Re: [neonixie-l] USB connector shield

[newxito]

Thanks a lot for the information! There seems to be a lot of room for 
improvement for rev 2…
The PCB should arrive this week, I will make some tests before connecting 
this thing to the pc.


SWISSNIXIE - Jonathan F. schrieb am Dienstag, 16. Februar 2021 um 23:30:28 
UTC+1:

> First of all, grounding - or - how to connect the shield, is not really 
> specified, and usually you should consider the chip's datasheet / 
> application notes on how to do it. 
>
> For example, see the TUSB4020BI  
> Datasheet,
>  
> page 27/28. But surely this is for series production and professional 
> product, if used as hobbyist project, i would just connect the shield to 
> ground.
>
> A few more notes on USB:
>
> I would move away the usb connector as far as possible from the HV supply. 
> I guess U3 is the MCU, so place near there. Also make sure you put TVS 
> diodes on the Data lines, to protect them from ESD damage, and differential 
> routing maybe should be used here too. If you don't have a pcb tool that 
> can do this, try at leas to have the usb datalines in the same distance and 
> trackwith and route them as parallel as possible. 
> Maybe also try and measure power first, i've had some issues with running 
> a nixie circuit off a *Standart USB Computer Port* since those are 
> usually limited to 500mA. Newer computers have electronic fuses / 
> controllers, and i've had the issue that at the start, the psu spiked to 
> over 500mA, and the Computer turned the USB off.  USB3 ports usually have 
> 1000mA
>
> On Monday, 8 February 2021 at 21:58:02 UTC+1 newxito wrote:
>
>> The PC should see the board as a COMx connected over USB, so the software 
>> (C#/.NET) just has to send some WMI data (CPU load %, Disk usage %, …) to 
>> the serial interface… sounds easy :-)
>> The software should be a service, so the data can be sent even when 
>> nobody is logged in.
>> And I would like to shutdown the high voltage if the pc goes to sleep or 
>> turns off.
>> Probably I will end up killing my pc mainboard :-)
>>
>> Kevin A. schrieb am Montag, 8. Februar 2021 um 21:21:00 UTC+1:
>>
>>> Never underestimate firmware ;)
>>>
>>>

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Re: [neonixie-l] USB connector shield

[SWISSNIXIE - Jonathan F.]

First of all, grounding - or - how to connect the shield, is not really 
specified, and usually you should consider the chip's datasheet / 
application notes on how to do it. 

For example, see the TUSB4020BI  
Datasheet,
 
page 27/28. But surely this is for series production and professional 
product, if used as hobbyist project, i would just connect the shield to 
ground.

A few more notes on USB:

I would move away the usb connector as far as possible from the HV supply. 
I guess U3 is the MCU, so place near there. Also make sure you put TVS 
diodes on the Data lines, to protect them from ESD damage, and differential 
routing maybe should be used here too. If you don't have a pcb tool that 
can do this, try at leas to have the usb datalines in the same distance and 
trackwith and route them as parallel as possible. 
Maybe also try and measure power first, i've had some issues with running a 
nixie circuit off a *Standart USB Computer Port* since those are usually 
limited to 500mA. Newer computers have electronic fuses / controllers, and 
i've had the issue that at the start, the psu spiked to over 500mA, and the 
Computer turned the USB off.  USB3 ports usually have 1000mA

On Monday, 8 February 2021 at 21:58:02 UTC+1 newxito wrote:

> The PC should see the board as a COMx connected over USB, so the software 
> (C#/.NET) just has to send some WMI data (CPU load %, Disk usage %, …) to 
> the serial interface… sounds easy :-)
> The software should be a service, so the data can be sent even when nobody 
> is logged in.
> And I would like to shutdown the high voltage if the pc goes to sleep or 
> turns off.
> Probably I will end up killing my pc mainboard :-)
>
> Kevin A. schrieb am Montag, 8. Februar 2021 um 21:21:00 UTC+1:
>
>> Never underestimate firmware ;)
>>
>>

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Re: [neonixie-l] Re: Russian crt - foiled by plastic sleeve

[Toby Thain]

On 2021-02-16 3:32 p.m., Dekatron42 wrote:
> I've had similar problems with two Russian CRT's and I had to use
> scalpel to cut them loose and then carefully peel them off as they had
> almost fused to the glass, probably from the plastizicer had evaporated
> but also left a thin film on the glass that worked almost like glue.
> 
> I tried to put them in warm water to soften them but I was afraid that
> they would shrink and crush the tube so I didn't use water that was
> hotter than from the water tap at home and that was not enough.
> 

Hi Martin,

Thanks, that's very helpful, not least the reassurance that "it's not
just me".

