[sdiy] Amps and neons - here's a good one!

[Eric Brombaugh]

On 02/11/2013 11:32 AM, rburnett at richieburnett.co.uk wrote:
> As the neon bulb ages it's striking voltage increases.  Eventually the
> 340V peaks of the mains supply (or 156V if you live in US) will not be
> sufficient to strike a glow discharge in the gas.  However, if vibration
> even momentarily reduces the gap between the electrodes then a discharge
> will be initiated at a lower voltage.  Once the plasma has struck it
> will remain lit for the rest of the mains cycle until the current goes
> through zero extinguishing the arc.  Old neon bulbs frequently flicker
> in an unstable manner when there is barely sufficient voltage available
> to reliably strike the glow discharge in the gas.

Didn't they treat the neon electrodes with polonium at one point 
(perhaps still)? The polonium alpha decay ionizes the gas and allows it 
to strike more reliably, but as the polonium ages there are fewer decay 
events per time and eventually they happen so seldom that you see flicker.

I remember in Junior High science class we made cloud chambers and used 
what looked like neon electrodes as particle sources...

Eric