The Mayor of Silverton, Oregon is a hacker and wants to use roll-your-own hardware in the town’s parking meters. It’s not that he thinks he can do a better job than companies selling modern meters (although there have been notable problems with those), but he wants to retain the sentiment of the 1940’s era parking meters that are being replaced. Those meters are known as penny parking meters, because you can get 12 minutes of time for just one penny.
Many municipalities have gone digital with parking payment systems due to costs associated with servicing mechanical meters and collecting coins from each one of them. This hack aims to keep the look of the vintage meters, but replace the mechanical readout with a digital screen. The meter would still offer a reasonable parking deal; five minutes for free. Cost for replacing the internals is estimated at $150 per meter… which seems just a bit high if they are looking at a 250 unit run. The main problem that we see with the idea is that the original parking meter bodies don’t have a slot which can accept quarters.
[Jeri Ellsworth] continues her experiments with electroluminescence, this time she’s making EL ink. The ink she’s looking for is Zinc Sulfate in a solution. The process she chose is to re-dope some glow powder so that it can be excited by the field around an AC current. In her video (embedded after the break) she talks about the chemical properties she’s after by detailing a cubic lattice of zinc and sulfur atoms with an added copper atom (adding that atom is a process called doping).
The quick and dirty synopsis of the experiment starts by washing the glow powder with dish soap to acquire zinc sulfide crystals. Then she combined copper sulfate and zinc shavings from the inside of a modern penny to yield copper metal and zinc sulfate suspended in solution. That was mixed with the zinc sulfide from the glow powder washing and doped with a little more copper sulfate. The excess liquid is poured off, the test tube is capped with glass frit, and the whole thing hits the kiln to start the reaction. The result glows when excited by alternating current, but could have been improved by adding chlorine atoms into the mix.
We’re excited every time we see one of [Jeri’s] new chemistry hacks. We’d love to see more so if you’ve come across interesting chemistry experiments during your Internet travels, please let us know about them. Just make sure you have some idea of what you’re doing when working with chemicals… safety first.
Continue reading “More EL chemistry: Luminescent ink”