In the previous post I've presented a simple way of extraction compounds from ashes, today I will measure radioactivity of obtained sample by using my homemade Geiger counter. Below is a quick view of the setup that I used.
Organisms are built mainly of carbon, hydrogen and oxygen, but they use many more chemical elements, one of them is potassium. After burning of organic matter, potassium stays in ashes as oxide that later is transformed to hydroxide. In the environment, potassium exists in a mixture of three isotopes: 93.3% of 39 K, 6,7% of 41 K, and 0,012% of radioisotope 40 K. The amount of mentioned 40 K radioisotope is really tinny, but sufficient to be detected using home methods.
In this post I will present a simple method to extract potassium compounds from ashes. Purity of the end product is low, from what I found online, for wood ashes, it's around 20-30%.
What is needed? Cigarette ash (for this experiment I used remains of 192 cigarettes - I'm a smoker!), water (can be tap water), stove, pot, two beakers (or jars), funnel, cotton, stirrer (or spoon). The whole process takes a couple of hours.
I've started from removing cigarette buts, matches, and other junks, the result was ~130ml of ashes.
A simple but useful breadboard can be made at home, it will be more expensive than those on the markets, but it's possible to add commonly used elements, like LEDs, switches, etc.
I hadn't had female sockets, so I cut in half old DIP-18 sockets - it works OK.
The bottom layer was coated with Lichtenberg's alloy - it's an easy and elegant way to protect traces from dust, humidity or oxidation.
The circuit looks like a monster, but there isn't a lot of logic - only sockets, and a couple of LEDs - I didn't want to add more components, at least in this version.
Li-ion cells become more and more popular due to their capacity and reasonable prices. In this entry I will show how to build a simple li-ion battery charger based on MCP73831 chip. It's a quite useful device for DYI projects,in addition its cost is only around 1,5 euro.
The device uses USB port as a power supply (mini-USB connector). I use the standard gold-pins as an output socket. There're three of them, but only two are used (looking on the image, counting from top: V+, V-). I will design my li-ion based devices in the same way (same socket, but female), then if I will connect it in the incorrect direction (rotated 180 degrees) they won't be damaged (V- connected to V-, but V+ connected to n/c pin) - simple way to avoid plugging in an incorrect way.
LED indicates if battery charging is in progress.
Pay attention to connection polarity, li-ion batteries can burn or explode if connected incorrectly. Never leave battery unattended while charging is in progress.
The PCB could be smaller, but it's made in this shape according to chip's documentation, additional copper space is used to dispatch heat produced during charging. The documentation mentioned 2-side layout, but I used only one side. The copper was coated by using Lichtenberg's alloy, so heat dispersion is improved - it seems that it's enough.
Eagle files can be downloaded from my GitHub.
That's all, I will use this tool while upgrading my Evaluation board for DYI robots and . I will also have to thing about some DC/DC converter for them (to obtain 5V from li-ion battery), but that's a different story.
It's not possible to protect an image against any person, but it can be protected enough for most of the users. There are a couple of ways to do this, most popular are CSS tricks, but today I will present another way.
Can you save below image? I bet you can't! ;-)