Demonstrating Science at Harvard University

What if there was a job where you built, serviced, and prepared science demonstrations? This means showing off everything from principles of physics, to electronic theory, to chemistry and biology. Would you grab onto that job with both hands and never let go? That was my reaction when I met [Dan Rosenberg] who is a Science Lecture Demonstrator at Harvard University. He gave me a tour of the Science Center, as well as a behind the scenes look at some of the apparatus he works with and has built.

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Growing Copper and Silver Crystals for Art

Usually when Hackaday covers electroplating techniques, it’s to talk about through-hole PCB plating. But did you know you can use the same method to produce beautiful copper and silver crystal structures?

[Fred and Connie Libby] are kind enough to share how they make their crystals that they sell in tiny glass vials you can wear around your neck. The process is simple as you would think; it’s just an electrolyte solution, with a current passing through it, depositing the metal in an ion-exchange. Rather then stop once the part is sufficiently covered, you let the process run amok, and soon large crystal formations begin to emerge. [Fred and Connie] share their technique very briefly, so if you’re looking for a more detailed how-to guide, you can find one here.

Although silver crystals are a bit out of our budget, we wonder how large of a copper crystal could be grown? Large enough to be displayed on a coffee table? Surely such a work of art and science could be an interesting conservation piece in any hacker’s home.

Home Brew Supercapacitor Whipped Up In The Kitchen

[Taavi] has a problem – a wonky alarm clock is causing him to repeatedly miss his chemistry class. His solution? Outfit his clock radio with a supercapacitor, of course! But not just any supercapacitor – a home-brew 400 Farad supercap in a Tic Tac container (YouTube video in Estonian with English subtitles.)

[Taavi] turns out to be quite a resourceful lad with his build. A bit of hardware cloth and some stainless steel from a scouring pad form a support for the porous carbon electrode, made by mixing crushed activated charcoal with epoxy and squeezing them in a field-expedient press. We’ll bet his roommates weren’t too keen with the way he harvested materials for the press from the kitchen table, nor were they likely thrilled with what he did to the coffee grinder, but science isn’t about the “why?”; it’s about the “why not?” Electrodes are sandwiched with a dielectric made from polypropylene shade cloth, squeezed into a Tic Tac container, and filled with drain cleaner for the electrolyte. A quick bit of charging circuitry, and [Taavi] doesn’t have to sweat that tardy slip anymore.

The video is part of a series of 111 chemistry lessons developed by the chemistry faculty of the University of Tartu in Estonia. The list of experiments is impressive, and a lot of the teaser stills show impressively exothermic reactions, like the reduction of lead oxide with aluminum to get metallic lead or what happens when rubidium and water get together. Some of this is serious “do not try this at home” stuff, but there’s no denying the appeal of watching stuff blow up.

As for [Taavi]’s supercap, we’ve seen a few applications for them before, like this hybrid scooter. [Taavi] may also want to earn points for Tic Tac hacks by pairing his supercapacitor with this Tic Tac clock.

[Thanks, Lloyd!]

Manipulating Matter In A Digital Way

On a fundamental level a computer’s processor is composed of logic gates. These gates use the presence of electricity and lack thereof to represent a binary system of ones and zeros. You say “we already know this!” But have you ever considered the idea of using something other than electricity to make binary computations? Well, a team at Stanford University has. They’re using tiny droplets of water and bar magnets to make logic gates.

Their goal is not to manipulate information or to compete with modern ‘electrical’ computers. Instead, they’re aiming to manipulate matter in a logical way. Water droplets are like little bags that can carry an assortment of other molecules making the applications far reaching. In biology for instance, information is exchanged via Action Potentials – which are electrical and chemical spikes. We have the electrical part down. This technology could lead to harnessing the chemical part as well.

Be sure to check out the video below, as they explain their “water computer” in more detail.

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A Thermometer Probe For A Hotplate, Plugging Stuff Into Random Holes

[NurdRage], YouTube’s most famous chemist with a pitch-shifted voice, is back with one of our favorite pastimes: buying cheap equipment and tools, reading poorly translated manuals, and figuring out how to do something with no instructions at all.

[NurdRage] recently picked up a magnetic stirrer and hotplate. It’s been working great so far, but it lacks a thermometer probe. [NurdRage] thought he was getting one with the hotplate when he ordered it, he just never received one. Contacting the seller didn’t elicit a response, and reading the terribly translated manual didn’t even reveal who the manufacturer was. Figuring this was a knock-off, a bit more research revealed this hotplate was a copy of a SCILOGEX hotplate. The SCILOGEX temperature probe would cost $161 USD. That’s not cool.

