleasant.

After ordering a set of collars online, he tore them apart to see how they functioned, and to measure just how big of a jolt they were able to deliver. [furrtek] then modified two Genesis controllers with a pair of ATtiny 25s, which let him send the fire signal to the collars. Unfortunately, stock Genesis games don’t allow you to send signals to the controllers, so [furrtek] had to spend some time hacking ROM images to trigger events when players are injured or lose a life.

We think the project is pretty slick, and if you don’t mind fiddling with your old controllers, you too can have a merciless trainer strapped around your neck. For those slightly more averse to pain, you can watch [furrtek] and his friend [Dyak] suffer the consequences of poor gameplay for your amusement.

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Bench power supply resetting thingy

As is common among some hackers, [Henry] re-purposed an ATX power supply unit to function as a bench power supply for testing circuits on a breadboard (much like this fancy example).

However, safety mechanisms on some modern PC PSUs do not automatically reset after over-current protection has kicked in, which soon became annoying for [Henry]. In order to make his power supply more hacker-friendly, he wired up and programmed an ATtiny85V, using some Arduino libraries, to do that for him. This simple project is a great example of using a hack to improve a pre-existing hack.