Thanks for your extended reply. Highly interesting ! I didn't know about the Solartron problems, was even in the mind they where of good quality (However, never used one).
The fact the circuitry is very complex I already suspected. I put aside a plan to make a graphics card, end seventies, for that reason, despite it was a design in a magazine. Trying to develop a digital clock with analogue scales as read out, I know what your experience will have been during developing this clock ! eric -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of morrisodell Sent: donderdag 5 april 2012 11:36 To: neonixie-l Subject: [neonixie-l] Re: Scope clock with a difference That tube uses the standard P7 (or P in the European nomenclature) phosphor which is a 2 stage system. There's a blue/UV short persistence layer which excites a greenish long persistence layer. They are usually mounted with an orange filter to suppress the bright blue flash which some people find unpleasant. I think there are also very long persistence orange phosphors which work the same way - I have a couple of old radar display units with such tubes which I plan to make into clocks but they both use magnetic deflection so lots of developmental work to do! One of them has a rotating yoke and the other a static one. I'm not 100% sure why the circle is not perfect. I suspect it's because of nonlinearity or marginal headroom in the deflection amplifiers. I'm running the CRT at 4 kV which maximizes the required swing for deflection voltage. I used a different design in this clock from a previous P1 clock which did display a perfect circle. This one has a differential cascode topology with a CA3054 chip for the long tailed pair and a couple of MJE340s for the common base level shifters. At least there's no thermal drift and excellent common mode rejection allowing the use of a very simple power supply. Incidentally I was driven crazy while developing this clock because I was using an old Solartron scope which had a P7 CRT for a test bed . I couldn't get the origin of the hands to stop rotating with the scan. It turned out to be the very poorly designed deflection amplifiers in the scope that were at fault. It's amazing to compare what Tektronix was doing at the same time in the 1960s. Such a thing would never have happened with one of their scopes. Crap British engineering of the 60s wasn't just confined to their cars :-) I don't have any plans to produce boards or designs for this clock. It's very complex and uses boards with bits of circuitry from other clocks I've made. I'm happy to give advice though. I think the design is half the fun! Morris On Apr 4, 10:03 pm, "Tidak Ada" <[email protected]> wrote: > Intriguing design ! > Aren't there also tubes with orange luminance and green > phosphorescence or isn't that the right phosphorescence time ? I > should like that colour combination. > Sorry for my lack in knowledge, but what is the reason the clock isn't > exactly smooth round. Is that a technical difficulty ? > > eric > > > > > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On > > Behalf Of Dan Harboe Burer > Sent: woensdag 4 april 2012 13:01 > To: [email protected] > Subject: Re: [neonixie-l] Re: Scope clock with a difference > > Wow. Impressed I am. > I would love to build a clock like that :o) > > Dan > > ----- Original Message ----- > From: "morrisodell" <[email protected]> > To: "neonixie-l" <[email protected]> > Sent: Wednesday, April 04, 2012 12:55 PM > Subject: [neonixie-l] Re: Scope clock with a difference > > Hi all, > > Here is the radar clock again, pretty well in its final form. The HV > wire to the CRT needs tidying up before it can be make a safe debut > :-) > > http://youtu.be/Jjs7AWL8B1k > > Morris > > On Mar 6, 7:27 pm, morrisodell <[email protected]> wrote: > > Hi all, > > > Here is a video of the prototype of my latest clock. It's a GPS > > locked scope clock with a PPI radar type display using a CRT with a > > P7 type long persistence screen. I haven't finished packaging it up > > yet and the display should be a little better once the power > > transformer fields are shielded by the steel case. The focus is > > razor sharp but the iPhone I used to take the video didn't focus well in the dark. > > >http://youtu.be/RnsaXkfxygo > > > Enjoy! > > > Morris > > -- > 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 > [email protected]. > For more options, visit this group athttp://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 [email protected]. For more options, visit this group at 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]. 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