Re: [neonixie-l] Who simulates or protoypes their designs before doing a PCB ?

[gregebert]

I've heard of Proteus and Falstad, but never looked into them because I'm 
entrenched in my current suite of free CAD tools and so far I havn't seen 
anything that will nudge me out. The biggest fear I have is that a tool 
will get abandoned, so having them installed on my local system is a must. 
So far, the gEDA tools haven't been abandoned yet, but it's been a few 
months since the latest update. 

On Tuesday, March 26, 2024 at 12:45:02 AM UTC-7 Tom Nolan wrote:

> I've been using Proteus for many years.  I'm sure I've saved lots of money 
> on wasted boards.  Also often see better ways of doing things while 
> simulating.
>
> Tom
>
> On Sat, Mar 23, 2024 at 11:41 AM gregebert  wrote:
>
>> Just curious to know how many of you run logic and/or analog simulations 
>> on your designs before doing a PCB, or if you do any prototyping.
>>
>> Since I'm a longtime designer of IC's, I rely heavily on simulations: 
>> ngspice for the analog sections, verilog for the entire PCB (logic, FPGA if 
>> any, and analog). Once that is done, I go straight to PCBs with no 
>> prototyping. So far, I've only had 1 project that required any 'blue wires' 
>> to fix a design error.
>>
>> -- 
>>
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>>  
>> 
>> .
>>
>

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Re: [neonixie-l] ScopeClock with teensy4.0

[Anders Mikkelsen]

To give some more context around some of the design decisions, I'll do a 
quick summary of the power supply design process here:

A main goal was to only use off-the-shelf magnetics. The transformer was 
chosen to have the highest available HV winding magnetizing inductance, to 
limit the reactive power in the Baxandall oscillator. Flyback transformers 
are deliberately wound to have a low magnetizing inductance, so they are 
not perfect for this application, but the chosen part works pretty well.

I originally looked at using the transformer in flyback mode, but this is 
not ideal for running voltage multipliers as the turn-on current in the 
switch (from charging the multiplier stack) is only limited by transformer 
leakage inductance, which interacts badly with peak current mode control. 
There are workarounds like using non-PCMC-controllers (as done in the 
original SCTV design), using fixed-on-time or hysteretic controllers, or 
filtering the current sense signal, but I wanted to explore something 
different. I had worries about startup behavior and control range in a 
self-oscillating design like this, but it behaves very well in my testing 
so far.

A cheap buck pre-regulator is used to control the secondary voltage. This 
part has not been fully tested yet, but the board has provisions for 
mixed-mode feedback to stabilize it if this turns out necessary. 

All voltages are doubler-derived to improve cross-regulation, to minimize 
focus variation when the cathode current (brightness) is adjusted. If a 
single secondary is used, this means more stages are needed for the PDA and 
cathode voltage multipliers, since the deflection voltage is limited to 300 
V in order to manage dissipation in the deflection amplifiers while 
maintaining acceptable slew rate. Luckily the transformer has a tapped 
secondary, so I can get 300 V for acceleration, and 550 V per stage in the 
other multipliers. 

One issue I found in my original design is that focus, brightness and 
astigmatism interact to a large degree. This turned out to have two main 
causes. One was sagging of the anode 2/4 voltage from the screen current, 
here I ended up buffering the astigmatism voltage with an emitter follower 
to make this supply stiffer while not having excessive dissipation in the 
potmeter. The second issue was that the cathode voltage moved around a lot 
relative to VG1 and focus due to the cathode being driven from a resistor 
chain. I originally expected that most of the cathode current would end up 
as beam current, but most of it actually goes to the control grid, as much 
as 90+ percent. This means that the cathode current was about 10 times 
higher than I expected. The trick here is to drive both the cathode and 
control grid from low impedance sources. Here I solved it with deriving the 
control grid voltage from a separate multiplier running off the filament 
supply, instead of the common divider chain that some other designs use.

Filament power is derived from another parallel transformer, I chose a gate 
drive transformer for its good isolation rating and low cost. I went with 
inductive current limiting on the secondary side for a few reasons. 1: it 
provides current limiting behavior during start-up, giving gentle warmup of 
the filament. 2: It allows easy selection of filament voltage by just 
changing the inductance without modifying the transfomers. 3: it allows the 
secondary voltage to be higher than the filament voltage, requiring less 
stages on the voltage multiplier in order to reach the target -Vg1 voltage. 
4: It provides some tank VARs to keep the Baxandall oscillator from 
dropping below the minimum required Q during startup with a cold filament.

The last trick is the -12 for the deflection amplifier constant current 
sinks. I played with different designs for the deflection amps, and found 
the simple long tailed pair with a CCS to work exceedingly well for its 
simplicity. The cheapest way I found of making the required negative rail 
for this was to make a capactive divider as part of the primary tank 
capacitance, and rectifying the voltage across the middle cap, which works 
fine since it's isolated by caps on both sides. It looks a bit funny, but 
works very well.

