Nixie Watch First Glimpse
Cobra007
not finished yet, at the moment it only counts from 00 to 59, but for
as long as that works, the rest is just a bit of coding.
This video shows the tubes at maximum brightness (which is about 2mA
DC average per tube @ 200mA battery current), and afterwards at
minimum brightness @ 6mA battery current. Efficiency is about 85% and
since I don't use resistors in the HV circuit, all this power is
converted into tube power (and a bit for the blue LEDs).
http://www.youtube.com/watch?v=AklybAgVMmk
Michel
J Forbes
Cobra007 wrote:
>
> http://www.youtube.com/watch?v=AklybAgVMmk
>
> Michel
Cobra007
about 13.5mm high. It fits nicely in the 16.5mm high, 50mm diameter
enclosure.
Michel
David Forbes
I'm glad to see that it's working! This is the point in the project in
which I'd be working on it 26 hours a day.
--
David Forbes, Tucson AZ
Dieter Waechter
David, when have you reached the 85% overall efficiency incl. anode
resistor?
I have never seen a current controlled design from you.
Only a design with about 50% overall efficiency if I remember well...
But I may be wrong, since I did not follow the topic.
Can you show us that design?
Dieter
Quixotic Nixotic
On 12 Apr 2012, at 02:50, Cobra007 wrote:
> I had a bit of time this week to get the first module working. It's
> not finished yet, at the moment it only counts from 00 to 59, but for
> as long as that works, the rest is just a bit of coding.
Well done that man. It's looking good.
John S
Lucky
Cobra007
finished :-) Have been looking forward to that for about 3 months now
since I came up with this plan.
Interestingly, I am not even surprised by the efficiency of the
circuit (I had predicted 80% - 90% in one of my first posts). The
thing that surprises me most is that you can actually run these tubes
on just 6mA battery current (I had predicted 20mA, so I was way to
conservative). Don't you think that is amazing? 6mA? The tubes look
very dark in the video at this low current, but honestly, if you walk
outside at night they appear just bright enough.
Michel
jb-electronics
the 6mA confuse me:
Even if your batteries supplied 12V, that gives you P = 12V x 6mA =
72mW. The tubes need at least 1mA at 150V (very conservative again),
which makes it P' = 2 x 1mA x 150V = 300mW.
Do you see my confusion? For that to work, your switching mode power
supply would have to have an efficiency larger than 100% ;-)
Your 20mA seem much more plausible. Are you sure you measured the
current correctly, or am I missing something?
Best regards,
Jens
Cobra007
It truly is 6mA average DC battery current (3.6V battery). It amazed
me as well, but the measurement is correct.
What you said is right, the tubes need a minimum current, say 1mA but
they don't need that all the time, you can PWM that which reduces the
average current to something much lower than 1mA. So although you PWM
that with say 1mA peaks, the average current is only a fraction of
that (about 1/25 if I remember well).
Michel
On Apr 13, 7:47 pm, jb-electronics <webmas...@jb-electronics.de>
wrote:
J Forbes
planning to use in the watch?
Cobra007
On Apr 14, 5:14 am, J Forbes <jforbnos...@selectric.org> wrote:
> What battery are you using in the prototype? is it the same one you're
> planning to use in the watch?
>
jb-electronics
thanks for clearing that up. I don't know, however, if the 6mA average
current makes sense as a value in itself, the ripple current on your
batteries (from 20mA to practically 0mA) might be more interesting,
especially if you are trying to estimate battery life.
What PWM frequency do you use, by the way?
Best regards,
Jens
Dekatron42
can expect!
A long life test with simulated user behaviour would be excellent, I
am sure that it is on your list but the sooner you show a figure of
that the sooner we (I) will know what to expect of the battery life.
Also as Jens says it is important to check what the battery
manufacturers say about sudden power usages from the battery as some
batteries do not like that at all. You might already have thought
about this and used a capacitor as the ripple current storage, I have
not seen any comments on that.
/Martin
Cobra007
changes to about 50mA at maximum current (200mA). I do smooth that out
with a parallel capacitor.
As it adjusts the tube brightness according to the amount of ambient
light, it is a bit difficult to say how long a battery will last. I
will need to measure an average reading over one day, or maybe even
one week. As what I can see now, I would say the average reading
requires around 50 - 75mA for say 1.5 seconds per reading. I am pretty
sure the battery will last for 1 year, but more accurate measurements
need to be done.