The temperature probe was listed in the manual as a PT1000 sensor; a platinum-based RTD with a resistance of 1000Ω at 0°C. If this assumption was correct, the pinout for the temperature probe connector can be determined by sticking a 1kΩ resistor in the connector. When the hotplate reads 0ºC, that’s the wires the temperature probe connects to.

With the proper pin connectors found, [NurdRage] picked up a PT1000 on eBay for a few dollars, grabbed a DIN-5 connector from a 20 year old keyboard, and connected everything together. The sensor was encased in a pipette, and the bundle of wires snaked down piece of vinyl tube.

For $20 in parts, [NurdRage] managed to avoid paying $161 for the real thing. It works just as good as the stock, commercial unit, and it makes for a great video. Check that out below.

Thanks [CyberDjay] for the tip.

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Gunpowder From Urine, Fighting A Gorn

[Cody] has a nice little ranch in the middle of nowhere, a rifle, and a supply of ammunition. That’s just fine for the zombie apocalypse, but he doesn’t have an infinite supply of ammo. Twenty years after Z-day, he may find himself without any way to defend himself. How to fix that problem? He needs gunpowder. How do you make that? Here’s a plastic jug.

There are three ingredients required to make gunpowder – saltpeter, charcoal, and sulfur. The last two ingredients are easy enough if you have trees and a mine like [Cody], but saltpeter, the a source of nitrates, aren’t really found in nature. You can make nitrates from atmospheric nitrogen if you have enough energy, but [Cody] is going low tech for this experiment. He’s saving up his own urine in a compost pile, also called a niter bed. It’s as simple as putting a few grass clippings and straw on a plastic tarp, peeing on it for a few months, and waiting for nitrogen-fixing to do their thing.

Calcium Nitrate

[Cody] doesn’t have to wait a year for his compost pile to become saturated with nitrates. He has another compost pile that has been going for about 18 months, and this is good enough for an experiment in extracting calcium nitrate. After soaking and straining this bit of compost, [Cody] is left with a solution of something that has calcium nitrate in it. This is converted to potassium nitrate – or saltpeter – by running it through wood ash. After drying out this mess of liquid, [Cody] is left with something that burns with the addition of a little carbon.

With a source of saltpeter, [Cody] only needs charcoal and sulfur to make gunpowder. Charcoal is easy enough to source, and [Cody] has a mine with lead sulfide. He can’t quite extract sulfur from his ore, so instead he goes with another catalyst – red iron oxide, or rust.

The three ingredients are combined, and [Cody] decides it’s time for a test. He has a homebuilt musket, or a piece of pipe welded at one end with a touch hole, and has a big lead ball. With his homebrew gunpowder, this musket actually works. The lead ball doesn’t fly very far, but it’s enough to put a dent in a zombie or deer; not bad for something made out of compost.

Historically, this is a pretty odd way of making gunpowder. For most of history, people with guns have also had a source of saltpeter. During the Napoleonic Wars, however, France could not import gunpowder or saltpeter and took to collecting urine from soldiers and livestock. This source of nitrates was collected, converted from calcium nitrate to potassium nitrate, and combined with charcoal and sulfur to field armies.

Still, [Cody] has a great example of what can be done using traditional methods, and the fact that he can fire a ball down a barrel is proof enough that the niter bed he’s peeing in will produce even better gunpowder.

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Anodized Phone Mount For Your Bike

There’s a slew of apps out there for tracking your bike rides. If you want to monitor your ride while using the app, you’ll need it securely affixed to your bike. That’s where [Gord]’s No Dropped Calls build comes in. This aluminium mount was hand milled and anodized, which gives it a professional finish.

The mount consists of 3 parts which were machined out of stock 6061 aluminium. The plans were dreamt up in [Gord]’s head, and not drawn out, but the build log gives a good summary of the process. By milling away all of the unnecessary material, the weight of the mount was minimized.

Once the aluminium parts were finished, they were anodized. Anodization is a process that accelerates the oxidization of aluminum, creating a protective layer of aluminium oxide. [Greg] does this with a bucket of sulphuric acid and a power supply. Once the anodization is complete, the part is dyed for coloring. If you’re interested, [Gord] has a detailed writeup on home anodization.

The final product looks great, puts the phone within reach while biking, and prevents phone damage due to “dropped calls.”