Dylan,
The main design flaw with the published trigger tube clock is the change
of supply voltage (I frigged the anode resistor to compensate). This
does effect the pulse carry timing considerably. The main problem
with the XC18 is it requires light to trigger reliably - leave the clock
in a dark room and one or more rings will have failed by the morning.
Tubes with a keep alive electrode like the Z700U will operate in
complete darkness. My own XC18 clock is now just a demonstration clock
that I fire up just to show it off as and when.
I have a design for a second XC18 clock with schematics and layouts done
in Eagle which I can email to you if you want to see them? This will
give you a (all valve) design of a stabilised PSU and a 50 (or 60) Hz to
1 Hz divider using a two stage phantasmagorical divider which has a
pulse shaper at the end to drive a XC18.
For a more back-to-basics on trigger tube circuit design then download
this book by Neale (86MB) chapter 5 in particular:
http://www.sgitheach.org.uk/dmneale.pdf
As it goes through the design process for trigger tubes (it uses the
Z700U in the worked example).
As a general comment to anyone on the list it is an ebook worth having IMHO.
Building dividers on a breadboard is very easy and work well. The first
divider I built was a two tube, divide by two, and then I added several
more stages just to watch it count. I used a simple neon relaxtion
oscillator to provide a slow enough tick that the dividers could be seen
to be working rather than just using a 'scope.
There are other XC18 clocks out there but all have the same darkness
problem so must be kept lit. A few UV leds seem to work fine but the
holy grail of an all valve clock has perhaps then been lost.
The clock web page now lives on my own website as well
http://www.sgitheach.org.uk/nixie3.html
Happy to correspond, and I'm sure others will have comments as well.
Cheers Grahame
On 09/05/2012 18:32, Dylan Distasio wrote:
Hi all-
I recently picked up some XC18 trigger tubes in the hope of eventually
building a trigger tube clock inspired by Grahame's work
http://www.neonixie.com/trigger-tube-clock/Trigger_Clock.pdf.
I have reviewed some of the basic trigger tube circuits out there, but
was hoping someone with experience using trigger tubes could provide
some additional guidance.
I am interested in building a simple ring counter circuit on a
breadboard but wasn't sure what resistor / capacitor values to use,
and an input for the trigger. I will probably eventually use the
mains frequency in the clock, but am open to suggestions on another
source for testing. Any help on the simplest possible ring counter
circuit possible with these tubes and other tips would be greatly
appreciated.
Thanks,
Dylan
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