[mike6789k] wanted to spice up his dorm room, so he built a cool music synchronized light show that struck us as being very well thought out. We have seen similar music-based visualizations before, but they tend to be pretty basic, relying on volume more than actual audio frequencies to trigger the lighting.

[mike6789k] didn’t want to build “just another” synchronized light show, and his all-analog approach gives a true representation of the music being played instead of just flashing lights along with the beat. Using a trio of simple filters, he broke the audio signals down into three distinct frequency bands before being driven through a high gain transistor to power a set of LEDs.

We were pretty impressed at how bright the display was given that he is using UV LEDs, but the 1W diodes seem to have no problem lighting up the place when aimed through the UV-reactive water, as you can see in the video below.

If you’re looking to make something similar for your next party, the folks over at Buildlounge were able to wrangle a schematic out of [mike6789k], which you can find here.

[David] has always wanted use UV LEDs to write on a phosphorescent surface ever since saw an article about it on Make. He accidentally purchased UV LEDs when he meant to buy purple ones, so he figured that his mistake was all the reason he needed to give UV light writing a try.

He built a PIC16F628 UV POV board using the LEDs, and while manually swiping the writer across various glow in the dark surfaces was cool, he wanted to keep the POV board stationary, moving the writing medium instead. He bought some phosphorescent vinyl, but found that it wasn’t too flexible, meaning he could not use a conveyor belt approach for his display. One day it dawned on him that a vinyl ring might work pretty well, and using a motor from an old cassette player, he constructed the UV writer you see above.

It seems to work pretty well despite a small flaw in the UV ring, and while [David] is happy with the results, he already has plenty of ideas in mind for the second revision.

Check out the video of his UV light ring in action after the jump.

[Thanks, Riley]

Some projects benefit greatly from the parts a builder is able to find. Take this UV exposure bed for photo-resist copper clad boards (translated). It looks like a commercial product, but was actually built by [TabascoEye] and his fellow hackers.

The main sources for parts were a flatbed scanner (which acts as the case) and two self-tanning lamps that use UVA flourescent bulbs. By sheer luck the bulbs and their reflectors are exactly the right size to fit into the top and bottom cavities of the scanner. The control hardware centers around an ATtiny2313 micorocontroller, which takes input from a clickable rotary encoder, and displays exposure information on a character LCD. The finished product deserves a place right next to other professional-looking exposure boxes that we’ve looked at.

A few years back [Bunnie] took a crack at cracking the security fuses on a PIC microcontroller. Like most of the common 8-bit microcontrollers kicking around these days, the 18F1320 that he’s working with has a set of security fuses which prevent read back of the flash memory and EEPROM inside. The only way to reset those security fuses is by erasing the entire chip, which also means the data you sought in the first place would be wiped out. That is, if you were limited to using orthodox methods.

[Bunnie] had a set of the chips professionally uncapped, removing the plastic case without damaging the silicon die inside. He set to work inspecting the goodies inside with an electron microscope and managed to hammer out a rudimentary map of the layout. Turns out that flash memory can be erased with ultraviolet light, just like old EPROM chips. Microchip thought of that and placed some shielding over the security fuses to prevent them being reset in this manner. But [Bunnie] managed to do so anyway, creating an electrical tape mask to protect the rest of the data stored in the chip while bouncing UV light underneath the shielding at an angle.

Want to uncap some chips of your own without enlisting the help of others? Give this method a try.

[via Dangerous Prototypes]

This water sculpture can stop drops of water in mid-air. This is accomplished by flashing LEDs to illuminate the droplets at just the right time. But it’s not limited to blinky lights alone. The top of the frame has eight nozzles, each fed by its own pump. An Arduino controls the pumps and the lights making it possible to create different motion effects by adjusting how events line up. For instance, the image above shows just two of the water nozzles on, but in the video after the break it appears one is dripping downward while the other is dripping upward.

Alas, there’s few build details for this but the source code is available for downloading. If we were going to build one of these ourselves we’d probably try to regulate the drips using some solenoids built from scratch. How would you do it? Leave your ideas in the comments.

[Jacques Lebrac] built a UV exposure box for printed circuit boards using just one LED. He usually makes boards that are just a few square inches and didn’t think building a box that had upwards of 80 LEDs was worth his time. He passed by the low power LEDs for a single 5W unit. Pumping 1.5A through this LED makes for some quick exposures, but causes heat issues. To solve this, an aluminum arm was used to mount the LED, acting as mechanical support and heat sink at the same time. The voltage regulator was glued directly to the chassis, providing at least some heat dissipation.

[Jacques] came up with an eloquent solution for holding the transparency and copper clad in place. A piece of acrylic is hinged on the back using a piece of aluminum tubing. The front has a magnet glued to it, with another one in the base to hold the cover tight to the work surface during operation.

