4 digit nimo clock so far

[David Weiner]

Using a all spectrum electronics 4 digit clock chip outputting BCD running from a lm7805 off a 12 vdc 3a Wall wart using cd4028 BCD counters (also running at 12 volts ) a 1700 vdc high voltage power supply from three neurons ebay site And transistor level shifters 12 v to 5 v Each high voltage number output has a 1.2 meg resistor between the cd4028 output & the tube pin per number, I am now Working now to reduce the heat from the two 27 ohm resistors 2W across the 12 vdc
To give 1.1 filament voltage with a 6 volt bias
Mikes power supply is wicked good and works with a nimo tube

[Dekatron42]

Absolutely lovely!

/Martin

[gregebert]

@westdave -  I will be sending out my NIMO clock PCB for fab this week, and I'm unsure about the orientation of the display vs the tube pins. From the datasheet, the anode 'nib' looks like it should be in the 12-o'clock position for the digits to be vertical, but from your picture it looks like the anode was rotated slightly clockwise.

Any guidance would be greatly appreciated. Thanks in advance.

[westdave]

On Friday, April 20, 2018 at 1:38:26 PM UTC-7, Dekatron42 wrote:

Absolutely lovely!

/Martin

The high voltage nib input is very close to the 12 o clock of the tube call it  .5 of 1 o'clock

[threeneurons]

On Monday, April 23, 2018 at 10:34:29 AM UTC-7, gregebert wrote:

 

... I'm unsure about the orientation of the display vs the tube pins.

Go to page 4 of the following document:

 https://threeneurons.files.wordpress.com/2015/05/iee_nimo808.pdf

The anode "nib", is 18 degrees off of pin 12, making pin 11 roughly 9.7 degrees off of dead top center. The "Compactron" base has 27.7 degree spacing between pins, according to all documents that I could find.

From the tubes I have, the "nib" is top dead center. See the following photo:

Look at the internal structure. The nib seems centered within it. But the digits seem offset laterally:

 

[gregebert]

Thanks! That's basically how I have it oriented on the PCB layout. I drew an imaginary line through pins 5 and 11, and made that vertical. This is offset slightly from the diameter of the tube, and it puts the anode nib at the 12-o-clock position. Not quite where @westdave has his tube oriented, but I think it's close enough to fab the driver board. I'm hoping that whatever misalignment I have is within the tube-to-tube variations. If worst comes to worst, I could swap tubes around or respin the board.

Funny thing is, I've spent more effort and angst orienting the NIMO socket than I have for nixies on other PCBs, and all of those turned out fine.

94 nets to go on the mainboard routing...and no, I never use an autorouter.

[GastonP]

Ah! I didn't remember that specifications document... thanks for bringing it back, Mike.
Did anyone ever see any of those "four decade" tubes, or even the blue or red phosphor ones in the wild?
Not that I have the money to afford even one of this "more common" ones, but it's nice to daydream. :)
The six decade didn't even have a part number so we can safely assume was on the roadmap but never made it.

Gastón

[GastonP]

Thanks for bringing back the Nimo specifications, Mike.
Did anyone ever see the "4 decade" ones, or even the blue and red phosphor models?
The "6 decade" didn't even have a part number so it probably was in the product line roadmap but never made it.

Gastón

On Tuesday, April 24, 2018 at 3:53:01 PM UTC-3, threeneurons wrote:

[threeneurons]

That Nimo document, I actually spliced together into a PDF, from separate JPG pages on David Forbe's page:

http://www.cathodecorner.com/nixiedata/

I updated IEE contact information, and put David's & my "thumbprints", on it, so you can see how it bounced thru the internet.

The only Nimo's I've ever seen are the ones Westdave & I have. These A.J. Franzman stumbled upon, at C&H Surplus (Pasadena, CA) many years ago. He bought the lot, which wasn't that many. Westdave acquired some from him, and gave me two. We'd been sitting on them, til the Fan Blanche youtube video popped up, last October:

https://www.youtube.com/results?search_query=iee+nimo

They aren't the prettiest tubes, and you have to wonder what was IEE thinking ! They seem structurally complex. Much more complex, than a nixie. Interface, on the other hand is pretty simple. The HV (1800V +) on the anode is applied, and not manipulated. It only draws ~30uA. The filament/cathode passes 200mA, at 1.1V AC or DC. Digit manipulation, is all done thru the 10 grids. -4V (relative to the cathode), for full cutoff. This is where all the grids are "parked". Only the active digit's grid is brought positive, thru a fairly large resistor (330K minimum). Like all vacuum tube grids, it starts to conduct when it gets slightly positive. With the large resistor, the actual grid voltage just barely rises above the cathode level. Any cheap low voltage transistor, or simple 4000 CMOS device can drive it. My one digit nimo clock uses only common 2N3906 PNP transistors.