Strange modulation schemes & Chaos
dave.halliday at greymatter.com
Fri Jun 27 04:56:20 CEST 1997
> Dan Slater wrote:
> These instruments produce various oscillations
> and noises and which are controlled by how the instrument is
> illuminated. The weak magnetic field causes the electrons emitted by
> the photocathode to spiral apparently using a mechanism similar to
> that of a microwave magnetron.
> There were special digital decimal counter tubes made in the
> 1950s-60s by Burroughs which exploited this effect. The magnetic
> field caused the electrons to describe a mathematical curve
> called a TROCHOID. Thus, the tubes were called "Trochotrons".
> The first version was the 6700, a big glass tube with 27 pins and
> surrounded by a large cylindrical alnico magnet. Later versions
> incorporated small magnets INSIDE the tube and were called "Beam-X"
> counter tubes. Quite ingenious--supposedly able to count at up to
> 2 MHz. I have some....thinking of making a tube sequencer with one....
> (they directly drive Nixie display tubes too!)
I remeber seeing them on lab equipment in the 50's and 60's.
My dad is a physicist and I would visit the labs whenever I could.
Scalars and Counters were bit things back then.
I remember that these tubes were really expensive - I wanted to build
a counter for myself and they were the equivalent of a couple hundred
bucks each ( in todays money )
Wound up doing a binary counter with multivibrators
--- Via Silver Xpress V4.4 [Reg]
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