Kirlian photography - a simple way of taking it

Kirlian photography is an interesting photographic technique of capturing corona discharge of objects. The images basically contain only edges in a form of blue glow. Note: one of those photos is visible in "The X files" intro - read the whole article to know why!

In this post I will present my minimalist approach with common materials and without complicated construction. The results aren't that good as with more complex setups, but I think that they are still really interesting.

Materials

  • A camera with modifiable ISO and exposure time.
  • 10-30kV high voltage supply.
  • Tin foil. I used a foil in a form of adhesive strips because it's easier to stick it to surfaces, but a regular one can be also used.
  • Small piece of glass.
  • Slats or other things to put everything in place.

Old horror movies special effects or Jacob's ladder in action

In my previous post I've described a simple high voltage generator (10-30kV), today I will show how to use it to build a device that appeared many times in old horror movies, long before computer special effects. It was used to create interesting visual effects of sparks that went up and down.

This device is called Jacob's ladder and consists of two electrodes made from long wires formed in a V shape. When the high voltage is applied, an electric arc creates on the bottom (where the air gap between electrodes is smallest). When the air around the electric arc heats, it goes up like a balloon and also moves up the arc. When the distance between electrodes is too long, the arc breaks and the whole process repeats.

High voltage supply (10-30kV) made from CRT television flyback transformer

Old CRT monitor or TV is a great source of electronic components that can be used in DYI constructions. One of them is a flyback transformer that can provide 10-30kV output. The input voltage can be in a range from a couple of volts to over a dozen of volts, power consumption is a couple of watts. In my construction input voltage is 9V, power consumption is 5W.

A flyback transformer is driven by one or two transistors that should be also extracted from the same TV or monitor, those are high voltage transistors, that are hard to substitute and if bought separably can be expensive.

Geiger–Müller counter with three STS-5 lamps

The Geiger–Müller counter is a relatively simple tool to measure ionizing radiation. In today post I will present my construction of the Geiger–Müller counter that contains three soviet STS-5 lamp. I've used more than one because that increase sensitivity, that's important for me because I want to measure natural sources of (low) radiation like soil, rocks. I have also in plans building my home radiometric station (it would be part of part of a weather station) connected to the web, so I get the data wherever I am.

The electronic circuit of a Geiger–Müller counter

TODO: description.

Homemade Geiger–Müller simplified circuit

Waring! The device uses high voltage that can lead to injury or death when used inappropriately. Don't touch it when power is on, discharge capacitors after use or wait a couple of minutes.

Simple tool to deobfuscate JavaScript code

I've brought to life my old HDD, so I will share one of my old project that I've found there. It was originally shared on my first blog - it brings back memories :) So here it is (slightly modified).

Somewhere on my disc, I've found a page with an obfuscated JavaScript code, that you can see below. In this form it's completely unreadable, but this can be improved easily.

(function(){var s=true,t=false,aa=window,u=undefined,v=Math,ba="push",fa="slice",ga="cookie",y="charAt",z="indexOf",A="gaGlobal",ha="getTime",ja="toString",B="window",D="length",E="document",F="split",G="location",ka="href",H="substring",I="join",L="toLowerCase";var la="_gat",ma="_gaq",na="4.8.6",oa="_gaUserPrefs",pa="ioo",M="&",N="=",O="__utma=",qa="__utmb=",ra="__utmc=",sa="__utmk=",ta="__utmv=",ua="__utmz=",va="__utmx=",wa="GASO=";var xa=function(){var j=this,h=[],k="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";j.uc=function(m){h[m]=s};j.Nb=function(){for(var m=[],i=0;i<h[D];i++)if(h[i])m[v.floor(i/6)]^=1<<i%6;for(i=0;i<m[D];i++)m[i]=k[y](m[i]||0);return m[I]("")}},ya=new xa;function Q(j){ya.uc(j)};var za=function(j,h){var k=this;k.window=j;k.document=h},R=new za(aa,document);var Aa=function(j){return function(h,k,m){j[h]=function(){Q(k);return m.apply(j,arguments)};return m}},S=function(j){return u==j||"-"==j||""==j},T=function(j,h,k){var m="-",i;if(!S(j)&&!S(h)&&!S(k)){i=j[z](h);if(i>-1){k=j[z](k,i);if(k<0)k=j[D];m=j[H](i+h[z](N)+1,k)}}return m},Ba=function(j){var h=t,k=0,m,i;if(!S(j)){h=s;for(m=0;m<j[D];m++){i=j[y](m);k+="."==i?1:0;h=h&&k<=1&&(0==m&&"-"==i||".0123456789"[z](i)>-1)}}return h},U=function(j,h){var k=encodeURIComponent;if(k instanceof Function)return h?

[...]

USB powered thermometer with an interesting data display

Almost each person interested in building electronic devices has built at least one thermometer and power supply in his life. I'm not different, to add to this, today I will present one of my thermometers.

Original concept was different, I wanted to use it as a weather station, wake up, go to my balcony, smoke a cigarette and check what on this device what is the temperature, humidity and air pressure. At the end I decided to build a small thermometer (in future with all mentioned features), that I could plug to my computer and check conditions in my home.

What is nice here is that the data is displayed original way, there are two rows of nine LEDs, if on the upper row second diode is on, and on the bottom row fifth diode is on, then the value presented by the device is 2*10 + 5 = 25. It can sounds complicated at first, but in practice it's fast and intuitive. Below is an example, value presented on the display is 25:

USB heater for ant colonies

As some of you already know, I'm a big fan of ants and for one of my colony, I decided to make a heater. Today I will describe the current state of this device, however it's far from being finished. It uses a resistor that (as any other resistor) produce heat when current goes through it

Let's start from the theory, what should be the value of the resistor (resistor's max power and resistance) if it would be desirable to obtain as much power from USB as possible? The USB supplies always constant voltage (5V) and maximally it can supply 0.5A of current. The maximal power consumption of the device connected to the USB (a resistor in this case) is P=U*I = 5V*0.5A = 2.5W. From Ohm's law, R=U/I = 5V/0.5A = 10Ω.

I placed this resistor in gypsum form (created from matchbox, after it dried-out the paper was scratched out by using a knife).

Before even trying to connect it to the USB port, I verified if it works by using my lab power supply, it worked but I observed two negative things, the first one was the amount of power drained from power supply - was a bit too big, the second was that the heater heats itself way too much, it was too hot. That's why I plan to add some sort of PWM regulation to decrease power consumption, after that I think that it will be a quite useful gadget.