Salvaging Gold From Old Electronics


If you’re hoarding old electronics like us, there’s a good probability you have a decent amount of gold sitting around in cardboard boxes and storage containers. Everything from old PCI cards, IC pins, and even printers have a non-negligible amount of precious metals in them, but how do you actually process those parts and recover that gold? [Josehf] has a great tutorial for gold recovery up on Instructables for the process that netted him an ounce of gold for three months’ work.

After cutting up a few circuit boards to remove the precious gold-bearing parts, [Josehf] threw these parts into a mixture of muriatic acid and hydrogen peroxide. After a week, the acid darkened and the gold slowly flaked off into dust. This gold dust was separated from the acid by passing it through a coffee filter and readied for melting into a single nugget.

Gold melts at 1064 ˚C, much hotter than what can be obtained by a simple propane torch. This melting point can be reduced by the addition of borax, allowing the simplest tools – a propane torch and a terra cotta crucible – to produce a small gold nugget.

For three months of collecting, stripping, and dissolving electronic parts, [Josehf] netted 576.5 grains of gold, or at current prices, about $1500 worth of the best conductor available. Not too bad, but not something we’d use as a retirement plan.

Thanks [Matthias] for sending this in.

Heirloom Chemistry Set

heirloom chemistry  set

We try not to share too many crowd funding projects, but when a tipster sent us to this Heirloom Chemistry Set we knew some would-be chemistry hackers might just want to see it!

[John Farrell Kuhns] runs a small science store with his wife in Kansas City called the H.M.S. Beagle, where young scientists (and adults!) can buy professional lab supplies, equipment, and the resources to study all things from chemistry to physics!

It all started when [John] was a child in the 1950′s and he received the classic Gilbert Chemistry Set as a Christmas present, which help set him on the course of becoming a professional research chemist. Now, wanting to share his love of chemistry with his children, he realized there just isn’t the same kind of chemistry sets available commercially!

Since the opening of his store he has made many custom chemistry sets very similar to the originals, but these were almost all one-off’s and very time consuming to make. So recently he decided to try making a set that he can produce in fair numbers to meet the demand, and so he started this Kickstarter to help it get off the ground. It’s already surpassed its goal by two times!

We wish we had one when we were growing up!

[Thanks Jeremy!]

Copper Electroplating the Cheap and Safe Way

copper plating

[A_Steingrube] has posted a guide to his favorite method of copper electroplating. Plating copper onto other metals is popular with the steampunk crowd, but it does have other uses. Copper plate is often used as a prep step for plating other metals, such as nickel and silver. It also (usually) increases the conductivity of the metal to be plated. [A_Steingrube] is using the copper acetate method of plating. What is somewhat novel about his method is that he chose to make his own electrolyte solution from household chemicals. The copper acetate is created by mixing distilled vinegar and household hydrogen peroxide in a 50/50 ratio. The mixture is heated and then a piece of copper scouring pad is placed in. The scouring pad is partially dissolved, providing copper ions, and turning the solution blue.

The next step is to clean the material to be plated. [A_Steingrube] uses Cameo Aluminum and Stainless cleaner for this, though we think any good degreaser will work. The actual electroplating process consists of connecting a piece of copper to the positive terminal of a 6 volt battery. Copper scouring pad is again used for its high surface area. The material to be plated is connected to the negative side of the battery. He warns to keep the solution and the material being plated in constant motion to avoid heavy “burn spots”, which can flake off after the plating process. The results speak for themselves. As with any bare copper material, the electroplated layer will quickly oxidize if not protected.

Electrochemical Etching With a Microcontroller


While most of the time the name of the game is to remove a lot of metal, etching is an entirely other process. If you just want to put a logo on a piece of steel, or etch some labels in a piece of aluminum, You need to think small. Mills and CNC routers will do, but they’re expensive and certainly not as easy to work with as a small, homebrew electrochemical etcher.

This etchinator is the brainchild of [Gelandangan], and gives the techniques of expensive commercial etchers to anyone who can put together a simple circuit. This etcher can etch with both AC and DC thanks to a H bridge circuit, and can be fabbed up by anyone who can make their own circuit board.

To actually etch a design in a piece of metal, simply place the piece on a metal plate, put the stencil down, and hold a felt-covered electrode moistened with electrolyte down over the stencil. Press a button, and in about 30 seconds, you have a wonderfully etched piece of metal.

