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 51 
 on: February 06, 2014, 02:20:02 PM 
Started by linux-works - Last post by Risen
it seems that if I choose to go non-mux, I can eliminate the driver transistors and basically just tie all anodes to +170v and simply send bcd nibble changes to each 74141 chip and latch them there until the digit/nibble changes.

You might not want to do this if you plan to have blank digits. While many 74141 chips use the high values (sending any hex digit A-F) as "blank" on the tubes, I've read that some don't, so that could cause an problem. At any rate, I found my chips to leak a fair amount of current when "off", so killing the anode line appears to be more efficient than sending a "blank" digit.

If you use I2C, make sure you add filter caps on the data lines. I ran an MCP23008 on mine to control the separators. The ArduiNix is noisy, though, and kept interrupting the I2C communication until I filtered it.

 52 
 on: February 04, 2014, 11:11:27 AM 
Started by linux-works - Last post by linux-works
thanks.

it seems that if I choose to go non-mux, I can eliminate the driver transistors and basically just tie all anodes to +170v and simply send bcd nibble changes to each 74141 chip and latch them there until the digit/nibble changes.

I measured about 2ma of current on my nixies and so with 4 nixies on at the same time, its only 16ma of current.  I would think that the 555 circuit can drive this, but I guess I'll find out Wink

if I use the arduinix shield, the transistors are there already and I guess I would either not map them to arduino pins or map them to a single pin and make that pin pwm-able so I can dim the lights.

I've used PCF i2c port expander chips before and will likely bring one in for the extra set of 8 bits I need.

I'll post the progress as I get further.

thanks.

 53 
 on: February 04, 2014, 07:41:21 AM 
Started by linux-works - Last post by Risen
Here's the best discussion I've come across:
https://groups.google.com/forum/#!topic/neonixie-l/gqA6OpDbdXM

 54 
 on: February 04, 2014, 07:34:27 AM 
Started by mfmjos - Last post by Risen
Bill -- That's a pretty good description of what's going on.

What I don't know is the sequence of the tubes - e.g. anode 1, cathode group 1 is the high order hours digit (or the low order seconds digit), etc.  Each combination will correspond to a time data element - you may have to play with that and you can always adjust it in the Arduino code.

There isn't a specific answer to that, because the ArduiNix doesn't have a predefined sequence. The sequence is created in the code.
For my clock, I chose:
A1 C0 - Hours high (tube 0)
A2 C0 - Hours low (1)
A3 C0 - Minutes high (2)
A1 C1 - Minutes low (3)
A2 C1 - Seconds high (4)
A3 C1 - Second low (5)
...which lights tubes 0+2, then 1+4, then 2+5, repeat.
But you can choose any sequence you can code.

I also built my own board and tube harness.
https://plus.google.com/u/0/photos/113825690086131396297/albums/5728271875401245617/5728271876241407938?pid=5728271876241407938&oid=113825690086131396297
https://plus.google.com/u/0/photos/113825690086131396297/albums/5728271875401245617/5865387316409291922?pid=5865387316409291922&oid=113825690086131396297
The harness photo didn't yet have the anode wires attached. I definitely recommend ribbon cable to keep the cables managed, but as you can see in the album I trashed the salvaged IDE (computer) cable I started with.


 55 
 on: February 04, 2014, 07:15:07 AM 
Started by bcage - Last post by Risen
On an Uno, the ArduiNix uses digital pins 2 through 13. Everything else is available to you.

For my build, instead of the downward-facing male headers that are included, I used stackable pass-through headers. This gave me access to all of the Arduino pins, which was great for adding other inputs, but also for debugging (and I needed a lot of that).

 56 
 on: February 04, 2014, 07:05:01 AM 
Started by bcage - Last post by Risen
My understanding is that the 74141 (and Russian equivalent) which the ArduiNix uses is not suitable for driving IN-18s. You might find some tubes and some chips which work together, but this is mostly by coincidence and not by design. Unfortunately the fix is to use a different driver circuit than what the ArduiNix provides.

 57 
 on: February 03, 2014, 03:00:01 PM 
Started by bcage - Last post by linux-works
I have seen posts that talk about the russian driver chip having some problems.  it seems there are good and not so good driver chips (from what I can tell, the ground that they give is not very low and so there is not a 'strong' circuit for the tube.  not sure why the 1 numeral is the issue but I have also read about that.

do you see this blue dot when you manually connect a cathode to ground (not using chips; just literally powering the tube from the 170v supply, connecting its anode to + and the 1-cathode to gnd?

 58 
 on: February 03, 2014, 10:01:12 AM 
Started by linux-works - Last post by linux-works
hi, new member here.

