[AMRadio] Negative Resistance Oscillators


Robert Nickels w9ran at oneradio.net
Sun Jan 20 22:28:55 EST 2008


I've been having a lot of fun experimenting with zinc negative
resistance oscillators.   I've used tips from K7NS, Nyle Steiner's
"Spark Bang Buzz" website:  http://home.earthlink.net/~lenyr/zincosc.htm
to create working audio and RF oscillators using negative resistance
devices made from galvanized sheet metal.   While it takes patience to
find the sensitive zinc oxide spots and the power level is very low,
they do work surprisingly well.

K7NS used an LC circuit to make an oscillator on the broadcast band, but
I thought crystal control would be interesting to try, and to my
delight, the output is clean and stable.  I've had success with both an
old 1196 khz crystal that I had in my junkbox, and a 3.58 mhz TV color
crystal.  It's definitely QRPp, but coupled to an antenna, the signal
can be heard around the house.  I've also had good results using a
backwards audio-output transformer fed from a CD player as an AM
modulator.  It's pretty cool to transmit music with good fidelity using
a transmitter made our of junk!

Take a look at my short video:  http://www.youtube.com/watch?v=cDBpBYkRw0Q

I'd love to hear from others who are interested in experimenting with
this kind of stuff.

73, Bob W9RAN


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