back in the 50's when i was just getting into the hobby of electronics we
used
neons as voltage regulator for screen voltage and as tone generators for
code
practice oscillators,
some where in my collection of paper i have a circuit that i built with 16
neons
and it set on my work bench for years blinking away and it would randomly
change sequence.
it was powered from a line voltage supply.
de Jx


> [Original Message]
> From: William \"Chops\" Westfield <westfw@mac.com>
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Date: 9/30/2007 8:14:53 PM
> Subject: Re: [EE] Neon lamps
>
>
> On Sep 30, 2007, at 5:41 PM, David VanHorn wrote:
>
> > So all those schematics I saw over the years, they were either wrong,
> > or assuming internal resistors in the lamps, yet I'm SURE I have seen
> > magazine articles with them where there was clearly no resistor.
>
> The circuits you're talking about were the pre-LED, pre- 
> microcontroller "blink light" circuits, and current limiting  
> resistors for the Neon bulbs were somewhat less common than they are  
> in todays projects that drive LEDs from a microcontroller with no  
> current limiting resistors.  I don't think that should be a BIG  
> surprise.  There was no internet in those days to report problems  
> with the Neon bulbs after a few hours of operation :-)
>
> On the other hand, you may have problems with aged neon bulbs.  I  
> wouldn't have thought that this would be a particular failure mode as  
> bulbs got older, but I doubt that there's very much real data on how  
> neon bulbs behave after a few decades (who knows HOW old neon bulbs  
> you buy these days are.  I know how old the ones in my junkbox are!)
>
> Were there ever any "professional" circuits that relied on the  
> negative resistance behavior of neon bulbs?  I don't recall seeing  
> anything other than use as indicator lights or "novelty flashers."
>
> BillW
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