There are two methods of using etchant resist when making circuit boards. We use the toner transfer method that requires ironing on laser toner to the copper, but you can also use chemical resist that reacts to ultraviolet light. [Bogdan] decided to start doing more of the latter so he built a UV exposure box to make the process easier.

It is possible to use flourescent light bulbs for this, but he decided to use UV LEDs, a method we’ve also seen before. But there’s always room to innovate, and [Bogdan] built-in a couple of nice features that are new to us. Because the UV light can be bad for your eyes, he included a set of red visible-light LEDs on the bottom half of the box that are used to align two layers of exposure mask when making double-sided boards. There’s also a switch that automatically shuts off the UV light when the box is opened. And as the coup-de-grace, he added a programmable timer to regulate the exposure, using his newly created box when etching the PCB for it.

[nmcclana] wrote out this very detailed instructible on building Mr. Burns, a sun burn alarm.  Enter your skin type, sunscreen type, and UV levels for the day and Mr. Burns will let you know when it is time to go seek shelter or re-apply that sunscreen. Built on a Propeller platform, he’s using a blue LED as the UV sensor. He mentions that the device is fairly accurate, however people tend to put sunscreen on too thin and that will throw off the readings. There is a video of it in action on the instructible.

This little art piece might be just the thing to add that mad scientist look to your room. It’s called the Coachella lamp and it makes use of several throwback display devices. At the top an Argon discharge lamp puts out ultraviolet light. Protruding from each of the four sides you can see a set of decatrons. There’s also four Nixie tube bar graphs standing tall from each corner of the base. The final touch is the colored glow in the center which is provided by LEDs. We’ve embedded some video of the device after the break.

The lamp is powered by a wall outlet and controlled with an Arduino. We’ve seen deactrons used as timing devices and would love to see some clock functionality added to the lamp. Trying to decipher the time from the different Nixie displays would put this up there with some of those other hard to read timepieces.

[Thanks Brian]

Tired of those awful sunburns? [Nikko Knappe's] UV sensing glasses will warn you before you become crisp and red as a lobster. The bump added to the bridge support hides a TSL230R light frequency sensor. The device automatically switches on when the arms are unfolded and starts tracking cumulative exposure. If it detects a rising UV level, or you are about to burn based on skin type, an LED inside one arm of the frames will flash to inform you.

This has some potential if you think David Brin’s Earth outlines how climate change is really going to play out. Either way it’s still fun and we give bonus points to [Nikko] for disguising the lilypad that controls this as a flowery hair-pin.

[Jeremy] had some chips on hand that included EPROM.  We’re not talking about EEPROM, we mean EPROM that need a UV light source to erase. Most people don’t want to drop a few hundred dollars on a dedicated EPROM eraser, there must be another way.

Boy, EPROM really suck. But so do pacifiers and he already had a solution for exposing those to UV. He pulled out his $30 UV pacifier cleaner and tossed the chip inside. Two times through the cleaning cycle and the data was gone. We’ve looked into using UV LEDs to do the job but some experimentation shows that it doesn’t work. These pacifier cleaners are cheap and easy to get a hold of. The real question is are you still using chips that require UV for erasing?

[Kizo] repurposed a flatbed scanner to use as an exposure box for making printed circuit boards. Exposure time is controlled by an AVR ATtiny2313 microcontroller. The device is connected to a separate display board to control four 7-segment displays using one shift register for each. Time is set in ten second increments and once started, switches on the lights with a relay. Once the right exposure time has been reached, the lights are switched off and a piezo speaker is buzzed. There’s no mention of they type of bulbs he’s using but they look like compact fluorescent with tin foil beneath as a reflector.

If these are just CFL bulbs, how will the performance compare to a light box based around a UV light source?

[Thanks Jake]

Ok, there aren’t any usefull applications we can think of for this one, but we want one really badly. This is a combination of a miniPOV, some UV LEDs, a CNC rig, and some glow in the dark paper. The Ghost matrix works similar to a dot matrix printer where it flashes the UV light to activate the paper. The final effect is very nice. Great job on this one.

[via Laughing Squid]

[Barrett] sent in this hack he did to an airsoft pistol. He was using “tracer rounds” or glowing airsoft pellets and found that there was no commercially available way of charging them up with uv light before they are shot. He cracked open his pistol, removed the safety mechanism, and placed a UV led in it’s place. Now, when he turns it on, it charges up the pellets so they’re nice and bright. If he’s playing airsoft at night, won’t that bright purple light give away his position? yeah, we know he was probably just using that pistol to show the mod off.

AU Optronics Corp has unveiled a new LCD panel that doubles as a fingerprint scanner. Each pixel is equipped with 4 optical sensors, so a 320×240 screen would have a scanning resolution of 640×480. They have also experimented with different sensors, such as UV. You can see an LCD panel that detects and displays the UV index above. Why did they use a secondary display to show the data though?

[via Gearlog]