Neon bulb logic elements link?

Eric Smith eric at brouhaha.com
Wed May 25 17:48:06 CDT 2005


I wrote:
> You turn on a particular tube by dropping the X line to 0V and raising
> the Y line to +105V.  The selected tube sees 105V, while the other tubes
> in the same row and column see 97.5V.

Tom wrote:
> I think your idea is generally right, but this detail seems wrong:
> when X goes from +7.5V to 0V, the entire line will see 105V,
> striking the entire line.

Nope.

                  7.5V            0V

                   X0             X1
                    |              |
                    |              |
 97.5V  Y0 --------90V-----------97.5V
                    |              |
                    |              |
105.0V  Y1 --------97.5V----------105V


Locations (0,0), (1,0), and (1,0) are all still below the strike
voltage.


For turning off location (1,1):

                  7.5V           15V

                   X0             X1
                    |              |
                    |              |
 97.5V  Y0 --------90V-----------82.5V
                    |              |
                    |              |
 90.0V  Y1 --------82.5V----------75V

Locations (0,0), (1,0), and (1,1) are still above the maintain
voltage.


Analysis is easier if you center the voltages around zero, as
in my later posting.  My original numbers are centered but with
a fixed DC offset.

I wrote:
> Will neon bulbs have reduced lifetime if you run them on DC?

Tom wrote:
> As far as I can tell from reading literature, basically the metal
> electrodes develop non-conducting surfaces (eg. oxidation) from
> impurities in and outgassing from the glass and metal.

Chicago Miniature Lamp says that DC operating life is 60% of AC.
However, the lifetime specs given for "circuit element" lamps (as
opposed to "indicator") are for DC.

Eric



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