Make Your Own Magnetic Ink

July 17, 2012 by Mike Szczys 12 Comments

Here [Catarina Mota] is showing off a ring of magnetic ink printed on a piece of paper. It’s strong enough to hold a disc magnet in place when the paper is raised vertically. This strength comes from mixing your own batch of ink.

Magnetic ink has been around a long time and is most often used in banking. The account number and routing number on the bottom left of paper checks are printed in magnetic ink to allow for automated recognition. Iron oxide is charged by the reader as it passes through. In this case, magnetite is used as the doping agent as it has very strong ferromagnetic properties. By mixing it with acrylic medium in a vortex mixer you end up with a homogeneous ink.

There’s a quick demo after the break that shows how well this printed ring holds the magnet. What are some things for which you would use this ink? Leave a comment to let us know.

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I Got 99 Volts And My Anodizing’s Done!

July 13, 2012 by Mike Nathan 12 Comments

anodizing-titanium-with-coke

[POTUS31] had a need for anodized titanium, but the tried and true “submersion” method was not going to work out well for what he was trying to do. In order to create the look he wanted he had to get creative with some tape, a laser cutter, Coke, and a whole lot of 9v batteries.

His Ring-A-Day project has him creating customized rings based on reader feedback, and lately the requests have had him searching for a good way to color metal. Anodizing titanium was a sure bet, though creating detailed coloring on a small medium is not an easy task.

[POTUS31] figured that he could gradually anodize different areas of the ring by using laser-cut tape masks, allowing him to selectively oxidize different portions of his creations as he went along. Using the phosphoric acid prevalent in Coke as his oxidizing agent along with a constantly growing daisy-chain of 9-volt batteries, he had a firm grasp on the technique in no time. As you can see in the picture above, the anodizing works quite well, producing vivid colors on the titanium bands without the need for any sort of dye.

[POTUS31’s] favorite color thus far? A rich green that comes from oxidizing the metal at you guessed it – 99 volts.

[via Make]

Make Your Own Integrated Circuits At Home

July 9, 2012 by Brian Benchoff 25 Comments

The Nyan Cat you see above is only 600 micrometers from head to tail. To put that into perspective, that’s about 10 times the diameter of a human hair. Also, that Nyan is etched into 200 nanometer thick copper foil and is the work of the HomeCMOS team, who is developing a hobbyist-friendly process to make integrated circuits and MEMS devices at home.

The project is far from complete; HomeCMOS has yet to produce a working IC but a few experiments – getting wet etching down pat and even building an almost working quantum qbit – are remarkable given the small amount of equipment and tools involved.

The HomeCMOS team has yet to actually make an integrated circuit or MEMS device, [Jeri Ellsworth] has shown this is possible by making transistors and integrated circuits at home. While there won’t be chips with millions of transistors coming out of the HomeCMOS lab anytime soon, it’s more than possible to see a few small-scale integration-level tech such as a few logic gates or a regulator.

More DIY Solder Flux

June 20, 2012 by Mike Szczys 17 Comments

[GuShH] wrote a guide for making your own rosin-based solder flux. According to [Stephen] — who sent in the tip and tried this method himself — is works well, it’s cheap, but you will need to clean up a bit after using it on a PCB.

Only two ingredients are necessary to make your own liquid or paste flux: rosin and a solvent. The rosin being weighed in the image above, can be found from several sources. We looked in on the same method quite recently where flux was sourced from a music store. But [GuShH] suggests that if you can find some from a hardware store it is better because the music store variety tends to be ‘molten’ and doesn’t work quite as well.

Proportions are listed on his guide for light, medium, and heavy concoctions. He recommends isopropyl alcohol as the solvent, and has stored the flux in a clear dropper bottle. We’re fans of needle bottles and asked about sourcing them in a previous post (linked in the paragraph above) so check that comments section if you don’t know where to get one.

Homemade Silicon Carbide LED

June 5, 2012 by Mike Szczys 18 Comments

Here’s an LED indicator which was made at home out of a Silicon Carbide (SiC) crystal (Internet Archive Mirror). The concept is simple, but a bit of trial and error goes into getting that tiny amber spot to light up.

The guesswork comes in finding the right piece of crystal. First [KOS] broke it into tiny pieces, then he started poking the chunks with electrified probes to see if he could get some light out of them. Once an active area was found he needed a base for the crystal. The image above shows the two nails which he used. This provides a large mounting area that also acts as a heat sink to make sure the LED won’t burn itself out. There’s a solder blob which he kept molten with his iron until the crystal could be pushed into place. That holds it securely as the pin which serves as the cathode is positioned.

The whole setup is soldered to some protoboard and is ready to use. This is the second time we remember seeing this technique used to fabricate LEDS. The first time was an accident.

How Anodization Is Used To Make Pretty IPod Colors

May 29, 2012 by Mike Szczys 26 Comments

What do those colorful iPod Nano cases have in common with sapphires? In both substances the color is not on the surface, but integrated in the structure of the material. As usually, [Bill Hammack] unveils the interesting concepts behind coloring metal through anodization in his latest Engineer Guy episode.

We’re not strangers to the anodization process. In fact we’ve seen it used at home to change the color of titanium camping utensils. [Bill] explains what is actually going on with the electrochemical process; touching on facts we already knew; like that the voltage range will affect the color of the annodized surface. But he goes on to explain why these surfaces are different colors and then outlines how anodized metals can be dyed. That’s right, those iPod cases are colored with dye that will not wash or scratch off.

Pores are opened when the aluminum goes through anodization. Those pores are filled with dye, then the metal is boiled in water which closes them, sealing in the color. Pretty neat!

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Conductive Ink Circuit Experiments

May 18, 2012 by Mike Szczys 12 Comments

This glowing LED is proof that the experiments [Nvermeer] is doing with conductive ink are working. We’re filing this one as a chemistry hack because you need to hit the lab ahead of time in order to get the conductivity necessary for success. He reports that this technique uses a copper powder suspended in an epoxy intended for spray painting. Before mixing the two he etched the powder in ammonium persulfate, then washed it in deionized water which made it a much better conductor.

We gather that the ink was applied with the brush seen in the photo. But since this uses that spray paint friendly solution to host the copper powder we wonder about stenciling with something like masking tape in order to spray the circuit paths onto the substrate.

There’s not too much info up yet, but [Nvermeer] does link to one of our other favorite conductive ink projects.