Simulating CRT or Vector displays for more realistic emulation

simulated-crt-monitor-for-emulatorsScaled down it’s not as obvious that this image isn’t a crystal clear rendering of Mortal Kombat gameplay. But we’ve linked it to the full size version (just click on the image) so that you can get a better look. Notice the scan lines? This is the result of an effort to more accurately mimic the original hardware displays used in classic games. [Jason Scott] takes a look at the initiative by describing what he thinks is missing with the picture perfect quality of modern emulators.

One such effort is being mounted for MAME (Multiple Arcade Machine Emulator). There is a series of filters available — each with their own collection of settings — that will make your modern LCD display look like it’s a run-of-the-mill CRT. This is a novelty if you’re a casual gamer who dusts off the coin-op favorites twice a year. But if you’re building a standalone game cabinet this may be a suitable alternative to sourcing a working display that’s already decades old.

Collection of Nixie bar graphs bump to the beat

This VU meter uses Nixie tubes as the display. There are a total of fourteen IN-13 bar graph tubes that map out the audio spectrum. The build uses purely hardware for the display; no microcontroller processing, or dedicated VU-meter chips were used.

Input begins with a dual Op-Amp along with a pair of potentiometers which allow the left and right channels to be balanced. Both channels are then each split into seven signals, which explains the layout of tubes seen above. Each signal is then fed through a voltage divider to envelope the output between 0V and 6V. There is also a low-pass filter to handle sudden volume spikes which don’t work well with the nixies. But as shown in the video after the break, all that work has paid off. Thr clip gives us a look at the green protoboards which host all of this filtering hardware. You’ll want to turn the volume down for the first couple of demonstrations which use a sweep to test the system.

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AVR chiptune project turns this simple code into music

[Mark] had seen a few examples of algorithmic music generation that takes some simple code and produces complex-sounding results. Apparently it’s possible to pipe the output of code like this directly to audio devices on a Linux box, but [Mark] decided to go a different direction. His project lets you play simple algorithms as audio using AVR microcontrollers.

Now the code work for this is very simple, but he hardware implementation is where things get interesting. Ostensibly, [Mark] didn’t have the components available to build a filter to use PWM as an audio signal. Being that he’s a ham operator, he grabbed some radio equipment he had on hand and whipped up an alternative. He’s feeding the PWM from an Arduino into the voltage controlled oscillator on a board meant for high-altitude balloon telemetry. The signal broadcast by this board is then picked up by his radio receiver, and played on some speakers.

Rube-Goldberg contraptions aside, the effect is pretty interesting, as you can hear in the latter half of the video clip which we’ve embedded after the jump.

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Making your own lab instruments

[Andrey Mikhalchuk] is trying to gather a base set of lab instruments. Specifically, he’s looking for hardware that will let him quickly filter solids out of a liquid. He first started by adding a cotton disk to a plastic funnel. It does the job, but when left to gravity it’s quite slow. He needed a way to speed up the flow even when the filter is heavily clogged with particulates.

There’s already a solution to this problem. It’s a glass container called a Büchner Flask. These feature a glass tube coming out from the neck. By hooking a vacuum pump up to this tube, reduced pressure inside the flask will pull the liquid through the filter in no time. Rather than purchase the specialty item, [Andrey] altered a rubber stopper to accept both the funnel, and a glass tube. This is a cheaper version because it uses a common conical flask but it works just as well. To create the vacuum, an altered bike pump was used. Check out videos of both hacks after the break. Continue reading “Making your own lab instruments”

chipKIT Sketch: Mini Polyphonic Sampling Synth

In our hands-on review of the Digilent chipKIT Uno32, we posed the question of what the lasting appeal might be for a 32-bit Arduino work-alike. We felt it needed some novel applications exploiting its special features…not just the same old Arduino sketches with MOAR BITS. After the fractal demo, we’ve hit upon something unique and fun…

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Junkyard fish tank

So your house looks like a dumping ground for useless junk? Yeah, we know it’s the hacker’s curse… you just can’t stop salvaging stuff. But follow [Pontazy69’s] lead by building something useful out of that junk. He took an old polystyrene box and made it into this fishtank. You can see that the sides and back of the box has gone unaltered, but the front wall is missing. [Pontazy69] marked and cut straight lines while leaving a lip around the edge. Silicone was used to glue some acrylic (or perhaps glass?) to the inside of this lip. Once dried he added another bead around the outside to ensure it doesn’t leak. Few fish would be happy here without some type of filter so he built one of those out of an old plastic bottle and some other pieces. See videos that show you how to build both the tank and the filter after the break.

We love aquarium hacks almost as much as clock hacks. So check out the water exchange system, and a couple of different lighting systems. Then document your own aquarium projects and let us know about them.

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Turning music into a light show

[nickinoki] Made a light show using some amplifiers and an arduino. First he created a microphone circuit based around a LM386 Audio Amplifier. After amplifying the output of the microphone a second time, he uses three bandpass filters to block all but a few desired frequencies from reaching the arduino.  By only letting a few frequencies through the arduino is able to determine if the song is louder at higher or lower frequencies.  Then using the three analogue inputs he created a scheme for generating the light show on an arduino. While he was unable to achieve the exact target frequencies with his bandpass filters they worked well enough to allow him to successfully generate the light show.