Multiplexing... or not?

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9 years 5 months ago #2454 by SuperNova
What are the benefits of not multiplexing?

Will i be able to power all 6 tubes?

What is the limit on multiplexing? One K155ID1 driver for 6 tubes, will the tubes have time to warmup and stay lit for long enough?

Heard 20ms minimum.

Project Military Issue Nixie Display: LINK

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9 years 5 months ago #2455 by Jeff
Replied by Jeff on topic Re: Multiplexing... or not?

SuperNova wrote: What are the benefits of not multiplexing?

Will i be able to power all 6 tubes?

What is the limit on multiplexing? One K155ID1 driver for 6 tubes, will the tubes have time to warmup and stay lit for long enough?

Heard 20ms minimum.


With regard to multiplexing, the benefits are:

(1) Fewer components.

(2) They strike well in cooler temperatures because of the higher cathode current necessary.

(3) Fewer instances of partial digit illumination because of the higher cathode current necessary.


The Disadvantages are:

(1) Profoundly Dimmer than direct drive.

(2) Flicker, or visual persistence. Very annoying.

(3) Audible noise if anode mux frequency is not high enough. Usually only a problem with 25mm or larger cathodes.

(4) Careful design to ensure anode or cathode "ghosting" is eliminated.

(5) Consumes more power than direct drive, usually 2x.

(6) Can't use Russian Prison labor made K155ID1.

Your power supply choice depends entirely on your tube choice.
The smaller tubes average between 1.5-2.0ma cathode current in direct drive. The larger tubes can consume up to 4ma cathode current. Of course you would scale your power supply design x7 tubes, with the extra for overhead safety or colon indicators.

Nixie Tubes don't typically require a warmup, as long as adequate cathode current is applied to the digit. Too low cathode current and you have full cathode digit illumination problems, as well as eventual cathode poisoning occurring on the less active cathodes or cathodes with a greater surface area. The "8" is an example of this problem.

If you are planning on using a microprocessor versus discrete logic, then I highly recommend any of the Supertex high voltage shift registers; HV5522, 5530, etc.

Hope this helps.
Regards, Jeff
The following user(s) said Thank You: Stuckey, SuperNova

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9 years 5 months ago - 9 years 5 months ago #2456 by SuperNova
Hello,

Would you recommend I multiplex since it is my first design/build?

All i am worried about is the brightness.

On another note, could you recommend a tube with rounded top? A bit like the IN-18 but not that expensive?

Thanks a lot for the help you provided.

EDIT: Considering building this PSU: LINK

Project Military Issue Nixie Display: LINK
Last edit: 9 years 5 months ago by SuperNova.

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9 years 5 months ago #2457 by Jeff
Replied by Jeff on topic Re: Multiplexing... or not?

SuperNova wrote: Hello,

Would you recommend I multiplex since it is my first design/build?

All i am worried about is the brightness.

On another note, could you recommend a tube with rounded top? A bit like the IN-18 but not that expensive?

Thanks a lot for the help you provided.

EDIT: Considering building this PSU: LINK


HI, I really don't want to influence your decision.
I pointed out the pros and cons, and will let you decide.

I don't know of any alternatives to the IN-18 that offer those similarities without actually costing more.

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9 years 5 months ago #2460 by SuperNova
Thanks for those advice.

What do you think about the PSU?

A quick P=IV -> (2*10-3)*170=0.34watts

For 6 tubes that would makes 2.4watts if they all run together.

Will it hold? Thank you for your time.

Project Military Issue Nixie Display: LINK

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9 years 5 months ago #2473 by neonglass
Your item 6 has me puzzled. I use that chip in multiplexed displays all the time.

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