Re: [neonixie-l] The SHINE experiment - Measuring the lifespan of nixies

[Dalibor Farný]

Hi Alex,

I can now access the website finally, interesting! About the Weston
book, You are right. It is too general and low level, there is no way
how to calculate actual sputtering rates using information provided
there. Also as You mentioned, they deal with low pressure mostly. But
there are some interesting information such as the experiment with one
shape of anode grid and different pressures. They found that the rate
of deposition of the metal on the glass at 20torr was much lower than
at 50torr, there is a relation between the shape (size) of the hole in
anode grid and pressure inside the tube.

I think it is better to spend a few hours setting up the real
experiment than bothering with theoretical calculations in this case.
There is too many variables - metal composition, anode cage shape,
purity of the gas and so..

I am definitely interested in your experiment as it is far the closest
to our needs!

Dalibor

2013/11/22 AlexTsekenis :
> Hi Dalibor,
>
> I just got confirmation from Eastern Europe that they can access the page.
> Can I ask who is your ISP/host in Czech Republic so I can check with our
> host. Thanks in advance. The same goes for anyone else that might be having
> issues. Glad you have temporary access!
>
> It seems our timing is good ;-) Certainly, Weston's book is idea for
> bed-time reading.The chapter on sputtering (ch 4) is informative of the
> state of research in those days, but it falls short if you are reading it to
> find out when the tube has reached its end of life. Here is why.
>
> The theoretical models presented (section 4.3) are too low level. The
> researchers tried to create models almost from first principles. The
> sputtering process is very complex, so they inevitably resorted in number of
> assumptions and simplifications. As you go through the chapter you will see
> that the results agree under some conditions, but disagree on others.I think
> Weston mentions this somewhere.
>
> In terms of experimental work most setups were at too low pressures to
> sustain a glow discharge (fractions of a torr). Consequently the
> back-diffusion of cathode material that is present in commercial nixie tubes
> was not present (as stated in top of page 138 and section 4.2.2) in those
> experiments. Additionally the ion beam setups look nothing like a nixie tube
> (mercury pool, charged collection target etc).
>
> As I described in SHINE, the most relevant experiments were those from
> Stocker (reference in SHINE page, page 140 in Weston's book). Stocker used a
> cylindrical tube with a wire cathode and a cylindrical anode (much like an
> IN-13 tube!). However he used a filament light source inside the tube,
> whereas we are using the emission from the glow itself as the light source.
> We are not using internal light sources as anything carrying current or
> being at a potential will distort the fields inside the tube. Stocker ends
> up with the empirical equation 4.18 in Weston's book or 2 in SHINE page
> which you one can use. But the equation only gives the sputtering rate, not
> the loss of brightness. To put the final nail in the coffin, none of the
> above experiments or theories incorporates anti-darkening measures such as a
> mesh anode like the IN-13 uses!
>
> We decided to measure brightness directly as at the end of the day that's
> what causes one to throw the tube away. Doing so automatically accounts for
> whatever processes might be taking place at an atomic level and any measures
> taken by the manufacturer to increase the lifetime. Using this method I
> cannot do a calculation and tell you how long a tube you made will last if
> you run it at 5 or 10mA. But I can measure it and then tell you with great
> confidence :-) hope this clarifies the distinction.
>
> As long as chapter 4 (and other literature on sputtering) is concerned, my
> personal feeling is that technology declined before the leaders at the time
> had time to develop a unified model. What do you think?
>
> Alex
>
>
>
> On Friday, November 22, 2013 5:25:29 PM UTC, Dalibor wrote:
>>
>> Hi Alex,
>>
>> I think it will actually be something with settings of the firewall on
>> your server. The server doesnt respond to ping, from my IP and even
>> not from my server that is in a big czech telehouse.
>>
>> however, I checked your site from the proxy and there is plenty good
>> information!
>>
>> I was just reading about sputtering two days ago, (Weston, 1968),
>> there were mentioned some experiments for measuring the deposit
>> thickness, have You already read it?
>>
>> Bye!
>>
>> Dalibor
>>
>> 2013/11/22 AlexTsekenis :
>> > Hi Dalibor,
>> >
>> > Thanks. I'm surprised you cannot access the site, no issues here from
>> > multiple computers. Maybe try from the home page
>> > http://www.saltechips.com/
>> > and clearing your cache. Please let us know if you are still having
>> > issues,
>> > there is a wealth of information on the site including equations, plots
>> > etc.
>> >
>> > We have data for the first