I'm trying to decide if I have to mux the nixies or if I can run them constantly on?

what are the design trade-offs or issues to worry about?

is it a dc-dc converter power issue?  will it overheat if you drive more than 1 digit at a time?  how many can you drive, safely, at a time?

is it a lifetime issue for the tubes?

my application (one of them) will be as a display of volume level inside an audio system.  if I don't have to mux the tubes, I'd just assume not.  it will be much less activity for the arduino and less noise inside my audio chassis.

I can add extra 'pins' via port expanders and I already have 2 shields that I can use for the 4 digits that I need.  I can mount one (or both) shields on a board by themselves and then wire them to the arduino along with extra port expanders to drive the 2nd shield.  the 2nd shield could have its own dc-dc 555 circuit on it to power its pair of tubes, if one 555 is not enough.

looking for some advice on this.

thanks


 59 
 on: February 03, 2014, 07:20:17 AM 
Started by mfmjos - Last post by mfmjos
Thanks for the reply.  What you describe is pretty much what I thought.  I did find some information on a website that helped (http://flockofbutterflies.blogspot.com/2009/11/arduinix-part-4-multiplexing.html).  I am not using IN-17 tubes so not prebuilt board for me.

Thanks for validating my suspicions.  I was hesitant to hook it up without a little more confirmation.  Maybe once I get it going I will put together a drawing and submit it here, for us noobs.

Here we go!

 60 
 on: February 02, 2014, 10:43:48 PM 
Started by mfmjos - Last post by bcage
I am probably the last one to be helping out since I am almost exactly in the same boat as you are... however, I have done something similar so I can try to help out.  First of all, if you are using the IN-17 tubes, you should probably get the pcb from robotpirate; that will basically wire the tubes for you.  If you don't have that tube, you will need to do something else.

First, you may have heard multiplexing mentioned for the Arduinix.  All that means is that not all tubes are lit simultaneously.  They are lit in sequence very quickly so that it appears that they are all lit at the same time.  The key to lighting the tube is the anode connection; think of it as the power and the cathode connections as the value (zero through nine).  To multiplex, the Arduino code will set the value for a tube and then turn on the anode for that tube to show the value.  Then it turns off the anode; changes the value to be what the next tube should be then turns on the anode for that tube... then it repeats for all the tubes.

You may have noticed, however, that the Arduinix has two sets of cathode connections (both zero to nine) and only 4 anode connections.  What the Arduinix does is use one anode to light two bulbs at a time with each set of cathodes providing the value for each of the two tubes.

This means that you will wire half of your tubes to one set of cathode pins on the Arduinix and the other half to the other set of cathode pins.  The anode connections will go across the two groups.

What this means is that you will need to wire half your tubes cathodes in parallel - this means make a connection from one of the cathode 0 pins to the "0" pins on half your tubes at the same time - think of a Y shaped connection from the Arduinix to each of the tubes or from the Arduinix to tube one then to tube two, etc... electrically these are the same.

Next wire the cathode 1 pin (from the same group of pins as the zero prior) to the "1" pins on those same tubes; 2 to 2; 3 to 3, etc... all the way to 9.  Call this group 1.

Repeat the same process for the other half of the tubes using the other set of cathode pins on the Arduinix.  Call this group 2.

Now, you will need to wire the anodes.  Note you have 4 anode pins on the Arduinix... since each lights two tubes at a time, this allows the Arduinix to drive a total of 8 tubes.  As described above, each anode will light two tubes.  You will wire from each anode pin on the Arduinix to two tubes; one from group 1 and one from group 2.  This last part is important or you will get tubes that are showing the same number since the cathodes in each group will provide a distinct value and the anode will light it up (so to speak).

What I don't know is the sequence of the tubes - e.g. anode 1, cathode group 1 is the high order hours digit (or the low order seconds digit), etc.  Each combination will correspond to a time data element - you may have to play with that and you can always adjust it in the Arduino code.

To summarize:

Each tube in group one has each of its cathodes connected to the group 1 pins on the Arduinix corresponding to the digit (0 to 0, etc)
Each tube in group two has each of its cathodes connected to the group 2 pins on the Arduinix corresponding to the digit (0 to 0, etc)
Each anode connects to a tube from group 1 and one from group 2

anode 1, cathode group 1 = something
anode 1, cathode group 2 = something else
anode 2, cathode group 1 = ...
through anode 4

Yes!  This is a lot of wires!  That is why the pcb route is much easier if you can find someone that has built one for your tubes.  I am using IN-18s... no such luck.  I do have some pcb sockets that will help a little, but I still anticipate a lot of wires and soldering... but, that is why I bought the kit instead of a finished clock!

If you don't know which pins on your tube correspond to each digit (they may not be sequential), you will need to google a "pinout" for your tube type.

I hope this helps.

Bill

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