I imagine that getting them off was something of a carving operation. It
definitely feels "fused".

Out of interest, what type of CRT was involved? Here's an ebay picture
of the type I bought (although I don't have yokes for mine):
https://imgur.com/AGzrEDH

--Toby


> /Martin
> 
> On Tuesday, 16 February 2021 at 20:18:18 UTC+1 Toby Thain wrote:
> 
> Hi all
> 
> I have a crt with what looks to be a protective plastic sleeve over
> the socket and gun end (pictured: https://imgur.com/9exmkCq
> ). It isn't coming off with gentle
> pressure, are there any tricks other than careful destructive removal?
> 
> Thanks
> --Toby
> 
> -- 
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Re: [neonixie-l] Re: Dekatron for Demo Display

[Dekatron42]

No, unfortunately not, no hard figures - maybe Jon has. I've only read in 
some books about dekatron construction (neon tube construction in general 
where dekatrons are shown as special variations) that they have similar 
lifespans compared to small neon lamps but that the complex design 
complicates the failure modes/rate and also that keeping currents/voltages 
within the values specified in the datasheet will guarantee that they work 
as long as possible.

It depends on when you say a dekatron fails, it can get a silvery finish on 
the glass so you almost can't see the glow but it still works and it can 
fail a lot earlier than that due to internal flash-overs due to sputtering 
onto the ceramic material which means a current can flow in this sputtered 
material as the distance is shorter there compared to other paths (I have a 
few dekatrons with that failure and of course a few with a silvery look).

I have to count my dekatrons one day to see if I have enough to build a 
second Harwell WITCH. ;) :)

/Martin

On Tuesday, 16 February 2021 at 17:16:07 UTC+1 gregebert wrote:

> *Martin* - Do you know how long dekatrons last ? I have an A-101 running 
> as a spinner in one of my clocks, and it's been going 60RPM  24/7 for 
> almost 8 years with no signs of degradation. I use 30k dropping resistors 
> at the cathodes, and the current is right at the spec value of 450uA, so 
> that gives about 15V for "steering", and the driving waveform is 3-phase 
> with overlap. I
>
> On Tuesday, February 16, 2021 at 4:15:05 AM UTC-8 Dekatron42 wrote:
>
>> There is one more dimension to think about when running a dekatron and 
>> that is that over time it will degrade due to sputtering affecting the 
>> electrodes and to maintain a correct counting when it ages you should keep 
>> the voltages as described in the datasheet, especially the guide and bias 
>> voltages as those are needed when the dekatron nears its end of life - it 
>> is the same effect that is in play if you want to raise a dekatron from the 
>> dead if it has been heavily used or just stored for a very long time 
>> without use, raise the bias/pulse voltages and sometimes the anode voltage 
>> to surpass the effects of the sputtering - effectively increasing the 
>> current flow between the anode and the guides/cathodes.
>>
>> So even if dekatrons work at other voltages you will see the effects of 
>> lower/incorrect voltages when they near their end of life, this has been 
>> described in older litterature where the internals of dekatrons has been 
>> disected in detail - you might just need some 10V below the glowing cathode 
>> to move the glow on a new dekatron but as it ages it will stop working at 
>> that voltage.
>>
>> /Martin
>>
>> On Tuesday, 16 February 2021 at 00:53:36 UTC+1 bung...@gmail.com wrote:
>>
>>> Those values were left over from the 5v circuit. I was more concerned 
>>> with the level shifting from the PIC at 0 to +5v.
>>> Peter
>>>
>>> On Mon, Feb 15, 2021 at 6:48 PM Jon  wrote:
>>>
 I'd had a similar thought about increasing the bias resistors - it's 
 not necessary to run so much current (5mA) through that part of the 
 circuit.

 OK, so your proposed conditions are that the dekatron will see are 400V 
 anode to main cathodes; guides swinging from +25V to -25V with respect to 
 main cathodes. Tube current will be about 345uA.
 I've replicated these on my dekatron tester using a nice NIB GS10C/S as 
 the test subject and can confirm that they do work - the tube stepped fine 
 up at speeds up to over 4kpps once I'd woken it up a bit.