Re: [neonixie-l] A "small" project

[petehand]

On Monday, November 25, 2013 1:15:31 PM UTC-8, Michel wrote:
>
>
> Is that FET not warming up too much when you drive it directly from the 
> AVR output?
>

The FET doesn't warm up at all. The only reason it would warm up is slow 
turn-off time - the turn-on time is already limited by the inductor - and 
the AVR has plenty of drive, it can sink more than 40mA in brief pulses. 
Since the FET only sees half the output peak there's much less Miller 
effect, and careful layout also helps reduce feedback capacitance. I've 
actually had this circuit running with an SOT-23 FET, generating 50V at 
100mA for VFDs.

 
>

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Re: [neonixie-l] Re: New power supply design

[Chris Stalin]

Hey John,

Curious are the 600V model power supply complete?

Thanks

On Sunday, September 1, 2013 4:15:11 PM UTC-6, taylorjpt wrote:
>
> The 1474 design is for high power and high voltage (Up to 75W and up to 
> 600V on board, no multiplication).  It will be available in about 2 weeks 
> in the 150-300V adjustable version.
>
> 100W, 306V:  
> http://ppl.ug/iPAmeWyGAbI/
> New load bank: 
> http://ppl.ug/ZDU68hsXQik/
>
> I am also doing a refresh of the 1363/1364 based on the new controller in 
> the same time frame for about double the power (20W) of the original with 
> an extended input range: 5V to 36V.  The 2W+ efficiency should be in the 
> high 80s/low 90s.  This uses a significantly different control scheme and 
> will be silent at all input/output conditions.  The pricing on the refresh 
> will be the same as the original.
>
>

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Re: [neonixie-l] A "small" project

[AlexTsekenis]

Since you are doing a gated oscillator switching converter, you could 
consider using the on-board comparator of this particular MCU instead of 
the ADC. Might save you some code/CPU time.

Alex

On Monday, November 25, 2013 7:55:12 PM UTC, petehand wrote:
>
>
>
> On Monday, November 25, 2013 7:13:52 AM UTC-8, Chris Stalin wrote:
>>
>> LOL, Love it. Great work!
>>
>> Are you PWMing a FET for power from the atmega158?
>>
>> Yes I am. Given the current discussion here about AVR and Arduino, the 
> technical details are probably of some interest.
>
> Timer 0 is set up as fast PWM on the undivided 8MHz clock, with PWM output 
> to the OC0B pin (PORTD.5 in this case). The register settings are TCCR0A = 
> 0x23, TCCR0B = 0x09. I have the output compare register A (OCR0A) set at 
> 250 – this is the top limit of the counter and sets the PWM rate about 
> 40kHz. You can make it lower for higher frequency operation. Output compare 
> register B (OCR0B) sets the pulse width and is initially set low, around 
> 40. The OC0B pin goes high when the counter resets to 0 from 250, and goes 
> low again when the count matches OCR0B. The FET gate is connected to this 
> OC0B pin and turns on when the output is high. This counter is completely 
> free running and never stops, but the OC0B pin only drives the FET when its 
> port pin is set as an output, so the converter can be suspended without 
> disturbing the PWM by changing the port to an input. The port is 
> initialized as an input to avoid accidents, and is only set as an output by 
> the regulating routine once this is on the job.
>
> Regulation is performed with ADC channel 0. This is set to interrupt on 
> completion. The register settings are ADMUX = 0xE0, ADCSRA = 0xDE, ADCSRB = 
> 0. The high voltage is divided down with a couple of resistors – 200k to 
> the high voltage, 1k to ground, with the ADC input connected to the 
> junction. The ADC then reads 1/200 of the high voltage, comparable with the 
> ADC internal reference of 1.25V. The interrupt routine compares the read 
> value to a constant setpoint value, determined by experiment (200 for 175V 
> in my circuit). If the voltage is lower it increments the value of OCR0B, 
> and if higher, decrements it. If OCR0B is ever decremented to zero it sets 
> the OC0B port pin as an input to suspend the PWM, otherwise it sets it as 
> output. Finally it triggers a new conversion. Everything then happens 
> automatically, with no program intervention. Timer 0 OCR0B ramps up until 
> the set point is reached and thereafter hunts around that point as the load 
> changes, giving essentially constant voltage output. 
>
> For switching, I use an IRL640 MOSFET. This is a logic level FET with a 
> 200V rating, about the highest voltage rating you can get in logic level 
> devices. Its gate is connected directly to the AVR OC0B pin, with a 2.2k 
> resistor to ground to make sure it stays turned off when the pin is set as 
> input. The inductor is a Coilcraft MSD-1278-224 – this is a 220uH SEPIC 
> choke with dual coils. In my application the coils are connected in series. 
> The FET drain is connected to one end of the pair, the other end to the 
> rectifier, and 12VDC comes in at the junction. With this arrangement the 
> FET only sees half the peak voltage, so it has a good overload margin.
>
>
>  
>

