last update: November-08-2003 (stay tuned!!)
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Start: November-02-2003
Dieter's
Nixie-Watch Project
last update:
November-08-2003 (stay tuned!!)
Back to
Dieter's Nixie Tube Page
Email
to Dieter
Start:
November-02-2003
I decided to develop one of the
smallest nixie clocks.
A German friend of mine, Ulf
Pambor (the Wristwatch- Guru) also will do
his part as designer for the housing and will help to develope
parts of the watch, especially the coding for the very tiny clock-
controller.
Here are my plans:
First, the tubes.
I first wanted to use the smallest Nixie tubes that heve been
made. These are the rare 4998 tubes.
They were made by Burrougs (B4998) and National Electronics (NL-4998)
Here you'll find the pictures and the data for that tubes.
B4998
NL-4998
Later you will see that I didn't use that tubes.
Step 1: The Power
Supply (Attempt 1)
Ok, the first problem is the power supply.
It's tricky to build up a high effiency switch mode power supply
which meets the following conditions:
Today I experimented around in
my workship.
There are lots of schematics for flash- cameras, which normally
all have negativ voltage output.
So I had to develop my own circuit specially for a Nixie -
Wristwatch with positiv output.
This was my first sketch:
I think I don't have to explain
how this simple oscillator works.
Some words: B1 powers over R1 the base of T1, which conducts,
current flows through the primary. Secondary delivers high
voltage, D1 and C1 are the rectifying- circuit. The guide-
winding delivers negative peaks for the cut- off of T1. Simple
and small!!!
The most important thing is the
transformer.
For a high efficiency and very small dimension a ring- core
should be best chioce.
I used this one for my first
attempt:
Short Data of that core:
Manufacturer: Amidon
Type: FT 37-77
Outer diam.: 9.5mm (!!!)
Inner diam.: 4.75mm
Height: 3.18mm
AL-value: 844mH/1000wdg.
The 300 windings are difficult
to wind.
First I used 0.025mm wire- what didn't work, because it's too
thin to wind.
It tears apart hundred times.
Therefore I moved to 0.1mm- which worked well.
It took me over 2 hours hard work to get this result for the secondary winding:
Keep in mind that this object is
only 10mm small. It's difficult tu hold it between the fingers.
And it's more difficult to wind 300 fu**ing.... windings on it ;-)
The primary and the guide- winding was easy to do:
There is little space in the drill-so, thicker the wire should
not be!!
I don't know the size of the wire of the primary and the guide. I
took what was laying around on my workbench.
OK... transformer was done.
I made the first ratsnest- experiment:
And..... I was surprised! It worked immediately. Not very well, but it worked:
Data:
Output Voltage: 170V (but only without load)
Output Voltage: 80V (with 3mA load)
Input Voltage: 2-2.5 Volts
Frequency: 40kHz
Here are the voltages measured at the base of T1 and on the
output of the core (D1, anode)
Just not good the the voltage drops. There will be a lot of work
on that circuit.
I was tired so I stopped for today.
November-04/05-2003
I got lots of emails with differet comments about the design and
the style of Nixie watches.
So I first sat down and made new thoughst about the case.....
See what I figgured out:
Design- Ideas
I made 8 different design - ideas.
The "arm" is 60mm wide- so you can imagine the original
size!
The sizes of the tubes also are real sizes.
Also the pictures have the same zoom-factors, so you can compare
the sizes easily.
