OG8 dekatrons

[Jon]

Anyone here had much experience with OG8 dekatrons? They're a high speed purple glow type with shaped cathodes and unidirectional (fast) counting, but require rather higher anode voltage than normal to operate. I've got a few of these, but on testing recently a large majority seem to be dead. The proportion seems to be rather higher than even known offenders such as the GC10D.

 

Just wondering if that's a common experience or I got unlucky?

 

Cheers,

 

Jon.

[threeneurons]

Personally, I'm leery of all high speeds. I still don't know if there's a consensus on what the gas mix is in those purple jobs. I'm leaning towards hydrogen. If so, it'll react with the innards, and eventually, no joy.

I haven't played with that tube, but I have looked at its datasheet, and its specs. Its similar to the OG-3, much in the same way that a GC10/4B is related to a GC10B, and a OG-9 is to an OG-4. In the OG-3, OG-4, GC10B, and 6482 only one cathode is brought out separately, while the others are ganged together. In the OG-8, OG-9, GC10/4B, & 6802, a few of the other cathodes are also brought out separately, using up the remainder of the octal base pins.

[dr pepper]

I've played with og3's, I thought they were part argon, I might be
wrong though.
The only drawback for me was that they need 3 microcontroller pins, or
some circuitry to provide the 3 phases to drive them.
The brightness of the glow is also a bit less than a neon tube.
I had trouble getting the reset to 0 working, and opted for 3 neurons
detect on 0 approach instead, the tube is a seconds pendulum and mode
function indicator for one of my clock projects.

[threeneurons]

| I've played with og3's, I thought they were part argon, I might be wrong though.

| The brightness of the glow is also a bit less than a neon tube. 

There are other gases that glow blue/violet. The only reason, I'm thinking its not argon, is that argon is a larger atom than neon. The color does correspond to energy transitions, with violet having the most energy, and red having the lowest. Orange is just a tad more energetic than red. How that translates to ionization speed, I have no clue. I tried looking at the emissions of these tubes with a cheap spectrometer, but still got multiple lines. It really needs to be done with a good quality calibrated spectrometer, and in absolute darkness. Still, a single element will have multiple lines, and it still may be a mix, of several gasses. I've also heard helium tossed around. That also glows blue, and has the bad habit of being able to leak right thru glass. That was a problem we had with HeNe lasers.

So other than the high dud rates of these tubes, the glow brightness, or lack of it, is a second strike against these tubes.

The 3rd guide doesn't really bother me. Especially, when stepped by a uC. That means 40 rods instead of 30, for finer resolution. That's why I like using Japanese DK23 dekatrons, with my "do-hickie" circuit. 40 rods, and it glows orange !

Nice to hear someone else having a dekatron pendulum, as part of their nixie clock. Jason Harper started it a long time ago, and I've used it on 4 of my own, but I haven't made a new clock in ages.

[dr pepper]

I havent bothered with a deka pend since, noone I've showed it likes
it, 'whats that thing doing'.
Personally I like the glow from a dekatron just as much as a nixie.
Next in line for build is a vfd, I have several russian jobs waiting
to be used.