There are eight dekatrons in the circuit. The first (G1) divides the 60Hz signal by 6, giving a 10Hz signal. To change it to support 50 Hz, move the emitter of the PNP transistor of the reset circuitry to the "5" cathode (K5) of the dekatron. The furthest to the right "Witch Tube" (sic) note in the diagram refers to G1, the first divide-by-six dekatron. The second "Witch Tube" note referencing K8, K9, and K5 are for manually resetting the seconds counter to 59.8 seconds. K8 references G2, K9 references G3, and K5 references G4. Pressing the seconds reset button sends a 10Hz pulse to the indicated cathodes, setting them to 59.8. They'll then roll over to 00.0 after the button is released.
The high voltage target was at least 475v. I'm using a voltage tripler with a nominal 120v RMS at 60 Hz supply, giving 120v * 1.414 * 3 = 509v assuming no diode losses. I measure very close to 500v, due to the diode losses and the 22-ohm current limiting resistor. It's a 5 watt fusible link resistor I had laying around. The only polarized capacitors are in the power supply section, supplying +500v, +170v, -170v, and +40v. The zener diode for the +40v supply is actually a 39v zener, as 40v ones are very hard to find. A 39v supply is close enough to 40v for the dekatron. The "reset counter 60Hz? or Witch Tube" (sic) note references G4, the tens-of-seconds counter. When that counter reaches "6" it is reset back to zero. The complex reset circuitry furthest to the left detects when G7 reads "3" and G8 reads "1" (hour 13), sending a reset pulse to K1 of G7 and K0 of G8, reseting them to hour 01. The tens-of-hours dekatron spends a lot of time displaying "0", and I found that the K0 cathode would wear down. To extend the life of the Dekatron I connected the odd cathodes to the NPN driver for the zero cathode of the Nixie tube, and all the even cathodes to the NPN driver for the one cathode of the Nixie tube. Since all the even cathodes are connected together, sending a reset pulse moves the glow to a random even cathode. Advancing the tens-of-hours from there goes to a random odd cathode. Making the clock handle 24-hours instead of 12 hours is more difficult, as the simple even/odd grouping has to instead have three groups. In that case I'd leave the K9 cathode open and make groupings of K0, K3, K6 for "zero", K1, K4, K7 for "one", and K2, K5, K8 for "two". The reset connection to K3 on G7 would be moved to K4 on G7, the connection to K1 on G8 would move to K2 on G8, and the connection to K1 on G7 would move to K0 on G7. That would detect "24" on the hours and reset to "00". You'll also need another NPN driver for the "2" on the Nixie. Converting from 120v to 240v isn't as straight forward. You still need at least 475 volts for the Dekatrons, at least 170v for the Nixies, and a large negative voltage for the reset circuitry. The 39 volts for the Dekatron gates can be derived with a zener from the Nixie supply. First the voltage tripler has to be replaced with a doubler instead, giving 240v * 1.414 * 2 = 679v. The Nixie supply become 240v * 1.414 = 339v. You'll have to find higher-voltage capacitors for the supply filters and increase the anode resistors for the Dekatron and Nixies. The transistors used are rated for 300v (MPSA42 and MPSA92) and 450v (STQ3N45K3). Note that the MOSFET part number is incorrect in the diagram, it's STQ3N45K3 and not STQ3N4K3. All-in-all I think the easiest thing to do is use a travel transformer to change your supply from 240v to 120v, something like https://www.amazon.com/Watt-Step-Down-Converter-International/dp/B077CFPD1T/ref=sr_1_42 I did the same thing for a thyratron ring counter clock I built, the schematics were for a 240v 50Hz supply and I used a travel transformer to step up the US 120v 60Hz supply to 240v 60Hz. I had to change a divide-by-five counter to a divide-by-six, but that was easy in comparison to modifying the circuit to use 120v instead of 240v. Mike Mitchell On Friday, October 11, 2024 at 1:58:11 PM UTC-4 Benoit Tourret wrote: > I tried to better understand mike's drawing. > > what is exactly the purpose of the Dekatron 1 (in red) > I see G1 and G2 receiving the AC voltage. I guess it is 60 Hz? > I just have to use the pin K5 for 50 Hz ? > K1 is to reset the clock > K0 should activate the mosfet driving the second tube at 10 Hz > the second tube divide by 10 to send seconds. and so on until the end of > the day. do not pull the clock in water after midnight !!! Gremlins inside > !!! > > the columns are driven by tube 2 ? > > I am using 240 V, how should I adapt the power supply part ? > I see 500V on the power part and 475V on the Dekatron anode, this the same > ? > > [image: DSCN0009 copie.jpg] > > Well, I am far to be a Jedi... > > Regards, > Benoit. > Le dimanche 24 septembre 2023 à 19:29:33 UTC+2, Benoit Tourret a écrit : > >> [image: essai.jpg] >> >> >> Trying to make something more ... modern ??? >> >> it is the left part of the schematics. without the resistors on the A-101 >> ... I need to work on it. >> I am not sure that this project is the best to begin with kicad... >> Le samedi 23 septembre 2023 à 22:24:14 UTC+2, Benoit Tourret a écrit : >> >>> Thanks Mike and Terry. >>> >>> one of my friends cleaned up the plan a little, it's already easier to >>> read. >>> >>> [image: DSCN0009 copie (002).jpg] >>> >>> I will see witch method I will use for connect the A-101. >>> it will mainly depend on witch tube / socket I will use for the nixies... >>> >>> Regards, >>> Benoit. >>> >>> Le samedi 23 septembre 2023 à 19:17:41 UTC+2, Mac Doktor a écrit : >>> >>>> >>>> On Sep 22, 2023, at 2:44 PM, Benoit Tourret <[email protected]> >>>> wrote: >>>> >>>> How did you made the A-101 sockets ? >>>> >>>> >>>> Here's a complete guide to the method. It includes photos (scroll down >>>> a couple of pages): >>>> >>>> https://threeneurons.wordpress.com/arduino/dekatron-shield-kit/ >>>> >>>> >>>> There's a diagram that you can use to get the pattern for the holes: >>>> >>>> >>>> I built this kit. Don't make the mistake of sliding the pins all the >>>> way in the "tubes". It was a nightmare getting the Dekatron back out after >>>> soldering the female Molex connectors in place. I had to get a friend to >>>> do >>>> it for me. I would have destroyed it. >>>> >>>> >>>> Terry Bowman, KA4HJH >>>> "The Mac Doctor" >>>> >>>> https://www.astarcloseup.com >>>> >>>> Edward R. Murrow: “Who owns the patent on this vaccine?” >>>> Dr. Jonas Salk: “Well, the people, I would say. There is no patent. >>>> Could you patent the sun?”—*See It Now*, 12 April 1955 >>>> >>>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2568f28e-c84b-4a93-9a33-e00c4af5b71en%40googlegroups.com.
