[neonixie-l] Re: Can anode current limiting be replaced with cathode current limiting?

[Robert L]

Individual cathode current limiters work great... Stole the idea from 
Greg's B7971 design. Note the transistors and current set resistors lining 
the display in the photo below. First light today on this Sperry SP-151 
Panaplex.

In this case, I'm using individual cathode limiting due to widely differing 
amounts of current needed by the various segments for uniform intensity... 
not to mention the impact of varying numbers of segments for different 
displayed values using basic anode limiting. Note the uniform glow? :-)

These are running a test with a single one and 31 zeros circulating at high 
rate around the 32 element shift register that drives the transistor bases. 




Will use the same design with a Telefunken ZM 1350 display that's also in 
the works. Same issues and concerns a the B7971.

Best regards,
Bob

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/33e234cc-8a01-4c03-9102-50f2c13efb91%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: PV Electronics R568 Clock Project With Black R|Z568M Nixie Tubes

[Edward Van Belkom]

> I got my acrylic cover today and had some picture on the final build. 
> Thanks everyone that helped with this project. It is my first time clock I 
> built but all the advice  got  me to this phase.
>

Thanks for all the help. I  am not good on photography so please excuse the 
pictures I posted but trying to get an idea how it looks.



 

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/c8e3fbd9-e86e-4d64-98e2-d0bb2073fa4e%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Can anode current limiting be replaced with cathode current limiting?

[gregebert]

No difference; current is current, and that is what determines how bright 
the glow will be. However, the circuits you posted are quite different. The 
anode-resistor provides current-limiting, but no current regulation: If the 
supply voltage or the tube's voltage drop change, so will the anode 
current. This can be undesirable, especially if it results in 
higher-than-spec anode current which can lead to premature failure.

The cathode circuit you showed will regulate the current, irrespective of 
the anode voltage or tube condition.

You can also use a similar regulation technique at the anode; you would use 
a PNP or PMOS (my preference) device.

I've used all of these techniques in my designs, and for the 7971 nixie 
clock I recently finished, I use *both* anode AND cathode current 
regulation.

If you are using plentiful and inexpensive tubes, such as IN-1's, IN-8's, 
an anode resistor is fine. But if you are going for larger tubes like 
IN-18, 7971, or Dalibor's I would definitely use a current regulator.

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/116f57d7-4be5-49bb-81d6-6d75aa3fe47a%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Can anode current limiting be replaced with cathode current limiting?

[David Forbes]

Allen,

This should work. It's not done because it uses more parts than does anode
current limiting.

My Nixie watch design uses a current limited power supply, which is a more
efficient way to do this, but only in a multiplexed design.


On Nov 11, 2017 2:38 PM, "Allen Dutra"  wrote:

Greetings Neonixie group,

Anode current limiting seems to be a fundamental design element when using
Nixie tubes. Yet is there anything fundamentally wrong with limiting
cathode current instead of anode current, assuming a design will reliably
turn on one cathode at a time?

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/CAPbqtvfpNnBDpufyd%2BPv7fi3KbEkmkHLTWvLv7P7A-qH2Audbg%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Can anode current limiting be replaced with cathode current limiting?

[Allen Dutra]

Greetings Neonixie group,

Anode current limiting seems to be a fundamental design element when using 
Nixie tubes. Yet is there anything fundamentally wrong with limiting 
cathode current instead of anode current, assuming a design will reliably 
turn on one cathode at a time?




If my math and understanding checks out, one should be able to accurately 
limit cathode current with a common collector transistor circuit and 
eliminate the anode resistor entirely. The circuit shown bellow controls 
current based on the equation: Ic = Ie = (Vb - Vbe)/Re





Controlling a Nixie this way should allow a designer to, eliminate the 
anode resistor, ignore the voltage drop of the Nixie tube, and not be 
concerned with the exact value of anode voltage. The only variables that 
really matter are base voltage (Vb), base-emitter voltage drop across the 
transistor (Vbe), and emitter resistance (Re). Control these three 
variables and Collector, Emitter and Nixie currents should all be limited 
to the same value. The only requirements for anode voltage being; anode 
voltage needs to be greater than the Nixie tube striking voltage, the 
collector emitter voltage rating of the transistor needs to be greater than 
the anode voltage and the transistor needs to dissipate the heat generated 
by the voltage drop. Overall, keeping anode voltage somewhat close to the 
Nixie tube striking voltage will improve efficiency. 