 Caveats:
 1) I only tried one tube.
 2) My circuit is rather different to yours so although the static 
 voltages are the same, the pulse shapes are almost certainly different. 
 And 
 we didn't even talk yet about pulse durations, so I've no idea what your 
 PIC is spitting out. But as long as you're not trying to cut things too 
 fine, there's lots of latitude to find patterns that work. Keep things 
 north of 100us per phase and you'll be fine unless you've got a really 
 reluctant tube.
 3) I was running at slightly lower current (300uA) so you've probably 
 got a bit more margin for speed than I had. Recommended operating 
 conditions are 325uA +/- 20%, so we're both inside that range. But a 
 little 
 more rather than less current is useful when pushing higher speeds. I'm 
 guessing though that you're looking for a much slower stepping speed for 
 this application though.

 If you've not already done so, I'd definitely second Martin's 
 recommendation to take a look at Michael Moorrees' dekatron work (he looks 
 in here from time to time too). He used a couple of elegant design tricks 
 which simplify the interfacing of dekatrons to modern electronics / 
 microcontrollers - I've followed his approach in pretty much all the stuff 
 I've built and it 

[neonixie-l] Re: Russian crt - foiled by plastic sleeve

[Dekatron42]

I've had similar problems with two Russian CRT's and I had to use scalpel 
to cut them loose and then carefully peel them off as they had almost fused 
to the glass, probably from the plastizicer had evaporated but also left a 
thin film on the glass that worked almost like glue.

I tried to put them in warm water to soften them but I was afraid that they 
would shrink and crush the tube so I didn't use water that was hotter than 
from the water tap at home and that was not enough.

/Martin

On Tuesday, 16 February 2021 at 20:18:18 UTC+1 Toby Thain wrote:

> Hi all
>
> I have a crt with what looks to be a protective plastic sleeve over the 
> socket and gun end (pictured: https://imgur.com/9exmkCq). It isn't coming 
> off with gentle pressure, are there any tricks other than careful 
> destructive removal?
>
> Thanks
> --Toby
>
>

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[neonixie-l] Russian crt - foiled by plastic sleeve

[Toby Thain]

Hi all

I have a crt with what looks to be a protective plastic sleeve over the 
socket and gun end (pictured: https://imgur.com/9exmkCq). It isn't coming 
off with gentle pressure, are there any tricks other than careful 
destructive removal?

Thanks
--Toby

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[neonixie-l] restoring GR-116D

[Adrian Godwin]

I have an old Racal-Dana counter in which the most significant digit has
areas that are dark. I'm putting this down to cathode poisoning, and want
to try restoring it.

There are some other peculiarities : that digit usually starts working
properly if I touch the anode with a DVM probe (but fails again at the next
power cycle), and it's also the one digit with a different batch code to
the other 4, though I don't think it has been changed in the past.

I've been through the DC supply and corrected any problems I can find but
it seems not to have enough current available to use it as a restoration
supply and also still drops sharply (briefly) when it sees the capacitance
of the DVM.

To try the increased-current method, I can generate the necessary voltage
and current more easily at AC than at DC. Should I do the extra work to
give it DC o does AC work too ? And should I be looking at the average
current, or the peak ?

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Re: [neonixie-l] Re: Dekatron for Demo Display

[gregebert]

*Martin* - Do you know how long dekatrons last ? I have an A-101 running as 
a spinner in one of my clocks, and it's been going 60RPM  24/7 for almost 8 
years with no signs of degradation. I use 30k dropping resistors at the 
cathodes, and the current is right at the spec value of 450uA, so that 
gives about 15V for "steering", and the driving waveform is 3-phase with 
overlap. I

On Tuesday, February 16, 2021 at 4:15:05 AM UTC-8 Dekatron42 wrote:

