Our Name In Lights...... (??)

[Dave Halliday]

>     OK, I'm gonna finally bite.
>     What the heck is a neon light synthesizer?  Does it oscillate once 
>     every thirty seconds, and spell out a blinking "Eat at Joe's"?  Does 
>     it respond to dance disco balls, with pulsating sequences?  Or does it 
>     actually spell the synthesist's name out in neon lights?  (I'm 
>     clinging to this rather egotistical notion, but then again, I'm a 
>     musician, not an engineer). 

Back a little after computers were still wood-burning and before we 
started carving our own IC's out of blocks of wood, there were neon 
lamps.  These ran just fine on 120 volts and were used a lot as power 
indicators.  Long life, cool operation.


They were effectivly a total insulator - two terminals sticking up 
into a little chunk of Neon gas.  You could put a voltage across them 
and nothing would happen *until* you hit about 70 volts or so and at 
that time, you proceeded to brutally rip the electrons off the outer 
few shells and whammo - your neon started conducting and it would give 
off a bright orange glow.

Because there was such a sudden threshold between off and on in terms 
of electical resistance, you had to run the lamp with a current 
limiting resistor in series when you were running it from 110.
something in the order of 220,000 Ohms if memory serves...


ANother neat trick is that you could have a source of about 100 volts 
DC, connect this source through a largish resistor to a capacitor and 
place a neon lamp in parallel with the capacitor.

The capacitor would charge until the neon lamp fired, shorting out the 
capacitor and the capacitor would then charge until the neon lamp 
fire, shorting out the capacitor and the capa...

You get the picture!  <g>

Make the value of R and of C small enough and this starts happening in 
the audio frequency range.




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