Are there any fundamental issues with the design direction I'm considering?

Thanks,

Allen Dutra



-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/3119acdc-bc1c-4cb5-9420-1f6aaf27962f%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: My first power supply!

[Paul Andrews]

There is no ripple that I can detect with my 'scope. As for saturation. I 
don't *think* so. I don't see any collapse in output voltage or surge in 
input current (would I? I don't know). The transformer is pretty capable, 
even though it is a little on the small side. I have got some potentially 
beefier transformers to try out.

I went for the regular 1oz, 2 layer board from OSHPark. I was wondering 
about the 2oz copper, but not sure if it would make any difference. I 
couldn't avoid a small ground loop with the 2-layer option, not sure if 
that makes any difference, but I wanted to stay away from 4 layers because 
ultimately I want to integrate it into a clock PCB and wanted to avoid the 
expense of 4 layers. I also avoided laying a ground plane under the 
transformer, but I wonder about leaving the ground plane there so I could 
use it as a thermal sink, but slap a bunch of vias in it to reduce 
(remove?) the eddy currents.

I'm pretty glad I went for surface mount everything. Way better selection 
of suitably spec'd components and of course it keeps it small :-)

On Saturday, November 11, 2017 at 2:00:24 AM UTC-5, Nick wrote:
>
> Nice job! - looks really well done. Might be interesting to see if you can 
> push the efficiency up a bit.
>
> Are you sure there's no core saturation going on, and what about output 
> ripple?
>
> Nick
>
>

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/6f62168f-4525-421d-af38-864fcd71d6ad%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Upside-down nixies

[newxito]

Nice tubes, thanks James. But I am looking for tubes with larger digits. I 
think I will apply plan B and use 6 x Z5660M with a 3D printed socket to 
hide the pins and put the cables behind the tube. I hope it looks then like 
a candle in the crystal ball.

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/07f1cab3-c53b-4b16-aca5-dbd552124229%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: threeneuron's Dekatron clock

[Jon]

On Friday, November 10, 2017 at 12:22:10 AM UTC, Phill Scanlon wrote:
>
>
> To summarise. The only pins which MUST be identified are the Anode, the 
> Guide and/or Guides.
>  
>

Well, all dekatrons do have at least one main cathode brought out to the 
base individually in addition to any commoned main cathodes and it is 
necessary to distinguish this one if you actually want to be able to count 
using the tube or know where the glow is. However if all you want to do is 
spin a tube continuously, then for most basic dekatron types I guess you're 
right. Identify the anode and guide(s), apply the appropriate inputs to 
those, ground the other pins as cathodes and it'll work. However the 
situation does get more complicated for tubes like GC10D, GS10H where some 
of the guide electrodes are brought out individually to the base. Get the 
hang of things on the basic tubes first and then you should find it easy to 
deal with the extra bells and whistles of those tubes.

 

> My understanding of the dekatron is that the index or K0 pin is NOT 
> connected to any other pins.
> The only reason I say this - as I have never taken one apart - is from 
> this gif file I have attached.
>
> Guessing that the gif is is over simplified.
>
> Correct ?
>

The GIF is spot on for a two-guide counter dekatron like GC10B or OG4. And 
yes, the index or K0 pin is not connected to anything else in that whole 
array of electrodes circling the anode, just the individual electrode as 
shown. Some manufacturers call this the 'output cathode'. In a selector 
dekatron like GS10C or A101, every one of those purple electrodes that are 
connected together in the GIF as K1-K9 (RTN) is not connected to anything 
else and brought out to its own pin on the base. In a computing counter 
like GC10/4B, some of those electrodes have their own pin on the base, the 
remainder are internally connected to make a common cathode array like in 
the GIF.

Your OG8 is therefore different to the GIF in 2 ways. First K3, K5 and K9 
don't connect internally to the common cathode line - they are just brought 
directly out to the base, exactly like K0 is shown here. Second, it has a 
single directional transfer electrode array instead of the two guide 
electrode arrays, so you need to imagine all the orange coloured pins and 
connections in the GIF as being absent.
 
Jon.

-- 
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 neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/b60b249f-966a-49ec-8261-6d34adb5cce7%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.