I built an XC18 clock based on Graham's design and can confirm, disappointingly, it won't work in the dark. I heard from an old friend of my father's, who used to work for Hivac, that these tubes were made with a small amount of radioactive material to assist with ionization, and presumably it's had enough half lives by now to be ineffective.
If anyone is interested, I will email them a copy of my schematics, which are closely similar to Graham's. I also have one spare PCB - I did the whole thing (less the power supply) on a single board ten inches by seven. Pete Hand On May 9, 12:10 pm, Dylan Distasio <[email protected]> wrote: > Thanks for the info and comments, Grahame. As an aside, I love your clock, > and your other interesting projects! > > I'll take a look at the book. If you wouldn't mind emailing me the design, > that would be great also. > > I will definitely take you up on your offer for continued correspondence as > I move forward. > > Best, > Dylan > > On Wed, May 9, 2012 at 2:16 PM, Grahame Marsh > <[email protected]>wrote: > > > > > > > > > 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<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<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<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 > >> -- > >> You received this message because you are subscribed to the Google Groups > >> "neonixie-l" group. > >> To post to this group, send an email to [email protected]. > >> To unsubscribe from this group, send email to neonixie-l+unsubscribe@** > >> googlegroups.com <neonixie-l%[email protected]>. > >> For more options, visit this group athttp://groups.google.com/** > >> group/neonixie-l?hl=en-GB<http://groups.google.com/group/neonixie-l?hl=en-GB> > >> . > > > -- > > You received this message because you are subscribed to the Google Groups > > "neonixie-l" group. > > To post to this group, send an email to [email protected]. > > To unsubscribe from this group, send email to neonixie-l+unsubscribe@** > > googlegroups.com <neonixie-l%[email protected]>. > > For more options, visit this group athttp://groups.google.com/** > > group/neonixie-l?hl=en-GB<http://groups.google.com/group/neonixie-l?hl=en-GB> > > . -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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