Remote Driver Board Options

[Chachi88]

I am climbing stairs from the foot of the mountain to sit at the feet of all you nixie gurus.

What is the current state of the art for remote driver boards?  I am aware some of the older drivers are not as reliable or can cause the tubes to degrade quicker.  Some of the new options I am seeing have "cathode poisoning prevention"  I have recently come upon qty 6 of the NL8091's and their original sockets and socket mounting plate, which I wish to reuse for a clock. Are there any off the shelf boards even capable of driving this tube?  I was looking at a board on ebay that comes with an IR remote but it seems too good to be true, I would be willing to spend 5 times as much for a board that was properly documented and put together and had some sort of pedigree...

Thanks in advance for any advice or direction you can give.

[gregebert]

Those are very valuable tubes, so if you are willing to design your own driver and the PC board, I would do that. I've made several clocks and never had a design problem that affected the tubes. Even if you find a board to purchase, see if any of the following apply:

Some of my suggestions:

#1. I dont like sockets because they put stress on the tube pins. Some of them grip the pins very hard and it's difficult to insert or remove the tubes, which adds to the risk of bending or breaking the pins or putting stress on the glass. Instead, I use socket pins soldered into the PCB, and the force to insert/remove tubes is very low.

#2. Direct drive. There's no need to multiplex individual tubes, and there's no cost benefit when tubes are worth hundreds of dollars apiece and the drive electronics is at most a few dollars. Multiplexing requires higher current, and that degrades the tube's lifetime.

#3. Use a current regulator, and set the current at the recommended spec value; too high and you wear-out the tube. Too low and you risk cathode poisoning. A single anode resistor per-tube is OK, but as the anode voltage varies, so does the current (no such problem with a current regulator, though). You can mitigate this by using a higher anode supply voltage and larger anode resistor, at the expense of more wasted energy. As tubes age, their striking voltage may increase, so having a higher anode voltage will help mitigate this.

#4. PIR sensor. Turn off the tubes if nobody is there to watch them.

#5. Protect the tubes inside a case, and make sure there is enough ventilation so the heat doesn't build-up inside. On my later designs I have a thermal sensor (sometimes several) so that software can monitor critical temperatures and shutdown if things get too warm.

#6. Depoisoning routine to exercise all cathodes.

#7. Backlighting (or base lighting). I havn't done this on any of my clocks, and I've never had problems with tubes not firing-up. Others have reported problems without backlighting. It can have aesthetic value, though I'm not fond of it.

That should cover the necessities for the tubes; there are always lots of other features that can be done, especially if the clock has open-source software (or you develop it on your own).

[Peter Doroba]

This is the clock I made using Richard Scales B-8091 clock PCB.

https://www.facebook.com/groups/142414439207058/search/?q=b-8091

[Nicholas Stock]

Pete also has a remote driver system that will work with B8091s... 

https://www.pvelectronics.co.uk/index.php?main_page=index&cPath=43

Nick

Sent from my iPhone

On Sep 18, 2024, at 07:16, Peter Doroba <peter....@gmail.com> wrote:



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[Chachi88]

First off, thank you guys very much for your input here, I will address them most recent to oldest.

Peter,

I apologize I cannot view this link I do not use facebook.  I also cannot find a link to Richard Scales B-8091 clock PCB that you mention.

Nicholas Stock,

Thanks a lot for showing me this website, I had come across it also, but was discouraged by the "sold out" notification for this board.  Is there any way I can message the seller, you think?  I really like all the features this board has already implemented for me...but maybe greg's first comment is calling my name...

gregebert,

Thanks for the very informative points, I have addressed my responses and followup questions individually below in Italics.

#1. I dont like sockets because they put stress on the tube pins. Some of them grip the pins very hard and it's difficult to insert or remove the tubes, which adds to the risk of bending or breaking the pins or putting stress on the glass. Instead, I use socket pins soldered into the PCB, and the force to insert/remove tubes is very low.

Point taken, I will look at my sockets carefully before considering using them.  Otherwise I will probably borrow your idea, cheers.

#2. Direct drive. There's no need to multiplex individual tubes, and there's no cost benefit when tubes are worth hundreds of dollars apiece and the drive electronics is at most a few dollars. Multiplexing requires higher current, and that degrades the tube's lifetime.

This is what I have understood as well, thanks for confirming.

#3. Use a current regulator, and set the current at the recommended spec value; too high and you wear-out the tube. Too low and you risk cathode poisoning. A single anode resistor per-tube is OK, but as the anode voltage varies, so does the current (no such problem with a current regulator, though). You can mitigate this by using a higher anode supply voltage and larger anode resistor, at the expense of more wasted energy. As tubes age, their striking voltage may increase, so having a higher anode voltage will help mitigate this.

Understood, is this implemented a current regulator per tube or is this a single current regulator?  If single current regulator, how do you account for possibly having varying current with different digit activation? or am I missing an operating principle here?

#4. PIR sensor. Turn off the tubes if nobody is there to watch them.

This will definitely be part of the overall clock design (also incorporating a Noritake Itron 20 character 5x7 VFD).  I plan on having a smoked plexiglass case housing the electronics and VFD while mounting the nixie tubes on top. Which leads on to our next point...

#5. Protect the tubes inside a case, and make sure there is enough ventilation so the heat doesn't build-up inside. On my later designs I have a thermal sensor (sometimes several) so that software can monitor critical temperatures and shutdown if things get too warm.

If the tubes are always going to be high up in the air (on a dedicated wall shelf), is casing them necessary? Could not casing them cause convection heat to rise around them and risk stressing the glass?  The thermal sensor is a good idea, for the inside of my case I will certainly implement this, probably in multiple spots as you suggested.  Do people ever put thermocouples on the tubes themselves to monitor heat or could you see value in it?  I might consider that in my design.

#6. Depoisoning routine to exercise all cathodes.

This is not the first time I have read of depoisoning (a common feature on most bonafide driver boards I have seen). I have also seen there are different marketed techniques for depoisoning: slot machine, strobe, etc...

What are the principles behind cathode poisoning and the theory of prevention? If this has already been documented somewhere please give me strength on my journey you send me on.

#7. Backlighting (or base lighting). I havn't done this on any of my clocks, and I've never had problems with tubes not firing-up. Others have reported problems without backlighting. It can have aesthetic value, though I'm not fond of it.

I tend to agree with you, for me, this was considered aesthetically not necessary, but if there is value in ensuring operation, I will plan on incorporating this in the design even if it is left partially implemented in hardware or neglected in software...

That should cover the necessities for the tubes; there are always lots of other features that can be done, especially if the clock has open-source software (or you develop it on your own).

Thank you again sincerely for expounding this much on this, I in the end, I am hoping to find a clock/driver board with open source software or just raw signal input pins exposed that way I can incorporate it in with my VFD with minimal additional effort expounded on the nixie driver block (because it has already been done probably way better than I would do it on a first pass).  I can then address it, animate it, etc. with a microcontroller of my own...

[Nicholas Stock]

I contacted Pete, he has the boards available... send him an email if interested.

Cheers,

Nick

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/01b394f6-8ab8-46c6-9287-9ae661b0a6f2n%40googlegroups.com.

[gregebert]

#3. Use a current regulator, and set the current at the recommended spec value; too high and you wear-out the tube. Too low and you risk cathode poisoning. A single anode resistor per-tube is OK, but as the anode voltage varies, so does the current (no such problem with a current regulator, though). You can mitigate this by using a higher anode supply voltage and larger anode resistor, at the expense of more wasted energy. As tubes age, their striking voltage may increase, so having a higher anode voltage will help mitigate this.

Understood, is this implemented a current regulator per tube or is this a single current regulator?  If single current regulator, how do you account for possibly having varying current with different digit activation? or am I missing an operating principle here?

Single regulator per-tube, on the anode. Except for the RZ568m, I've only seen tubes spec the same current for each numeral. Generally I use an HV5530 to drive the cathodes, so only the anode-side can be current-regulated. I use a PMOS transistor with a resistor between source and the + anode supply, drain goes to the nixie-tube anode, and the gate goes to a trimpot to adjust the gate voltage (about 8 volts negative w/ respect to the anode supply). Assuming the Vgs(on) of the PMOS transistor is constant, the current is limited by the voltage-drop across the resistor.

With my B7971 clock, I have a current-regulator on the anode, as well as for each cathode because the datasheet sets different currents for the various segments. That works out to 128 current regulators for the 8-tube clock, but given the ridiculous cost of a replacement tube it's worth the expense.

#4. PIR sensor. Turn off the tubes if nobody is there to watch them.

This will definitely be part of the overall clock design (also incorporating a Noritake Itron 20 character 5x7 VFD).  I plan on having a smoked plexiglass case housing the electronics and VFD while mounting the nixie tubes on top. Which leads on to our next point...

Be sure the PIR sensor isn't covered by anything; even clear-plastic will block infrared.

#5. Protect the tubes inside a case, and make sure there is enough ventilation so the heat doesn't build-up inside. On my later designs I have a thermal sensor (sometimes several) so that software can monitor critical temperatures and shutdown if things get too warm.

If the tubes are always going to be high up in the air (on a dedicated wall shelf), is casing them necessary? Could not casing them cause convection heat to rise around them and risk stressing the glass?  The thermal sensor is a good idea, for the inside of my case I will certainly implement this, probably in multiple spots as you suggested.  Do people ever put thermocouples on the tubes themselves to monitor heat or could you see value in it?  I might consider that in my design.

You never know when some flying object might hit a tube. Putting holes in the bottom of the case and on the top (or on the back-side at the top) will usually get enough convection. I have 1 clock with a fan that can be turned-on by software if one of the thermal sensors is out-of-range, but it hasn't been triggering. Nixies dont get hot, but power transformers and heatsinks can so I JB-weld an I2C thermal sensor on the critical ones and have software monitor the temperature, and shutdown or turn-on a fan if needed. If you have a DS3231, it has a built-in thermal sensor. I also have one in the Raspberry Pi CPU. The rest are on an I2C chain.

#6. Depoisoning routine to exercise all cathodes.

This is not the first time I have read of depoisoning (a common feature on most bonafide driver boards I have seen). I have also seen there are different marketed techniques for depoisoning: slot machine, strobe, etc...

What are the principles behind cathode poisoning and the theory of prevention? If this has already been documented somewhere please give me strength on my journey you send me on.

Basically, unused cathodes can accumulate debris over time if they are not used, ie they get poisoned. My IN-18 clock cycles digits thru their unused numerals for 1 hour per night. Tubes that glow 0-9 evenly, such as the units-seconds and unit minutes, are simply shutoff for depoisoning. Others that go 0-5 all day are cycled 6-9. Lastly, the ones that are static (day, month, year) are cycled 0-9.

My B7971 clock does a segment walk whenever it's not displaying the time (no PIR activity). Each segment (15 per tube) runs about 200msec, then repeats that on each of the 8 tubes sequentially. It works out to about a 1% duty cycle.

[Richard Scales]

I think I have some info at nixology.uk under the PRISM-18 project page.

Full NTP Sync (clock needs wifi), web gui, pir activation, 
etc/etc/

PM me for any more info.

 - Richard

[Chachi88]

Richard,

Thanks I will PM

gregebert,

Funny you should mention the B7971, in this lot with the NL8091s I also received an armload of these tubes (they actually have the same socket), funnily enough...  You wouldn't happen to have a FLW clock design using your circuitry available? That will be next on my hit-list and I will need kits to make 3 clocks (one will be a gift to the person who gave me all these tubes).

Thanks so much for your help, folks.

[Nicholas Stock]

There's always the MOD_6 in case you're not familiar with it... I believe Michael may have some left?

http://badnixie.com/Badnixie.com_Welcome.html

@Michael Barile ?

Cheers,

Nick

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/24034a0a-3836-4449-9693-1eb861b77570n%40googlegroups.com.

[MichaelB]

I do. Still 5 or so in stock. Thanks Nick

[Chachi88]

I don't think I have enough tubes to do 3 6-tube clocks.  I am also noticing that all the FLW circuits and boards I am finding seem to be multiplex drive, which is undesirable from what we have discussed...but I would love to be proven wrong.  If not, there might be an opportunity here...

Thanks again y'all.

[Nicholas Stock]

https://www.thomasnixie.com/the-gps-flw-nixie-clock

Still available without tubes etc if you're interested...

Nick

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[Chachi88]

Nick,

This design uses a multiplex scheme, which as discussed is considered undesirable as it impacts tube life.  I have seen this design but am looking for a direct drive alternative.  I am seeing that there is a "smartsocket" that supports this tube...interesting.

Thanks

[Nicholas Stock]

Understood. However (and this has been a discussion many many times on this forum), I think multiplexing gets too much hate. I've had multiplexed (IN14) clocks that are still going strong over 10 years now with no noticeable deterioration in the tube, so my opinion differs from some, in fact you will find specific multiplexing details in some nixie tube datasheets (Burroughs wrote an application note on just this topic - https://neonkev.com/wp-content/uploads/2020/10/n101.pdf). I understand all the comments about increased current for similar brightness etc and how that may impact tube life, especially when dealing with tubes that are becoming rarer and rarer, but it may be a bit overly cautious?

... bracing for the can of worms this may unleash on the forum.... :)

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[MichaelB]

I agree with Nick in that I have at lease 6 Muxed clocks that have been running for years on end without incident. And I  have 2 of Jeff’s/Pete Hands FLW clocks that have been running for years as well. BUT, the fact remains a direct drive clock will produce a brighter tube. So, if thats a concern, a direct drive design might be preferable. AND if you have 6) 7971’s looking for a home, we still have Lumina Kits available! You will need to build you own case. http://www.badnixie.com/Badnixie.com_Welcome.html

[gregebert]

>gregebert,

>Funny you should mention the B7971, in this lot with the NL8091s I also received an armload of these tubes (they actually have the same socket), funnily enough...  You wouldn't happen to have a FLW >clock design using your circuitry available? That will be next on my hit-list and I will need kits to make 3 clocks (one will be a gift to the person who gave me all these tubes).

Ping me offline if you are interested. It's not in user-friendly kit-mode, and it does require some RasPi/Linux skills to connect it to your WiFi network to get the time. You might want to consider the MOD6 / Lumina design, especially if you are making clocks for others. I do my own designs because I like the challenge and the ability to choose the features, etc.