The AC input has 2 fuses (3/8 amp fast-blo on the hot and neutral lines), and 2 resistors (33 ohm, 1/4 watt). Any one of them will blow to open the circuit (never happened). Yes, it's a hot-chassis design but so are many other devices. There is sheet-metal shrouding to protect from an internal fire (never happened).
I always suspected you could safely run CMOS IC's directly on the AC line, and that was one of the goals of the design, not just to build a nixie-tube clock. I also did all of the CAD work (PCB design, logic simulation, schematic capture) with free software on a PC that I literally had thrown into the trash, but had second thoughts because I knew that PC still had a useful purpose (it's 19 years old now, and still running....). That was another design goal. On Saturday, May 22, 2021 at 10:59:27 AM UTC-7 newxito wrote: > No transformer? Well, that's scary indeed :-) > I almost don't dare to ask... does it have a fuse? > > > gregebert schrieb am Samstag, 22. Mai 2021 um 19:27:51 UTC+2: > >> My first nixie clock uses 4000-series CMOS, and is AC-line powered. Not >> just the power ( *without* a transformer), but also the timing. There is >> a battery-backup oscillator. I built 2 in 2011, and our 2 kids each built >> one. All 4 are still running just fine. They can display 12hr or 24-hour >> mode. >> >> I simulated the design in verilog so there were no logic errors or fixes >> on the PC boards. >> >> On Saturday, May 22, 2021 at 7:25:26 AM UTC-7 newxito wrote: >> >>> Small typo sorry, the youtube channel is called CuriousMarc.... >>> >>> My "creepy clock" from 2016 still works and I turn it on from time to >>> time, but only while I'm in the room :-) >>> >>> >>> >>> J Forbes schrieb am Samstag, 22. Mai 2021 um 14:38:11 UTC+2: >>> >>>> I dind't design the logic myself, I used a design from the TTL >>>> applications book by Texas Instruments. But the clock is still around, >>>> twenty years later. I don't leave it running, it's kind of scary. >>>> >>>> http://selectric.org/nixie/index.html >>>> >>>> and scroll down to the bottom of the page >>>> >>>> On Friday, May 21, 2021 at 11:48:58 AM UTC-7 newxito wrote: >>>> >>>>> I always wanted to design a nixie clock that uses just 74xx ICs. I >>>>> know that there are some schematics available but just copying a design >>>>> is >>>>> not fun. >>>>> >>>>> Recently, I watched a video from CouriousMarc with an intro to a >>>>> digital logic circuit simulation software called logisim-evolution. I >>>>> think >>>>> that will be a big help, the software looks great! >>>>> >>>> -- 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/6fcaacd6-b85f-4e57-a90e-7550ab91a6den%40googlegroups.com.