> There is one more dimension to think about when running a dekatron and 
> that is that over time it will degrade due to sputtering affecting the 
> electrodes and to maintain a correct counting when it ages you should keep 
> the voltages as described in the datasheet, especially the guide and bias 
> voltages as those are needed when the dekatron nears its end of life - it 
> is the same effect that is in play if you want to raise a dekatron from the 
> dead if it has been heavily used or just stored for a very long time 
> without use, raise the bias/pulse voltages and sometimes the anode voltage 
> to surpass the effects of the sputtering - effectively increasing the 
> current flow between the anode and the guides/cathodes.
>
> So even if dekatrons work at other voltages you will see the effects of 
> lower/incorrect voltages when they near their end of life, this has been 
> described in older litterature where the internals of dekatrons has been 
> disected in detail - you might just need some 10V below the glowing cathode 
> to move the glow on a new dekatron but as it ages it will stop working at 
> that voltage.
>
> /Martin
>
> On Tuesday, 16 February 2021 at 00:53:36 UTC+1 bung...@gmail.com wrote:
>
>> Those values were left over from the 5v circuit. I was more concerned 
>> with the level shifting from the PIC at 0 to +5v.
>> Peter
>>
>> On Mon, Feb 15, 2021 at 6:48 PM Jon  wrote:
>>
>>> I'd had a similar thought about increasing the bias resistors - it's not 
>>> necessary to run so much current (5mA) through that part of the circuit.
>>>
>>> OK, so your proposed conditions are that the dekatron will see are 400V 
>>> anode to main cathodes; guides swinging from +25V to -25V with respect to 
>>> main cathodes. Tube current will be about 345uA.
>>> I've replicated these on my dekatron tester using a nice NIB GS10C/S as 
>>> the test subject and can confirm that they do work - the tube stepped fine 
>>> up at speeds up to over 4kpps once I'd woken it up a bit.
>>>
>>> Caveats:
>>> 1) I only tried one tube.
>>> 2) My circuit is rather different to yours so although the static 
>>> voltages are the same, the pulse shapes are almost certainly different. And 
>>> we didn't even talk yet about pulse durations, so I've no idea what your 
>>> PIC is spitting out. But as long as you're not trying to cut things too 
>>> fine, there's lots of latitude to find patterns that work. Keep things 
>>> north of 100us per phase and you'll be fine unless you've got a really 
>>> reluctant tube.
>>> 3) I was running at slightly lower current (300uA) so you've probably 
>>> got a bit more margin for speed than I had. Recommended operating 
>>> conditions are 325uA +/- 20%, so we're both inside that range. But a little 
>>> more rather than less current is useful when pushing higher speeds. I'm 
>>> guessing though that you're looking for a much slower stepping speed for 
>>> this application though.
>>>
>>> If you've not already done so, I'd definitely second Martin's 
>>> recommendation to take a look at Michael Moorrees' dekatron work (he looks 
>>> in here from time to time too). He used a couple of elegant design tricks 
>>> which simplify the interfacing of dekatrons to modern electronics / 
>>> microcontrollers - I've followed his approach in pretty much all the stuff 
>>> I've built and it works a treat. Not to say that other approaches aren't 
>>> equally useful too of course.
>>>
>>> Jon.
>>>
>>> On Monday, February 15, 2021 at 9:39:13 AM UTC Dekatron42 wrote:
>>>
 I'd raise the resistance to at least some 100k for the two bias 
 resistors R5 & R6 in your diagram above.

 I'd also use the correct bias voltage and just use an MPSA42 with its 
 emitter to common ground for the driver to simplify the circuit as Ronald 
 Dekker and Michael Moorrees with their dekatron circuits.

 Different dekatrons need different bias and pulse voltages on the guide 
 electrodes to count properly so accomodating for those requiremenst will 
 remove a lot of problems and keep down the fault finding time.

 /Martin
 On Monday, 15 February 2021 at 03:05:12 UTC+1 bung...@gmail.com wrote:

> You are absolutely right. 5v was not high enough despite Ronald's and 
> my confirmation that it would work.
> I am changing to +25v and -25v and will have an optocoupler with the 
> diode driven from the 5v PIC and the transistor at the bottom of the 
> resistor between the two power supplies. It keeps it simple. I have 

Re: [neonixie-l] Re: Dekatron for Demo Display

[Dekatron42]

There is one more dimension to think about when running a dekatron and that 
is that over time it will degrade due to sputtering affecting the 
electrodes and to maintain a correct counting when it ages you should keep 
the voltages as described in the datasheet, especially the guide and bias 
voltages as those are needed when the dekatron nears its end of life - it 
is the same effect that is in play if you want to raise a dekatron from the 
dead if it has been heavily used or just stored for a very long time 
without use, raise the bias/pulse voltages and sometimes the anode voltage 
to surpass the effects of the sputtering - effectively increasing the 
current flow between the anode and the guides/cathodes.