The battery I use is 750mAh and can easily supply 200mA. There's also
batteries that are around 1200mAh but can only supply 50-75mA. If the
watch is mainly used indoors, a long life battery would be sufficient.
Anyway, this all needs further testing.
Michel
Cobra007
The software is taking shape, it can display the time by motion
detection and return back to sleep.
The basis for the complete menu structure for all settings has also
been programmed.
At the moment it displays the time registers, but the registers
themselves are not updated yet.
Total circuit power is about 10uA during standby mode and 2uA during
deep sleep.
Deep sleep will be entered after a standby time-out to save battery
life. Clock will still run in deep-sleep mode.
I think it's about one more week to finish the program. It is very
structured and very flexible, exactly the way I want it to be.
Sometimes I leave it alone for a whole day, just to come up with the
perfect solution for a specific routine.
http://youtu.be/xOFn7Ovd0HA
Michel
Dieter Waechter
Am 20.04.2012 08:26, schrieb Cobra007:
> Second glimpse of the Nixie Watch.
>cut<
Cobra007
clocks? ;-)
Dieter Waechter
Best choice for a watch in this size I would say.
Hope you know someone who has a good stock of these ;-)
Dieter
jb-electronics
> Total circuit power is about 10uA during standby mode and 2uA during
> deep sleep.
> Deep sleep will be entered after a standby time-out to save battery
> life. Clock will still run in deep-sleep mode.
I am curious: Do you use an external interrupt to wake the processor in
case of a motion etc? This might be useful and could avoid the "standby
mode" altogether.
Jens
Cobra007
That's how I did it on my concept board, with an external interrupt.
Problem is that I need more components to be able to generate the
interrupt and believe it or not, it actually used more current.
Standby mode means the processor is in sleep mode but wakes up about 8
times per second to check the sensor. The sensor only uses 2uA but the
processor uses more current in sleep than in deep sleep mode, so all
together it is 10uA.
In deep sleep, the processor is completely powered down, only the RTCC
continues running. It can only be awakened by an external interrupt
(push button rather than motion sensor).
Michel
On Apr 21, 7:23 am, jb-electronics <webmas...@jb-electronics.de>
wrote:
jb-electronics
> Problem is that I need more components to be able to generate the
> interrupt
I would have used simple diodes that are OR'ed together to the external
interrupt pin.
> and believe it or not, it actually used more current.
Actually, I don't see that happening with diodes, do you? OK, if your
sources have different voltage levels you need shifters and these
require current, of course.
> Standby mode means the processor is in sleep mode but wakes up about 8
> times per second to check the sensor. The sensor only uses 2uA but the
> processor uses more current in sleep than in deep sleep mode, so all
> together it is 10uA.
Have you played around with the configuration bits? I once realised that
a silly enabled Brown-Out detect (which makes no sense with
battery-powered devices) takes up almost all the current.
Sorry if this has been mentioned before, but which processor do you use?
Best regards,
Jens
Cobra007
short but very strong IR pulse, I'd have to check the exact numbers
but it is somewhere around 250mA for 2 or 3 usec. The IR light
reflects from an object above the watch (a hand for example) onto an
IR photodiode. To make this work in all situations, the photodiode
should not saturate when there's a lot of light around (say you are
outside in the sunshine), so it's series resistor is relatively low
(which also helps making it very fast) and the signal received from
the powerful 250mA pulse is only like 40mV.
I first built that with some gates, capacitors and resistors. It
worked very well but used about 400uA average current if I am not
mistaken.
10uA is pretty much what it should be according to the data sheets if
you add up all the currents. Honestly, a battery will last for ages
(about 8 years) with a 10uA load, so I am really not worried about
that. It's just that the processor supports deep sleep mode, so I'd
like to incorporate that as well
Michel
On Apr 21, 7:59 pm, jb-electronics <webmas...@jb-electronics.de>
wrote:
jb-electronics
you are right, I did not assume it was so complicated. However, have you
considered using frequency modulation of the IR signal? This way you
could easily subtract daylight digitally.
Jens
Cobra007
I know you can make things in 1,000 different ways but in the end, it
is powered by a battery which basically means your solution cannot use
more than say 5uA average current. There is not a lot you can do with
that :-) And secondly, the ideal solution would preferably fit within
1 cubic mm :-).
Michel
On Apr 21, 9:01 pm, jb-electronics <webmas...@jb-electronics.de>
wrote: