Re: [neonixie-l] VFD filament drive

['John Rehwinkel' via neonixie-l]

> I wonder why there should be no air gap?

Air gaps lower the inductance, but stabilize it and store energy in the gap.  
Working forward from this, you generally find flyback type circuits use gapped 
cores, and others generally instead opt for best coupling and highest 
inductance.

- John

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Re: [neonixie-l] Newbie would like to introduce himself

[Bill Notfaded]

Wow Rich I have some panaplex and devices with them but the model you 
mention is rarer it seems.  I wonder if they were used in some arcade games 
as I found a picture 
here:  https://www.andysarcade.net/store2/images/source/comp/disp05.JPG
You can see the common for digits on the right and one on the left.

Bill

On Friday, August 20, 2021 at 11:55:47 AM UTC-7 nice...@optonline.net wrote:

> Hi Bill,
>
> Thanks for the welcome! Yes, I agree with you about the “sickness” and I’m 
> probably not getting any better!
> It’s bad enough trying to find parts that are generally considered 
> unobtainium, but you bring up another point
> when trying to find a manual (either owner or service) that may be harder 
> to locate than the parts themselves.
> One example of that is my search for Sperry Panaplex display SP-737. This 
> 3-digit bugger has one anode for
> the left digit and another common to the other two digits. This is used in 
> a Marlin calculator for the two least-significant
> digits as well as polarity and error indicator. Sooner or later it will 
> probably appear for sale at a price equal to an
> ounce of gold! Such a deal! All the best.
>
> Rich N.
>
>   
>
> On Aug 20, 2021, at 12:20 PM, Bill Notfaded  wrote:
>
> Welcome Rich... I too collect nixie tube test equipment including 
> calculators, frequency counters, scalers with dekatrons, and nixie 
> voltmeters.  I even have some X,Y machining displays.  I've been wanting to 
> take some time to document some them.  Once I get a piece of classic 
> display technology gear then I'm always looking for the original manuals to 
> go with them as well!  It's kinda a sickness.
>
> Bill
> On Thursday, August 5, 2021 at 7:15:26 PM UTC-7 Pramanicin wrote:
>
>> Welcome to the madhouse! Only kiddinglots of very knowledgeable and 
>> more importantly, friendly and helpful folks on this list. No such thing as 
>> a stupid question here (unless you ask the same one twice. ha ha).
>>
>> Cheers,
>>
>> Nick
>>
>> On Thu, Aug 5, 2021 at 3:34 PM gregebert  wrote:
>>
>>> "Abandon all hope ye who enter here"...it's too late to turn back; 
>>> nixie tubes are not only addictive, but they are known to cause other 
>>> addictions.
>>>
>>> On Thursday, August 5, 2021 at 6:57:47 AM UTC-7 Keith Moore wrote:
>>>
 Welcome! This place is my fave read of the day each day! :-) 

 On Wednesday, August 4, 2021 at 5:21:59 PM UTC-4 Terry Bowman wrote:

> On Aug 4, 2021, at 2:39 PM, Richard Nicewonger  
> wrote:
>
> My particular interest is not necessarily clocks (although I do have a 
> nixie version) but more toward calculators and test equipment using these 
> type of displays. I am always a sucker for more of these that may require 
> some work to be operational. Sometimes I shoot myself in the foot because 
> of the difficulty in finding replacement parts for 50+ year old 
> equipment, 
> especially displays!
>
>
> You're in good company. The cost of replacement tubes is rising at an 
> increasingly non-linear rate. Service manuals range from free pdfs to 
> over-priced eBay listings to non-existent.
>
> As for other parts, there are those lighted push-buttons on my 
> Systron-Donner Time Code Generator/Reader. My apologies for complaining 
> about this at least three times before but the d*mn thing is working 
> perfectly and all it needs is a fix for those broken caps!
>
>
> I hope to get some insight from knowledgeable folks here. So, looking 
> forward to having some interesting and useful conversations.
>
>
> You came to the right place. I shot myself in the foot by not joining 
> up a year earlier.
>
>
> Terry Bowman, KA4HJH
> "The Mac Doctor"
>
> https://www.astarcloseup.com
>
> “...the book said something astonishing, a very big thought. The 
> stars, it said, were suns but very far away. The Sun was a star but close 
> up.”—Carl Sagan, "The Backbone Of Night", *Cosmos*, 1980
>
>
>
>>> -- 
>>> You received this message because you are subscribed to the Google 
>>> Groups "neonixie-l" group.
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>>> an email to neonixie-l+...@googlegroups.com.
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>>> https://groups.google.com/d/msgid/neonixie-l/cfef22e6-3f18-4eb7-88c3-081c03576cc6n%40googlegroups.com
>>>  
>>> 
>>> .
>>>
>>
> -- 
>
> You received this message because you are subscribed to a topic in the 
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> To unsubscribe from this group and all its topics, send an email to 
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> To view this discussion on the 

Re: [neonixie-l] VFD filament drive

[David Pye]

For mine I used one of those cheap eBay buck converters. 5v in, 1.x v out
(adjustable). 8 iv11 tubes, running for a few years without a blip.

If you needed AC, you could always just use an H bridge and a
microcontroller pin to flip it at a suitable frequency with a smoothing cap.

I found I couldn't have ordered the components cheaper than the finished
eBay module...

David

On Wed, 1 Sep 2021, 14:57 Dekatron42,  wrote:

> You can use airgaps in transformers in some cases but this design should
> be without one according to Ed.
>
> I am using ferrite pot cores in some other designs where they are wound as
> a transformer but where the Q-value is of importance and there I use an
> airgap and also a trimmer through the center to adjust them for a minimum
> Q-value at a certain frequency.
>
> Q-value according to TDK:
> https://product.tdk.com/en/contact/faq/inductors-0003.html and also at
> Wikipedia: https://en.wikipedia.org/wiki/Q_factor
>
> This article explains airgap in inductors/transformers somewhat:
> https://www.linkedin.com/pulse/why-do-we-provide-air-gap-usually-inductor-designs-transformer-p
>
> So sometimes it is a choice depending on design criteria like Q-value and
> material used in the transformer. There are normal laminated transformers
> that use an airgap too, but most mains transformers do not.
>
> /Martin
>
>
>
> On Wednesday, 1 September 2021 at 15:11:31 UTC+2 Paul Andrews wrote:
>
>> Martin,
>>
>> I wonder why there should be no air gap?
>>
>> - Paul
>>
>> On Wednesday, September 1, 2021 at 1:55:30 AM UTC-4 Dekatron42 wrote:
>>
>>> Paul,
>>>
>>> I'll ask him, but a quick search at Digikey showed both some RM10 and
>>> ETD29 cores, but only a few. Finding Ferrite cores today is not easy, I
>>> have searched some for other projects and they aren't usually stocked in
>>> the ranges that the manufacturers make them, and if you want something
>>> outside what is available in stock it becomes very expensive as you'll have
>>> to by thousands if not more. I usually try the ones they have and have to
>>> live with that since I can't buy the thousands needed to get the perfect
>>> one. I'll ask Ed to have a look and see if any of the ones that are stocked
>>> will do - just remember that they will have to be the transformer type
>>> without an airgap between the center pieces to work in this application.
>>>
>>> /Martin
>>>
>>> On Wednesday, 1 September 2021 at 04:26:30 UTC+2 Paul Andrews wrote:
>>>

 Hi Martin

 I tried to find a suitable core at digikey, but their parameters don’t
 map very well to the equation that Ed gives. Could he take a look at what
 they have and perhaps recommend something. For simplicity’s sake I just
 looked at toroids
 https://www.digikey.com/en/products/filter/ferrite-cores/936?s=N4IgTCBcDaICoHsBOCCWATAhgGwAQGNkBTAZxAF0BfIA

 Thanks - Paul
 On Friday, August 27, 2021 at 8:45:56 AM UTC-4 Dekatron42 wrote:

> Since transformers isn't my best area, I only have basic understanding
> of the intricacies but I have experimented some with different 
> transformers
> in different cases like when driving Trochotrons and Dekatrons I decided 
> to
> ask an acquaintance who has worked with transformers. His name is Ed
> Dinning, I got to know him over at the UKVRRR forum (UK Vintage Radio
> Repair and Restoration forum: https://www.vintage-radio.net/forum/),
> he told me you are welcome to contact him via me so that his email is
> somewhat protected - if you ask him anything related to the
> VFD-drivers it would be kind if you could post something here in this 
> forum
> so we all can learn from it.
>
> This is his answer to my question on what transformer to chose for the
> driver in the article, it sure helped me and I hope it helps anyone who
> wants to experiment with this driver:
>
> "Hi Martin, as it operates about 50/100KHz virtually any ferrite
> should do. It should be a transformer type with no air gap.
> The turns are normally based on the transformer equation for square
> waves
>
> N= V/ 4 * F * B* Ae
>
> N=turns, V=volts F=frequency,B= flux density, typically 200/250mT for
> a ferrite, Ae the centre pole area in M^2
>
> The actual losses come out later on in the design process and are not
> part of the initial criteria
>
> Copper sizing is normally based on 3A per mm^2 of cross sectional area
>
> The turns figure he gives looks about right for something like an RM10
> core, or you could try an EE25 or an ETD29 core in sat F44 materials
> ETD's are the core of choice for this type of application and should
> be readily available.
>
> The more turns that are used the lower the iron losses and the cooler
> the core runs, but the copper losses increase unless fatter copper is 
> used.
> Skin effect will be of minor importance at your frequency
>

Re: [neonixie-l] VFD filament drive

[Dekatron42]

You can use airgaps in transformers in some cases but this design should be 
without one according to Ed.

