It looks like you are using PWM dimming. Can you disable it for now, and 
then focus on optimizing dead-time between cathodes and the anode timing.

I'm fairly certain you want to turn OFF the anode before changing the 
cathode signals, allowing some dead-time, then turning on the next anode. I 
cant tell from the waveforms above if there is any dead-time or 
overlap/underlap.

On Thursday, January 7, 2021 at 11:05:27 AM UTC-8 Bill van Dijk wrote:

> This is a 1x4 multiplex, each tube is lit 25% of the time if no “dead 
> space” is built in the software. I have not checked the data sheets, but it 
> looks strange that the 0 output from the 74141goes to the 1 of the tube, 
> and so on. Anyway, with your problem, program a space between switching 
> digits, length to be experimentally done since different tubes switch 
> faster than others. The other thing to try is a resistor of a few hundred K 
> between the tube anode and ground to dissipate the space charge in the tube 
> quicker. (not sure if that works; I have not tried that myself). Generally 
> speaking it is not recommended to multiplex Nixies, it surely dims them.
>
>  
>
> *From:* [email protected] [mailto:[email protected]] *On 
> Behalf Of *Mateusz Dziuba
> *Sent:* Thursday, January 07, 2021 1:27 PM
> *To:* neonixie-l <[email protected]>
> *Subject:* Re: [neonixie-l] IN-4 ghosting, once again.
>
>  
>
> I did not develop specific circuit diagram for my clock, but it is build 
> around this project: (please don't mind wrong polarity of opto. Someone 
> draw it wrong.)
> [image: e44b2492e18895184e259a89f71556fc.jpg]
>
> czwartek, 7 stycznia 2021 o 18:32:35 UTC+1 Bill van Dijk napisał(a):
>
> Can you post the schematic? First I notice that a bright 1 has a ghost 2, 
> and it seems every number has a ghosted lower number. Could be timing 
> (discussed many times), or perhaps the KD1551s are too slow depending on 
> your multiplex speed. What is you multiplex sequence, i.e. 2x3, 3x2, 1x6 ?
>
>  
>
> Bill
>
>  
>
> *From:* [email protected] [mailto:[email protected]] *On 
> Behalf Of *Mateusz Dziuba
> *Sent:* Thursday, January 07, 2021 12:21 PM
> *To:* neonixie-l <[email protected]>
> *Subject:* [neonixie-l] IN-4 ghosting, once again.
>
>  
>
> Hi all,
>
>  
>
> I am working on nixie clock and experiencing ghosting between neighboring 
> tubes. Please see attached photo.
>
>  
>
> [image: 1.jpg]
>
>  
>
> I am using 6xIN-4 nixies, Arduino with Atmega328, 6xTLP627 transoptor for 
> driving anodes and K155ID1 chip for driving cathodes. I am multiplexing 
> nixies in interrupt. Code attached.
>
>  
>
> What i tried so far:
>
> 1. I connected 10x 1N4148 fast switching diodes from cathodes bonding 
> points to mid voltage of 90V. It didn't help a bit and increased power 
> consumption only.
>
> 2. I removed the diodes and tried "center-pull" all anodes and cathodes 
> bonding points through 500k ohm resistors. Didn't help, although reduced 
> decay of anodes after switching off.
>
>  
>
> Some photos below:
>
> [image: 4.jpg]
>
> [image: 5.jpg][image: 2.jpg][image: 3.jpg]
>
>  
>
> What comes to my mind, I might try to increase/rewrite blanking interval 
> but i am not sure how to do it inside interrupt. Maybe I should rewrite it 
> to the main loop.
>
>  
>
> All help, comments, suggestions are welcome. 
>
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