So even if dekatrons work at other voltages you will see the effects of 
lower/incorrect voltages when they near their end of life, this has been 
described in older litterature where the internals of dekatrons has been 
disected in detail - you might just need some 10V below the glowing cathode 
to move the glow on a new dekatron but as it ages it will stop working at 
that voltage.

/Martin

On Tuesday, 16 February 2021 at 00:53:36 UTC+1 bung...@gmail.com wrote:

> Those values were left over from the 5v circuit. I was more concerned with 
> the level shifting from the PIC at 0 to +5v.
> Peter
>
> On Mon, Feb 15, 2021 at 6:48 PM Jon  wrote:
>
>> I'd had a similar thought about increasing the bias resistors - it's not 
>> necessary to run so much current (5mA) through that part of the circuit.
>>
>> OK, so your proposed conditions are that the dekatron will see are 400V 
>> anode to main cathodes; guides swinging from +25V to -25V with respect to 
>> main cathodes. Tube current will be about 345uA.
>> I've replicated these on my dekatron tester using a nice NIB GS10C/S as 
>> the test subject and can confirm that they do work - the tube stepped fine 
>> up at speeds up to over 4kpps once I'd woken it up a bit.
>>
>> Caveats:
>> 1) I only tried one tube.
>> 2) My circuit is rather different to yours so although the static 
>> voltages are the same, the pulse shapes are almost certainly different. And 
>> we didn't even talk yet about pulse durations, so I've no idea what your 
>> PIC is spitting out. But as long as you're not trying to cut things too 
>> fine, there's lots of latitude to find patterns that work. Keep things 
>> north of 100us per phase and you'll be fine unless you've got a really 
>> reluctant tube.
>> 3) I was running at slightly lower current (300uA) so you've probably got 
>> a bit more margin for speed than I had. Recommended operating conditions 
>> are 325uA +/- 20%, so we're both inside that range. But a little more 
>> rather than less current is useful when pushing higher speeds. I'm guessing 
>> though that you're looking for a much slower stepping speed for this 
>> application though.
>>
>> If you've not already done so, I'd definitely second Martin's 
>> recommendation to take a look at Michael Moorrees' dekatron work (he looks 
>> in here from time to time too). He used a couple of elegant design tricks 
>> which simplify the interfacing of dekatrons to modern electronics / 
>> microcontrollers - I've followed his approach in pretty much all the stuff 
>> I've built and it works a treat. Not to say that other approaches aren't 
>> equally useful too of course.
>>
>> Jon.
>>
>> On Monday, February 15, 2021 at 9:39:13 AM UTC Dekatron42 wrote:
>>
>>> I'd raise the resistance to at least some 100k for the two bias 
>>> resistors R5 & R6 in your diagram above.
>>>
>>> I'd also use the correct bias voltage and just use an MPSA42 with its 
>>> emitter to common ground for the driver to simplify the circuit as Ronald 
>>> Dekker and Michael Moorrees with their dekatron circuits.
>>>
>>> Different dekatrons need different bias and pulse voltages on the guide 
>>> electrodes to count properly so accomodating for those requiremenst will 
>>> remove a lot of problems and keep down the fault finding time.
>>>
>>> /Martin
>>> On Monday, 15 February 2021 at 03:05:12 UTC+1 bung...@gmail.com wrote:
>>>
 You are absolutely right. 5v was not high enough despite Ronald's and 
 my confirmation that it would work.
 I am changing to +25v and -25v and will have an optocoupler with the 
 diode driven from the 5v PIC and the transistor at the bottom of the 
 resistor between the two power supplies. It keeps it simple. I have to 
 order the optocoupler because none of my old ones have higher than 30 v 
 rating.
 I will have to think about the extra two power supplies. Maybe I can't 
 avoid them. It will be a few days until I get the parts.
 Peter
 [image: Dekatron Circuit.jpg]

 On Sun, Feb 14, 2021 at 3:18 PM Jon  wrote:

> Interesting approach - not seen it rigged up quite like that. Let us 
> know how it goes!
>
> My immediate question is whether there's a big enough potential 
> difference between an inactive guide