[CNLohr] Demos His Photoetch PCB Process


If you’re going to learn something, it only makes sense to learn from a master. [CNLohr] is known around these parts for his fablous PCBs, and he’s finally started to document his entire fabrication process.

[CNLohr] is using a photoetch process, where a mask is created with a laser printer on overhead transparencies. He covers the copper clad boards with a Riston photosensitive mask—available here, and they accept Bitcoin—sent through a laminator, and exposed with the laser printed mask and a UV grow bulb. After the mask has developed, [CNLohr] drops his boards into a ferric chloride bath that eats away the unexposed copper. He then removes the photomask with acetone and cuts the boards with a pair of aircraft snips, and they’re ready to be soldered up with components.

Yes, home PCB etching tutorials are pretty much a solved problem, but [CNLohr]’s work speaks for itself. He’s also the guy who made a microcontroller/Linux/Minecraft thing on a glass microscope slide. Learning from a guy with these skills means you’re learning from one of the best.

Video below, and there’s also a video going over the design of a PCB using KiCAD (!) and TopoR (!!!) available here.

Continue reading “[CNLohr] Demos His Photoetch PCB Process”

Hard drive centrifuge for sensitizing copper clad boards


We would wager that most of the home etched PCB projects we see around here use the toner transfer method. But the next most popular technique is to use photosensitive ink which resists the etching acid once it has been exposed to light. Most people buy what are called pre-sensitized boards, but you can also get ink to make your own. [Jardirx] does this, and uses an old hard drive to apply an even layer of the light-sensitive ink.

The narration and subtitles of the video found after the break are both in Portuguese, but it’s not hard to figure out what’s going on here. He begins by using double-sided foam tape to secure the piece of copper clad board to the hard drive platters. You’ll want to center it as best as you can to keep the vibrations to a minimum. From there [Jardirx] applies a coating of the ink using a brush. The image above is what results. So as not to get ink everywhere, he then lowers a soda bottle with the bottom cut off to catch the excess. Power up the drive for a few seconds and the board will have a nice even layer ready for a trip through a UV exposure box.

Continue reading “Hard drive centrifuge for sensitizing copper clad boards”

Laser charged glowing display

Here’s one of the best takes on a glowing display that we’ve ever seen. Currently [H] is using his creation as a fuzzy clock, but it is certainly capable of displaying just about any messages.

The project uses a wheel of luminous paper as the display surface. This has a glow-in-the-dark quality to it which can be charged up using a bright light source. In this case a UV laser diode was used. This is perhaps the best possible source as its intensity will allow for very quick charging. The innovation here is the use of a second disk as a stencil. Look closely in the image above and you will see that the laser diode is mounted perpendicular to the display surface itself. A mirror reflects — and we believe slightly spreads — the laser dot. It then passes through a cut-out on the black wheel which is shaped as the desired character. As you can see in the video after the break, this results in a crisp and clear glowing letter.

Compare this project to the one that moves the diode itself like a plotter and we think you’ll agree this is a simpler implementation which still looks great!

Continue reading “Laser charged glowing display”

Ikea provides a great UV exposure box

Making your own boards at home is among the heights of achievement for home tinkerers, and one fraught with frustration. The toner transfer process requires carefully peeling away layers of photo paper, and milling your own circuit boards is an exercise in complexity. One of the best options is using photosensitive copper boards, but this requires exposing the masked-off copper to fairly intense UV light. A UV exposure box is a wonderful project, then, and something [Carlo] just about has wrapped up.

The first portion of [Carlo]’s build involved placing 135 UV LEDs on a piece of protoboard. This UV source eats up a surprising amount of power; [Carlo] is using 12V for the supply, so an old industrial power supply is more than capable of dishing out the 1.5 Amps required for the build.

Next, [Carlo] needed a timer for his exposure box. He settled on a design based on an ATMega8 turning a high voltage transistor on and off with a character LCD for the user interface. A few buttons allow [Carlo] to set the countdown timer, after which the LEDs turn on for a set period of time.

All this was packaged into a small box [Carlo] picked up from Ikea. It’s a very useful build, and judging from the video after the break, extremely easy to use.

Continue reading “Ikea provides a great UV exposure box”

Taking a dump from some old hardware

NYC Resistor shows you how to have some fun with electronics from the junk bin. Their post called The Joy of Dumping encourages you to look around for older memory chips and see what they’ve been hiding away for all these years.

The targets of their hunt are EPROM chips. Note the single ‘E’. These are Erasable Programmable Read-Only Memory chips, and predate EEPROM which adds “Electrically” to the beginning of the acronym.  You used to use a UV light source to erase the older types of memory. In fact we’ve seen some EPROM erasers as projects from time to time. These shouldn’t be too hard to find as they were prevalent as cheap storage back in the 1980’s.

If the quartz window on the top of the chips has been shielded from ambient UV light, you should still be able to read them and it’s as easy as hooking up your Arduino. Is it useful? Not really, but it still can be neat to interface with what might otherwise never make its way back out of the junk box.

A flashlight for any occasion

Whether you’re trying to light your path, build your own night vision, or do some tanning at home, this flashlight has you covered. [David Prutchi] designed the high power flashlight with three swappable heads.

He built the base unit out of aluminum pipe. It’s got plenty of room for the four 9V batteries that act as the power source. The driver circuit is just a bit smaller than one of those batteries, and to bring the whole thing together [David] and his helper added a potentiometer, toggle switch, and quick connector which makes head swaps a breeze. The heads themselves are all LED based, with one for visible light, another for infrared, and the final module outputs ultraviolet. We joke about tanning with it, but at 10 Watts you should be more worried about accidental damage to your vision.

The finished product is shown checking the security ink on some Canadian Currency. This would also make a nice secondary light source for your night vision monocle.

Slick music synchronized light show uses UV LEDs and water


[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.

Continue reading “Slick music synchronized light show uses UV LEDs and water”