[Gelandagan] has some templates that will allow you to make your own electro etcher, provided you can etch your own boards and can program the PIC16F1828 microcontroller. All this info is over on the Australian blade forum post he put up, along with a demo video below.

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Towards a Low Cost, Desktop CT Scanner


For [Peter Jansen], the most interesting course in grad school was Advanced Brain Imaging; each class was a lecture followed by a trip to the imaging lab where grad students would take turns being holed up in a MRI machine. A few years into his doctorate, [Peter] found himself in a very opportune situation – his local hackerspace just acquired a shiny new laser cutter, he had some free time on his hands, and the dream of creating a medical imaging device was still in the back of his mind. A few weeks later, the beginnings of an open source CT scanner began to take shape.

This isn’t an MRI machine that [Peter] so fondly remembered from grad school. A good thing, that, as superconducting magnets chilled with liquid helium is a little excessive for a desktop unit. Instead, [Peter] is building a CT scanner, a device that takes multiple x-ray ‘slices’ around an axis of rotation. These slices can then be recompiled into a 3D visualization of the inside of any object.

The mechanics of the build are a Stargate-like torus with stepper motor moving back and forth inside the disk. This, combined with the rotation of the disk and moving the bed back and forth allow the imager to position itself anywhere along an object.

For the radioactive detector, [Peter] is using a CCD marketed as a high-energy particle detector by Radiation Watch. Not only does this allow for an easy interface with a microcontroller, it’s also much smaller than big, heavy photomultiplier tubes found in old CT scanners. As for the source, [Peter] is going for very low intensity sources, most likely Barium or Cadmium that will take many minutes to capture a single slice.

The machine operates just above normal background radiation, so while being extremely safe for a desktop CT scanner, it is, however, very slow. This doesn’t bother [Peter], as ‘free’ time on a CT scanner allows for some very interesting, not seen before visualizations, such as a plant growing from a seed, spreading its roots, and breaking the surface as a seedling.

[Peter] still has some work to do on his desktop CT scanner, but once the stepper motor and sensor board are complete, he should be well on his way towards scanning carrots, apples, and just about everything else around his house.

[Ben Krasnow] Discusses the Heat Treatment of Steel


For home metallurgy, there are two sources of information for the heat treatment and tempering of steel. The first source is academic publications that include theoretical information, while the second includes the home-spun wisdom of blacksmiths who learn through trial and error. [Ben Krasnow] put up a great video that tries to bridge that gap with some great background information with empirical observations to back up his claims.

For investigating the hardness of steel, a few definitions are in order. The first is stiffness, or the ability of a material to ‘spring back’ after being flexed. The second is strength, specifically yield strength, which is the amount of strain a material can withstand before being permanently deformed.

[Ben] did all these experiments with a 1/8″ W1 steel drill rod. As it came from McMaster, this rod could handle a bit of force before becoming permanently bent, and in terms of stiffness was much better than a piece of coat hanger wire [Ben] had lying around. After taking a piece of this drill rod, heating it up to a cherry red and quenching it in water, [Ben] successfully heat treated this steel to a full hardness. After putting it on his testing jig, this full hardness steel didn’t deform at all, it simply broke.

Full hardness steel is basically useless as a structural material, so [Ben] tried his hand at tempering pieces of his drill rod. By putting a few pieces in a kiln at the requisite temperature, [Ben] was able to temper his drill rods to be stronger than the stock material, but not as terribly brittle as a full hard rod.

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DIY soda can battery


It may not be particularly useful to create some makeshift batteries out of soda and soda cans, but it’s a good introduction to electrodes and electrolytes as well as a welcomed break from lemons and potatoes. The gang at [Go-Repairs] lopped off the can’s lid and temporarily set the soda aside, then took steel wool to the interior of the can to remove the protective plastic coating. The process can be accelerated by grabbing your drill and cramming the steel wool onto the end of a spade bit, although pressing too hard might rip through the can.

With the soda poured back in, you can eek out some voltage by clipping one lead to the can and another to a copper coin that’s dunked into the soda. Stringing along additional cans in series can scale up the juice, but you’ll need a whole six pack before you can get an LED working—and only just. The instructions suggest swapping out the soda for a different electrolyte: drain cleaner, which can pump out an impressive 12 volts from a six pack series. You’ll want to be careful, however, as it’s likely to eat through the can and is one lid away from being dangerous.

Stick around for a quick video after the break, and if you prefer the Instructables format, the [Go-Repairs] folks have kindly reproduced the instructions there.

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