A New Experiment in Vintage Electronics,
The Medieval Age of Tube Radio, crossed with Leon Theremin's zen
simplicity.
This Tri-Min has three radio oscillators that control a Green CRT
tube. It is very sensitive to human movement, capacitance, and it
heavily interacts with a wide range of stations on the AM band. As
Shown, it has steel peacocks acting as antennae. It has no "audio out";
it is played by moving portable transistor radios within range. It is
solid wood "3rd World resourcefulness", with some clear "That 70s Show"
plastic, as well as vintage tubes and knobs. Thanks to Dan Conrad and
the Baltimore City Schools for letting me reuse stuff that would be
thrown away!
It is quite hard to describe what it does, only that you can dance
around it and the green ghost will follow your dance. In the viewing
window, you can monitor the red glow of the tubes.
Here is a detail of one side. Note the turned-wood, hand-wound coil
in the center. There is an antenna connection as well as modulation
output for weaving the signals.
Here is a simplified schematic of the radio circuits. (click for
larger view). Each hartley oscillator has a 50:100 coil of fine wire
and a variable capacitor. It is buffered by a second triode, which then
feeds a mixer pentode (note there should be a 1M resistor on the
pentode grid and supressor). The output of each mixer pentode goes to
the CRT as X, Y, and Z (intensity). Thus you see a woven pattern based
on the interactions of the three radios.
For the CRT tube I used a 5CP1 for which I also salvaged a
heavy-ass transformer, which generates the +1500 and -1500 volts for
Anode and Cathode, as well as +400 volts for everything else. I have a
dream of making such high voltage stuff with silicon solar panels,
converting high current to high voltage via switching inductance.
Here is the first prototype, horizontal projecting tri-min. Similar
schematic, except the variable capacitors all feed back into each
other. Much more chaotic.
Start planting!! Enjoy weeds!! Cactus barbs are sharp!! Relish the
romanticism of dinosaurs without burning their bodies!!