On Sunday, March 24, 2024 at 7:48:53 PM UTC+1 Anders Mikkelsen wrote:

> I know I'm a bit late in following up on this, but better late than never! 
> I got caught up in life and other projects as usual.
>
> I've put up some more photos and videos, plus some preliminary schematics 
> in this google album: https://photos.app.goo.gl/dzu7QLQbDr4ameMr8
>
>
> Best regards
>
> On Saturday, December 23, 2023 at 2:10:19 AM UTC+1 Max Di Noi wrote:
>
>> Actually, that code works well! I had a typo on a pin config. Seems to 
>> work well! Very pleased. I hope you find that snipped of code useful.
>>
>>
>> On 22 Dec 2023, at 17:58, Max DN  wrote:
>>
>>
>> Jörg,
>>
>> This is the code that I am using with DAC 4822 (similar to 4922 but with 
>> 

Re: [neonixie-l] Today's eBay Bargain

[Peter Hall]

Very Second hand,not Nos...$230aussie...  WoW...FromPeter Hall insidiousnixies輦Utube On 22 Mar 2024 10:33 pm, Nick Andrews  wrote:And more insanity?https://www.ebay.com/itm/256454150888?mkcid=16=1=711-127632-2357-0=nCq7TSpgRJ6=2047675=9S4jfnnKS4i_ver=artemis=COPYOn Fri, Mar 22, 2024 at 3:12 AM Adam Piórko  wrote:The prices of both IN14 and NL7037 are insane.I'm keeping an eye on the NL7037 listing - the seller has already lowered the price...środa, 20 marca 2024 o 01:10:27 UTC+1 Nicholas Stock napisał(a):At least it's an actual nixie tube and not one of the plethora of 'Nixie' clocks using edge lit acrylic.However, that price is insanity... as is this NL7037...https://www.ebay.com/itm/134955060322Each to their own though...On Tue, Mar 19, 2024 at 5:03 PM d4myli  wrote:Stupid seller using his kid’s hand -- Original --From: Mac Doktor  Date: Wed, Mar 20, 2024 1:13 AMTo: neonixie-l Subject: Re: [neonixie-l] Today's eBay Bargainhttps://www.ebay.com/itm/375319887308?itmmeta=01HSBR7DTV6BF98VJD376C88H3Biggest IN-14 I've ever seen and the price is equally huge. It does have the plastic thing on it. That's got to be worth at least fifteen dollars.
Terry Bowman, KA4HJH"The Mac Doctor"https://www.astarcloseup.com"There is no Main Street anymore except at Disneyland—and try and buy a gun there"—Hank Hill







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Re: [neonixie-l] Who simulates or protoypes their designs before doing a PCB ?

[Tom Nolan]

I've been using Proteus for many years.  I'm sure I've saved lots of money
on wasted boards.  Also often see better ways of doing things while
simulating.

Tom

On Sat, Mar 23, 2024 at 11:41 AM gregebert  wrote:

> Just curious to know how many of you run logic and/or analog simulations
> on your designs before doing a PCB, or if you do any prototyping.
>
> Since I'm a longtime designer of IC's, I rely heavily on simulations:
> ngspice for the analog sections, verilog for the entire PCB (logic, FPGA if
> any, and analog). Once that is done, I go straight to PCBs with no
> prototyping. So far, I've only had 1 project that required any 'blue wires'
> to fix a design error.
>
> --
> You received this message because you are subscribed to the Google Groups
> "neonixie-l" group.
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> https://groups.google.com/d/msgid/neonixie-l/acf7f9a1-2cf2-4997-9f21-9ae30c929960n%40googlegroups.com
> 
> .
>

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Re: [neonixie-l] Today's eBay Bargain

[Nick Andrews]

And more insanity?

https://www.ebay.com/itm/256454150888?mkcid=16=1=711-127632-2357-0=nCq7TSpgRJ6=2047675=9S4jfnnKS4i_ver=artemis=COPY



On Fri, Mar 22, 2024 at 3:12 AM Adam Piórko  wrote:

> The prices of both IN14 and NL7037 are insane.
>
> I'm keeping an eye on the NL7037 listing - the seller has already lowered
> the price...
>
>
> środa, 20 marca 2024 o 01:10:27 UTC+1 Nicholas Stock napisał(a):
>
>> At least it's an actual nixie tube and not one of the plethora of 'Nixie'
>> clocks using edge lit acrylic.
>>
>> However, that price is insanity... as is this NL7037...
>>
>> https://www.ebay.com/itm/134955060322
>>
>> Each to their own though...
>>
>> On Tue, Mar 19, 2024 at 5:03 PM d4myli  wrote:
>>
>>> Stupid seller using his kid’s hand
>>>
>>>
>>>
>>> -- Original --
>>> *From:* Mac Doktor 
>>> *Date:* Wed, Mar 20, 2024 1:13 AM
>>> *To:* neonixie-l 
>>> *Subject:* Re: [neonixie-l] Today's eBay Bargain
>>>
>>> https://www.ebay.com/itm/375319887308?itmmeta=01HSBR7DTV6BF98VJD376C88H3
>>>
>>>
>>> Biggest IN-14 I've ever seen and the price is equally huge.
>>>
>>> It *does* have the plastic thing on it. That's got to be worth at least
>>> fifteen dollars.
>>>
>>>
>>>
>>> Terry Bowman, KA4HJH
>>> "The Mac Doctor"
>>>
>>> https://www.astarcloseup.com
>>>
>>> "There is no Main Street anymore except at Disneyland—and try and buy a
>>> gun there"—Hank Hill
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "neonixie-l" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to neonixie-l+...@googlegroups.com.
>>> To view this discussion on the web, visit
>>> https://groups.google.com/d/msgid/neonixie-l/EE6CD6FD-5E4F-4747-A140-C220C72F6289%40gmail.com
>>> 
>>> .
>>>
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>> To view this discussion on the web, visit
>>> https://groups.google.com/d/msgid/neonixie-l/tencent_46361DE3680DC439C44CA2B4%40qq.com
>>> 
>>> .
>>>
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