Radio overview Crystal radio

This was a great fun project to do. Just to assemble your components from scrap materials, fitting it all together and in the end your really get some sound out of it, how rewarding!

Vario capacitor Making the vario capacitor was the hardest part to do. The component actually is quiet simple but it takes a lot of labour to make all the plates and fitting it together. Especially when you don't know what you are doing. I mean i knew how it should look like and how to make one but will it have also the right capacitance? Hard to tell. Just trail and error here.

Vario capacitor I had finished a nice stack of plates and assembled it looked really nice. However i had to toss out a few plates because the capacitor became to large to fit in the box i had.

Capacitors After the adventure of making a variable capacitor i didn't like to make yet another one for the antenna coupling. To have some variation in the design i opted for a switch and to make three fixed value capacitors. Here again i had the problem that i don't know the capacitance of the end product when it's done. I made several of them just to compare them to known values. I rolled a few and i folded a few capacitors but none gave me the feeling that it was the right design. They where to flimsy, the wires cames loose or just plain ugly.

Spiderweb coil Because the previously wound coil didn't fit into the box i wanted to use a spiderweb coil design. I use a transparant cover so the coil is visible but well protected. I made 5 taps on the coil for band selection. The coil itself is wound on a frame made from a old CD.

Homemade diode Then there is this most mysterious part in the radio, the diode. I use two germanium diodes in the design which each drives a seperate high impendence ear piece. This way you can listen more comfortable. There is also the possibility to switch over to use a so called 'cats wiskher' detector. The crystal used in this component is where the radio got its name from. As you could have read on my blog i used different types of oxides such as copper oxide and steel oxide with mixed results. Used tools In this detector i use a small piece of pyrite which is commonly know as 'fools gold'. I was stunned how easily i could find hot spots on the crystal and how loud the signal is. The crystal is atleast as good as the bought geranium diodes or maybe even better.

Now you may wonder what tools i used for all of this? Here they are on one image. I only forgot to add a hammer and scissors to the image.