Narrow-Bandwidth Television Association

I got interested in making a home made type of Semiconductor made from in my case a galvanized nail .

I think its pretty interesting making an oscillator from a 2 pin device that you can make from junk .

How its made is you have to heat the nail with propane torch ,,,,,,on the other side around the nail zinc oxide is formed when it cools down and black spot of negative resistance you can see and some times not .

I also found if you don't have a torch a welder works as well with short welds to the nail it heats it enough to form the stuff .


Heres the circuit i am using apart from the rf part V cap and coil just doing AF ,the other coils in the picture are my magnetic amp transformers i am working on .

I am using more voltage than in the schematic 12 to 24 volts in the larger video you can see how touchy it is to adjust to get going ...also the wave form gos from nice sine wave to something a little more messy i suppose it could be the wire touching more than one negative resistance spot on the nail .

I saw one fellows design he had puts hes device in a large glass fuse to keep if safe ,i like that idea !

Most others i have seen doing this use galvanized sheets cut thin to make the device and i can say thin is good heating the metal would be harder if to thick ..it has to get pretty hot to the point the zinc starts to spit then you know its made the negative resistance dark spots on the metal ...

Simple thing but it is touchy to work out .

Still playing around with the zinc oscillator and tried to make a compact housed version but they are so touchy a little knock and it stops working .

The plan was to line it up working and hot glue it in place well the working part works gluing part not so good !

i made a few different versions to try but i think as in the old cat's whisker detector i think you really need the adjustments for something like this after trying a few times .

One last thing i tried a trany on the circuit just using the collector and emitter and that worked as well .

Home made parts are interesting but hard

Homebrew parts may be hard, but darn do they look cool! Those ones in the fuses look totally pro

Metallica Man X wrote:Homebrew parts may be hard, but darn do they look cool! Those ones in the fuses look totally pro

Very very hard my friend and a touch frustrating in the mix as well.

The Tiny fuse worked for a bit i was trying little cut out bits of zinc cut up nails what ever i had ..trouble is you need to hit just the right spot for it to work ...and just touching ever so slightly even at that .

I think its working via the negative resistance spots on the zinc like a very close spark gap or it seems like that ...

The last go i was hopeful for a housed working version but again very frustrating i know how those people who made early crystal radios must of felt like trying to adjust it to work ...oh well a bit side tracked off the magnetic amp just wanted to see if i could make a useful oscillator apart from the generator .

BTW the floppy drive generator gives at least 120 volts it will partly light a 240 volt globe .