I am using ferrite pot cores in some other designs where they are wound as 
a transformer but where the Q-value is of importance and there I use an 
airgap and also a trimmer through the center to adjust them for a minimum 
Q-value at a certain frequency.

Q-value according to TDK: 
https://product.tdk.com/en/contact/faq/inductors-0003.html and also at 
Wikipedia: https://en.wikipedia.org/wiki/Q_factor

This article explains airgap in inductors/transformers somewhat: 
https://www.linkedin.com/pulse/why-do-we-provide-air-gap-usually-inductor-designs-transformer-p

So sometimes it is a choice depending on design criteria like Q-value and 
material used in the transformer. There are normal laminated transformers 
that use an airgap too, but most mains transformers do not.

/Martin



On Wednesday, 1 September 2021 at 15:11:31 UTC+2 Paul Andrews wrote:

> Martin,
>
> I wonder why there should be no air gap?
>
> - Paul
>
> On Wednesday, September 1, 2021 at 1:55:30 AM UTC-4 Dekatron42 wrote:
>
>> Paul,
>>
>> I'll ask him, but a quick search at Digikey showed both some RM10 and 
>> ETD29 cores, but only a few. Finding Ferrite cores today is not easy, I 
>> have searched some for other projects and they aren't usually stocked in 
>> the ranges that the manufacturers make them, and if you want something 
>> outside what is available in stock it becomes very expensive as you'll have 
>> to by thousands if not more. I usually try the ones they have and have to 
>> live with that since I can't buy the thousands needed to get the perfect 
>> one. I'll ask Ed to have a look and see if any of the ones that are stocked 
>> will do - just remember that they will have to be the transformer type 
>> without an airgap between the center pieces to work in this application.
>>
>> /Martin
>>
>> On Wednesday, 1 September 2021 at 04:26:30 UTC+2 Paul Andrews wrote:
>>
>>>
>>> Hi Martin
>>>
>>> I tried to find a suitable core at digikey, but their parameters don’t 
>>> map very well to the equation that Ed gives. Could he take a look at what 
>>> they have and perhaps recommend something. For simplicity’s sake I just 
>>> looked at toroids 
>>> https://www.digikey.com/en/products/filter/ferrite-cores/936?s=N4IgTCBcDaICoHsBOCCWATAhgGwAQGNkBTAZxAF0BfIA
>>>
>>> Thanks - Paul
>>> On Friday, August 27, 2021 at 8:45:56 AM UTC-4 Dekatron42 wrote:
>>>
 Since transformers isn't my best area, I only have basic understanding 
 of the intricacies but I have experimented some with different 
 transformers 
 in different cases like when driving Trochotrons and Dekatrons I decided 
 to 
 ask an acquaintance who has worked with transformers. His name is Ed 
 Dinning, I got to know him over at the UKVRRR forum (UK Vintage Radio 
 Repair and Restoration forum: https://www.vintage-radio.net/forum/), 
 he told me you are welcome to contact him via me so that his email is 
 somewhat protected - if you ask him anything related to the 
 VFD-drivers it would be kind if you could post something here in this 
 forum 
 so we all can learn from it.

 This is his answer to my question on what transformer to chose for the 
 driver in the article, it sure helped me and I hope it helps anyone who 
 wants to experiment with this driver:

 "Hi Martin, as it operates about 50/100KHz virtually any ferrite should 
 do. It should be a transformer type with no air gap.
 The turns are normally based on the transformer equation for square 
 waves

 N= V/ 4 * F * B* Ae

 N=turns, V=volts F=frequency,B= flux density, typically 200/250mT for a 
 ferrite, Ae the centre pole area in M^2

 The actual losses come out later on in the design process and are not 
 part of the initial criteria

 Copper sizing is normally based on 3A per mm^2 of cross sectional area

 The turns figure he gives looks about right for something like an RM10 
 core, or you could try an EE25 or an ETD29 core in sat F44 materials 
 ETD's are the core of choice for this type of application and should be 
 readily available.

 The more turns that are used the lower the iron losses and the cooler 
 the core runs, but the copper losses increase unless fatter copper is used.
 Skin effect will be of minor importance at your frequency

 It would also work on a normal laminated core at 50Hz which should not 
 be too big as you can run that at up to 1.5T flux density.
 Regulation could be a normal type of regulator set for constant current.

