[time-nuts] GPS for Nixie Clock

David davidwhess at gmail.com
Sat Jul 16 11:36:19 EDT 2016

The point of measuring the actual ignition point is to predictably
remove delay by driving the element earlier.  CRT grid structures
support transition times in the 5 to 20 nanosecond range; the smaller
distances involved with a nixie tube should support faster operation.

Something which just occurred to me is that ultraviolet can be used to
provide ionization to the gas without radioactivity.  Flame detector
tubes work like this so bathe the tubes in a small amount of UV.  I do
not know how transparent the nixie tube envelope to UV is though.

On Sat, 16 Jul 2016 11:04:22 -0400, you wrote:

>Since we have moved into synchronizing this stuff at the nanosecond level 
>(maybe we are even lower than that by now ..), simply getting a wide band
>enough signal off of a Nixe socket is going to be “interesting”. An array of picosecond
>photo diodes on each tube may be the only way to go. How many channels 
>this all will take depends a bit on how many digits past the second the display
>will show. Is it 9 digits past the second? 
>Since you will only know the ignition point *after* it has happened, the system
>only works to a certain degree. Trigger point *is* dependent on the light level. 
>You will need to collect real time data to keep things consistent. 
>> On Jul 16, 2016, at 10:49 AM, David <davidwhess at gmail.com> wrote:
>> Use AC coupling to each digit to measure the ignition waveform and
>> detect the breakdown point like with a tunnel diode trigger.  Use a
>> higher compliance voltage and greater negative resistance (constant
>> current drive?) to lower breakdown jitter.

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