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Re: [neonixie-l] A "small" project

[Michel van der Meij]

> The inductor is a Coilcraft MSD-1278-224 – this is a 220uH SEPIC choke with dual coils.> In my application the coils are connected in series. The FET drain is connected> to one end of the pair, the other end to the rectifier, and 12VDC comes in at the> junction. With this arrangement the FET only sees half the peak voltage, so it> has a good overload margin.That is neat, I had not seen that before. Interesting!
Is that FET not warming up too much when you drive it directly from the AVR output? In my clock I drive it from a 555 output but it get's quite warm, not too much I think because it runs like that for more than 6 months already. Using a gate driver chip with very low output resistance reduces the switching losses quite significantly. I use a TC4432 in another circuit, drive it from a PIC12F1840 output pin, since you already have a 12V supply, you then have a much larger choice for FET selection and can use a coil rather than transformer.Michel
 



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Re: [neonixie-l] A "small" project

[petehand]

Oops, I meant the 12V comes in one end and the FET is connected to the 
junction. The schematic is correct.

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Re: [neonixie-l] A "small" project

[Chris Stalin]

LOL, Love it. Great work!

Are you PWMing a FET for power from the atmega158?

Thanks

On Monday, November 25, 2013 7:45:50 AM UTC-7, Michail wrote:
>
>  Pretty.
>  
> I didn't see the order form.  :)
>  
> Michail Wilson
> 206-920-6312 
>  
>  In a message dated 11/25/2013 3:00:40 A.M. Pacific Standard Time, 
> pete...@gmail.com  writes:
>
>  [image: 
> https://lh4.googleusercontent.com/-LS5WWI-ky2c/UpMk2OK4BrI/AEc/yf_bxteNyBE/s1600/Altoid+Nixie1.jpg]
> I put this little guy together recently - I always wanted to see if it 
> could be done. I figure the audience here will appreciate it. It has 
> multiplexed IN16 tubes, driven by an ATmega168 AVR processor that keeps the 
> time and also generates the high voltage.
>
>
>
>
>
> -- 
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Re: [neonixie-l] A "small" project

[Michail1]

Pretty.
 
I didn't see the order form.  :)
 
Michail  Wilson
206-920-6312  

 
In a message dated 11/25/2013 3:00:40 A.M. Pacific Standard Time,  
peteh...@gmail.com writes:

 
 
(https://lh4.googleusercontent.com/-LS5WWI-ky2c/UpMk2OK4BrI/AEc/yf_bxteNyBE/s1600/Altoid+Nixie1.jpg)
 I put this little guy together recently - 
I  always wanted to see if it could be done. I figure the audience here 
will  appreciate it. It has multiplexed IN16 tubes, driven by an ATmega168 AVR  
processor that keeps the time and also generates the high  voltage.






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[neonixie-l] A "small" project

[petehand]

I put this little guy together recently - I always wanted to see if it 
could be done. I figure the audience here will appreciate it. It has 
multiplexed IN16 tubes, driven by an ATmega168 AVR processor that keeps the 
time and also generates the high voltage.





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