 Always many choices in Engineering

 Cheers,  Ed

 Ed Dinning Retired Engineer"

 /Martin

 On Wednesday, 25 August 2021 at 23:02:48 UTC+2 Paul Andrews wrote:

> When I have time, I will try the driver at the link Martin gave (
> 

Re: [neonixie-l] VFD filament drive

[Paul Andrews]

Martin,

I wonder why there should be no air gap?

- Paul

On Wednesday, September 1, 2021 at 1:55:30 AM UTC-4 Dekatron42 wrote:

> Paul,
>
> I'll ask him, but a quick search at Digikey showed both some RM10 and 
> ETD29 cores, but only a few. Finding Ferrite cores today is not easy, I 
> have searched some for other projects and they aren't usually stocked in 
> the ranges that the manufacturers make them, and if you want something 
> outside what is available in stock it becomes very expensive as you'll have 
> to by thousands if not more. I usually try the ones they have and have to 
> live with that since I can't buy the thousands needed to get the perfect 
> one. I'll ask Ed to have a look and see if any of the ones that are stocked 
> will do - just remember that they will have to be the transformer type 
> without an airgap between the center pieces to work in this application.
>
> /Martin
>
> On Wednesday, 1 September 2021 at 04:26:30 UTC+2 Paul Andrews wrote:
>
>>
>> Hi Martin
>>
>> I tried to find a suitable core at digikey, but their parameters don’t 
>> map very well to the equation that Ed gives. Could he take a look at what 
>> they have and perhaps recommend something. For simplicity’s sake I just 
>> looked at toroids 
>> https://www.digikey.com/en/products/filter/ferrite-cores/936?s=N4IgTCBcDaICoHsBOCCWATAhgGwAQGNkBTAZxAF0BfIA
>>
>> Thanks - Paul
>> On Friday, August 27, 2021 at 8:45:56 AM UTC-4 Dekatron42 wrote:
>>
>>> Since transformers isn't my best area, I only have basic understanding 
>>> of the intricacies but I have experimented some with different transformers 
>>> in different cases like when driving Trochotrons and Dekatrons I decided to 
>>> ask an acquaintance who has worked with transformers. His name is Ed 
>>> Dinning, I got to know him over at the UKVRRR forum (UK Vintage Radio 
>>> Repair and Restoration forum: https://www.vintage-radio.net/forum/), he 
>>> told me you are welcome to contact him via me so that his email is somewhat 
>>> protected - if you ask him anything related to the VFD-drivers it would 
>>> be kind if you could post something here in this forum so we all can learn 
>>> from it.
>>>
>>> This is his answer to my question on what transformer to chose for the 
>>> driver in the article, it sure helped me and I hope it helps anyone who 
>>> wants to experiment with this driver:
>>>
>>> "Hi Martin, as it operates about 50/100KHz virtually any ferrite should 
>>> do. It should be a transformer type with no air gap.
>>> The turns are normally based on the transformer equation for square waves
>>>
>>> N= V/ 4 * F * B* Ae
>>>
>>> N=turns, V=volts F=frequency,B= flux density, typically 200/250mT for a 
>>> ferrite, Ae the centre pole area in M^2
>>>
>>> The actual losses come out later on in the design process and are not 
>>> part of the initial criteria
>>>
>>> Copper sizing is normally based on 3A per mm^2 of cross sectional area
>>>
>>> The turns figure he gives looks about right for something like an RM10 
>>> core, or you could try an EE25 or an ETD29 core in sat F44 materials 
>>> ETD's are the core of choice for this type of application and should be 
>>> readily available.
>>>
>>> The more turns that are used the lower the iron losses and the cooler 
>>> the core runs, but the copper losses increase unless fatter copper is used.
>>> Skin effect will be of minor importance at your frequency
>>>
>>> It would also work on a normal laminated core at 50Hz which should not 
>>> be too big as you can run that at up to 1.5T flux density.
>>> Regulation could be a normal type of regulator set for constant current.
>>>
>>> Always many choices in Engineering
>>>
>>> Cheers,  Ed
>>>
>>> Ed Dinning Retired Engineer"
>>>
>>> /Martin
>>>
>>> On Wednesday, 25 August 2021 at 23:02:48 UTC+2 Paul Andrews wrote:
>>>
 When I have time, I will try the driver at the link Martin gave (
 http://www.nutsvolts.com/media-files/Forum-Articles/QA_201110.pdf), 
 but without the transformer initially. As far as I can tell, the 
 transformer is just to make the VFD drive isolated so you can pull it up 
 above ground.

>>>

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