 |
Design 1: My opinion: |
 |
Design 2: Advantages: - round shape looks cool - 4 digits (but not in one row) - much space inside for electronic and battery(s) Disatvantages: - too large ?? - heavyweight - difficult case - thick case - tubes not in the middle My opinion: I don't like the displaced tubes. |
 |
Design 3: |
 |
Design 4: |
 |
Design 5: Advantages: - rectangular shape fits better for the electronic and tubes - 4 digits with colon look cool - much space inside for electronic and battery(s) - flash cam transformer (no toroid- core to wind) Disatvantages: - heavyweight - thick case - 2 batteries? (a coin cell under the board possible ??) - I find round shape cooler My opinion: A good compromise for a 4 digit watch. The rectangular shape is not so cool, but acceptable. Maybe a bit too large?? |
 |
Design 6: Advantages: - rectangular shape fits great for the electronic and tubes - flat case - enough space inside for electronic and battery(s) - lightweight - simple case - flash cam transformer (no toroid- core to wind) - digits nearly in the middle. Disatvantages: - 2 batteries? (a coin cell under the board possible ??) - I find round shape cooler My opinion: A very good compromise for a 2 digit watch. Rectangular shape is not so cool, but acceptable. The outer dimensions will be the same as a round case. So the only benefit with the rectangular case is that there is more space than in a round case. |
 |
Design 7: Advantages: - rectangular shape fits good for the electronic and tubes - enough space inside for electronic and battery(s) - lightweight - simple case - flash cam transformer (no toroid- core to wind) Disatvantages: - I find round shape cooler - tubes not in the middle - thick case, also rectangular- looks not so cool! My opinion: Well, I don't like the shape and also the displacement of the tubes. Not what I really like, but a an alternative. |
 |
Design 8: Advantages: - rectangular shape fits good for the electronic and tubes - enough space inside for electronic and battery(s) - simple case - tubes in the middle - flash cam transformer (no toroid- core to wind) - flat case - 4 digits with colon look cool Disatvantages: - heavy weight?? (depends to materials) - I find round shape cooler - case approx. 70mm wide- is large! - 2 batteries (one also would be possible) My opinion: A good compromise for a 4 tube clock, but huge!! Maybe only for real enthusiasts. |
Resume:
A 4digit clock is large OR thick in every
case. It would be a clock, which you can not wear day by day, in
every situation.
So I will use that case later for a railroader clock (read above).
This will be really cool. For the wristwatch- project it's really
better to go to the 2 tube design, althought I would like 4
digits much more. OK, there's no question that a side viewed
Nixie is much better for a two digit clock, because the case will
be much flatter. I'm thinking about design 4 or 6. I'm not so
sure if the round shape is possible, it would be 50mm in diameter
and approx 20mm thick. This is pretty good. A rectangular shape
would also be 50mm x 50mm and also approx. 20mm thick. there will
be more space for the electronic inside, but also in the round
shape it would be possible I think. Maybe a multilayer board will
be necessary, but this is no problem at all. there's no question
that 2 coin cells will be better than 1 large battery, because so
the tubes are in the middle. Also the flash cam transformer is
better than my toroid core, because now I know that the
dimensions of them are much smaller than I thought and also the
efficiency is not as bad as I thought (thanks NEONIXIE- Gang!!).
So my favorite Design is #4 at the moment (provided that there is
enough space for the electronic). I must design the schematic and
the board first. I think a round case also will be cheaper. Also
this is a point we should not oversight. There will be no
standard case of course. They will be custom made and not a cheap
thing. But it's it worth for such a couriosity like a Nixie watch.
The design of the case means much to me, because I really like
noble looking things. A brushed or polished stainless steel
housing with a brushed stainless steel armband will look best I
think.
Now I'm asking
you:
WHAT IS YOUR FAVORITE
DESIGN???
Your comments are very
welcome!!!
November-08-2003
Tube decision:
The last two days I was lookoing for the smallest tubes for
Design 4 or 6.
I found very small ones, wich are not easy to get. They are side-view
(of course) and have very small dimensions.
The type and the dimensions are secret at the moment, althought I
know that they are very very hard to find. I have the luck to
know a source for them.
Driver:
The
The next steps will be:
- looking for flash cam transformers or old flash cams (difficult
in Germany, because less people use them) or any other small
transformers.
- developing the circuit
- experimental / test circuit
- coding (Ulf's job this time)
- developing the layout / routing and the board
- Decision which case we definitely will use. This MUST be done
after the layouting and routing, because we do not know if a
round case gives enough space. I will do 2 layouts. One rectangle
and one round shaped. so we'll see what's best. The case will be
Ulf's turn, and one of the final steps.
Comments welcome!!!
TO BE CONTINUED
SOOOOOON!!!!!
Thanks for reading.
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