Some people aren’t too crazy about the rush of RFID enabled credit & debit cards, and the problem is, you don’t really have a choice what card you get if the bank sends you a new one! Well if you really don’t like this on your card for whatever reason, it’s pretty easy to disable.
[James Williamson] recently got a new debit card with RFID technology — the problem is it was messing with his access card at work, the readers would beep twice, and sometimes not work. He decided to disable it because of this and that he didn’t really use the tap to pay feature, nor was he completely convinced it was as secure as the bank said.
Since these RFID chips use antennas made of copper wire, he could have just started slicing his card with a knife to break the antenna — but, since he has access to a CT scanner, he thought he’d scan it to figure out where everything was.
Simply make a small notch in the edge of your card, or snip off one of the corners. This breaks the antenna and prevents power to the chip when held near a reader — though if you don’t have access to a CT scanner you might want to double-check next time you buy something!
Now there is another side to this — maybe you actually like the whole tap to pay thing, well, if you wanted to you could get a supplemental card, dissolve it in acetone, and then install the RFID chip into a finger ring for Jedi-like purchasing powers!
Jacob’s Ladders are a staple experiment in any self-respecting mad scientist’s lair — err, a hacker’s workshop. And why not? High voltage, arcing electricity, likely more than enough to kill you even — brilliant! But in all their awesomeness, Jacob’s ladders really aren’t that complex.
In [Kevin Darrah’s] latest tutorial he shows us how to make one out of a transformer taken from an oil furnace. Why exactly does an oil furnace even have a high voltage transformer in the first place? They’re actually used as the ignition source, like a pilot light!
The one [Kevin] has is a 110VAC to 10,000VAC transformer, which puts out about 20mA (probably enough to kill you). And to turn it into a Jacob’s Ladder, you’ll just need a two long stiff wires (copper is a good candidate). The wires are closest at the bottom where the transformer can easily arc — this arc then ionizes and heats the air causing it to rise, carrying the arc with it. As the arc continues up the ladder it gets longer and longer as the wires become farther apart, becoming more and more unstable until it breaks. When this happens the arc forms again at the lowest point of resistance — the bottom.
My introduction to electronic manufacturing was as a production technician at Pennsylvania Scale Company in Leola PA in the early 1980’s. I learned that to work on what I wanted to work on I had to get my assigned duties done by noon or thereabouts. The most important lesson I had learned as a TV repairman, other than not to chew on the high voltage cable, was to use your eyes first. I would take a box of bad PCB’s that were essentially 6502 based computers that could count and weigh, and first go through inspecting them; usually the contents were reduced 50% right off by doing this. Then it was a race to identify and fix the remaining units and to keep my pace up I had to do my own desoldering.
It worked like this; you could set units aside with instructions and the production people would at some point go through changing components etc. for you or you could desolder yourself. I was pretty good at hand de-soldering 28 and 40 pin chips using a venerable Soldapulit manual solder sucker (as they were known). But to really cook I would wait for a moment when the production de-soldering machine was available. There was one simple rule for using the desoldering station: clean it when done! Failure to do so would result in your access to the station being suspended and then you might also incur the “wrath of production” which was not limited to your lunch bag being found frozen solid or your chair soaked in defluxing chemicals.
If you’re fortunate enough to have a garage and a workshop, you probably also have neighbors. The truly blessed must work within the confines of an HOA that restricts noise, porch couches, and most types of fun. [Mike] is among the truly blessed, and when he decided to design a cabinet for his CNC equipment, he took noise dampening into consideration.
[Mike]’s design isn’t a blanket noise dampener; it’s specifically designed for the high-pitch symphony of his router, compressor, and vacuum. He also sought to avoid vibrating the cabinet. To achieve this, the sound-dampening panels are hung on eye hooks with a 1/2″ gap between them and the frame. The backer boards are cut from 3/4″ plywood. [Mike] considered using cement board, but thought it might be overkill since he plants to shell the cabinet in a layer of 3/4″ plywood.
The deadening material is paper pulp made from various shredded papers. After soaking the shreds in water and blending the mixture to an oatmeal consistency, he drained most of the water through a cloth bag. Then he added just enough wood glue to hold the pulpy goo together. The tropical punch Kool-Aid powder isn’t just for looks; it provides visual confirmation of even glue distribution.
[Mike] made some tape walls around the edge of his backer boards to hold the mixture in place and painted on some wood glue to hold the pulp. He spread the tropical concoction to 1/2″ thickness with a tiling trowel to avoid compressing it. The peaks and valleys help scatter any sound that isn’t absorbed. Pudding awaits you after the jump.
[Steven Dufresne] of Rimstar.org is at it again with another very functional science experiment. This week he’s showing us how he made a large electrostatic motor, also known as a Corona Motor.
A Corona motor makes use of a cool
phenomenon called the Corona discharge, which is the ionization of a fluid
(in this case, air) surrounding a conductor that is energized. He’s done other high voltage experiments that take advantage of this, like his Ion Wind propelled Star Trek Enterprise!
The motor works by using an even number of electrodes on the motor, each electrically charged; positive, negative, positive, negative, etc.
Because each electrode is the opposite charge, they want to repel each other — but since the cylinder is electrically insulated, the charges have no where to go — instead the cylinder begins to rotate as the charges attract back and forth — when a positive charge on the insulation meets a negatively charged electrode, the charge is removed by ionization (creating the corona effect), and the cycle continues. The direction of rotation is determined by the angle of the electrodes. The motor can get going pretty fast but doesn’t have that much torque or power.
Conductive ink or paint is lots of fun. It opens up tons of possibilities for flexible and unique circuits — unfortunately, it’s pretty expensive. [Brian McEvoy] shows us how to make your own for cheap, and it works great!
He started trying to formulate his own recipe after playing with other Instructable guides and commercially available paint, and what he found is it’s really not that complex! Graphite powder, acrylic paint, and a jar with an airtight seal — seriously, it’s that simple! But, like any engineer worth their salt (he calls himself the 24 Hour Engineer), he had to do some tests to compare his formula.
In a detailed experiment he compares his formula to the commercially available Wire Glue, and two other recipes using Elmer’s Glue-All and graphite, and Titebond III with graphite. The results? Acrylic paint and graphite produce the most conductive material — and the cheapest!
For projects requiring a bit more juice, the mass production of those small rectangular lithium ion batteries for cell phones, cameras and other electronics are extremely useful — the problem is, how do you mount them, short of soldering the terminals in place? With a bit of perfboard of course!
[Jason] came up with this idea when he was trying to figure out a way to mount small lithium cells for a battery fuel gauge for another one of his projects. He found if you use good quality perfboard you can use a 90 degree male pin header to contact the terminals, and a strip of female pin header as a kind of battery stop at the other end. This allows you to very snugly squeeze the battery in place — you may need to adjust the length of the male pins though in order to fine tune the fit!
Now you can add a nice wire terminal, solder up the connections, and there you have it, an easy to make, extremely useful battery holder!