Nixie digital stopwatch repair (DS35)

Fixing a digital stopwatch (or stopclock) with nixie tubes from the early 1980s made by ZPA Pragotron in Czechoslovakia. Exploring what's inside and how does it work, thermal imaging, explaining the schematic with a 7400 TTL logic, building a replacement for the missing remote control.

Please support my channel on Patreon:

This stopwatch on my website:

Instagram:

[emilstardust]

It's always nice to look at a Nixie clock while counting. In 1977 I have a Nixie digital clock in a discrete design (without IC) with around 150 transistors! built. I'm angry today that I threw them away. Many greetings from the Erzgebirge! Glück Auf!

[Ale.K]

Beautiful stopwatch, great repair! I'm glad it ended up in your hands and not turned into a clock...

[noakeswalker]

So nice to see nixie tube with a proper '5' digit ! Also, only you would have those hard to find nixie driver chips in your pile of bits - that was fixed easily. It's always amazing to me to see test gear from as late as the '80s still using nixies.

[tajtrlik]

Na video s týmto zariadením som sa veľmi tešil, predpokladal som, že ho niekedy vydáš, keď som v jednom tvojom staršom videu videl tieto stopky spolu s elektrónkovým VF generátorom, kde si tieto prístroje ukázal na konci videa a keď som včera na tvojich českých stránkach našiel článok o týchto stopkách, tak som nadobudol istotu že bude aj video a potešil som sa o to viac. Je to veľmi pekný prístroj s krásnym displejom, digitróny sú podľa mňa najkrajšie zobrazovače a hneď po nich sú fluorescenčné displeje. Ale som si vedomý aj jedného nedostatku tohto prístroja, je totiž taktovaný sieťovou frekvenciou (100 Hz po dvojcestnom usmernení) a sieťová frekvencia kolíše o desatiny percenta, pri hodinách to nevadí, lebo sieťová frekvencia je riadená tak, aby jej stredná hodnota vzhľadom k celému dňu bola čo najbližšie 50 Hz, lenže táto kompenzácia sa u stopiek neuplatní, lebo nebežia celý deň tak ako hodiny a tým pádom bude odchýľka nameranej hodnoty pomerne veľká v porovnaní so skutočnosťou, ale chápem že použili túto koncepciu z ekonomických dôvodov, lebo okrem toho, že by pre vyššiu presnosť museli použiť kryštál, tak by museli byť použité ďalšie deličky (MH7490), pri 100 kHz kryštáli by museli byť použité ďalšie tri kusy MH7490 a to by výslednú konštrukciu predražilo, lebo v tej dobe nebol ani kryštál ani TTL IO zrovna lacná záležitosť, takže toto riešenie do určitej miery chápem. Ďakujem ti za toto veľmi pekné video.

[RODALCO]

That is a very interesting Nixie timer. Interesting to see the 5490 decoder IC's instead of the more common 7490 IC's. The 5490 is the military version. The 74141 is the true Nixie driver. You have to be very careful to avoid shorting the 5V TTL voltage with one of the 150V DC Nixie Voltages. Nice to have a spare Tesla 74141 IC for repair. Nice FLIR camera you have as well.

[airmann]

Damn that was a high resolution shot of your cat lol. Cat me off guard

[TechGorilla]

I get nervous when it sounds like a creator has been sick for a while. I hope you're well my Czech friend.

[d.k.]

Nice little gadget.
Neat circuit.
I LOVE this kind of 3D effect in this nixie display.
The way the single digits seems to run from back to Front in a single tube.

[TheFicktion]

You have a lot things from Poland :) Pozdrowienia z Polski :)

[KeritechElectronics]

Lovely stopwatch, though it's mechanically FUBAR. The C bracket construction makes it very hard to access for servicing. Inice board, and it's very educating to see the thermal camera views.

BTW, I bought a modern DIN 8-pin connector yesterday with my Commodore 64 in mind. Tried plugging it in today and it didn't go despite the good pin layout. The pins turned out to be denser than the original (and probably the old Unitra Eltra DIN connectors would be good here). was I pissed! Watch out for those new production connectors.

[Soomaali_Mida]

Thanks bro, your videos are educational entertaining.

Let me say this ' DiodegoneCAT' 😂

[antibrevity]

Good job getting it to stop at 1.23.46. So close <g>.

[MuzZhor]

it's nice that you can fix things older than +- 40 years

je pekný ze dokazes opravit veci starší +- 40 let

[antibrevity]

Unless some sort of correction is being made on the grid, AC frequency should be quite accurate so not having a crystal simplifies the device and is a practical solution so long you don't move to a place with different line frequency ;) . This could be a good teaching tool for basic TTL logic.

[BDYT]

For a second i thought that remote connector was actually a PS2 Port ;-;

[piconano]

This stop watch didn't come with a wrist band?

[ancientlink]

Can you do more diy videos pls? Thanks

[Novus_Ordo_Conditor]

I wonder if it was used to calculate lap times in car races?

[cambridgemart]

I hadn't seen any Eastern Bloc hardware using TTL before, they usually used either Soviet designed and numbered devices, or used renumbered devices based on western parts.

[ValuedTeamMember]

This was a very "timely"" video. I'm glad I didn't miss a "second" of it. I left a note to myself to "watch" your next video on my kitchen "counter". ¯\_(ツ)_/¯