Propeller + Ethernet + Dekatron Tubes = ?
smbaker
Posts: 164
I hope nobody minds an oddball propeller project this weekend. 
I'm calling this thing the packetron-9000. It's designed to count the internet traffic flowing in and out of the router and visualize it on the dekatron tubes. It's probably my most complicated prop project to date, and the propeller was ideally suited to the many real-time tasks that needed to be performed -- servicing the ethernet port, counting on the dekatron tubes, etc. I haven't seen many threads in here on interfacing the prop with old technology (isn't it time someone produced a propeller nixie clock?), so hopefully some of the old timers will appreciate something with tubes.
There's 425 volts floating around in this box, and surprisingly I haven't fried anything yet.
Picture is attached, and a youtube video is: http://www.youtube.com/watch?v=aIWnGD92yKU. The narration was done late at night, so there's doubtlessly a few mistakes. There's a bit more information on my blog, but no schematics or listings yet.
I'm calling this thing the packetron-9000. It's designed to count the internet traffic flowing in and out of the router and visualize it on the dekatron tubes. It's probably my most complicated prop project to date, and the propeller was ideally suited to the many real-time tasks that needed to be performed -- servicing the ethernet port, counting on the dekatron tubes, etc. I haven't seen many threads in here on interfacing the prop with old technology (isn't it time someone produced a propeller nixie clock?), so hopefully some of the old timers will appreciate something with tubes.There's 425 volts floating around in this box, and surprisingly I haven't fried anything yet.
Picture is attached, and a youtube video is: http://www.youtube.com/watch?v=aIWnGD92yKU. The narration was done late at night, so there's doubtlessly a few mistakes. There's a bit more information on my blog, but no schematics or listings yet.
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Comments
@Heater, a few years back (ok, ok, a couple of decades back) I would have been happy to send you several dozen nixie tubes. I was so very very happy to replace them and the circuitry that drove them with leds. Unfortunately all of those nixies and other parts ended up being recycled or trashed as I was preparing to move.
Coincidentally I happened across this dekatron-based machine here in the UK recently whilst visiting the (British) national museum of computing: http://en.wikipedia.org/wiki/WITCH_%28computer%29
But now you got me thinking - I have a set of 4 Burroughs Nixies that came home with me in the late 60's that are prime candidates. Now I may have to go find a driver circuit! Tougher yet to find would be the sockets!
Hmmmmm
Driver was 7441 IIRC. For sockets you might be able to use female pins for DB connectors. Have to make a circuit board to mount them of course.
To answer a few questions -
1) The dekatrons aren't all that hard to find on ebay, although they tend to come from places far away. Mine came from the Ukraine, and took about a month to arrive. The one thing I've been unable to find is a decent source of 12-cathode dekatrons (for clock-like projects). Those seem almost impossible to find these days.
2) I don't know the rating of the hookup wire. It's sparkfun's "stranded hookup wire", but there isn't a datasheet for it. I agree that it would be a good idea to use something rated 450V or better for the high voltage connections, especially the one going from the power supply to the voltage divider board. Fortunately (and surprisingly) I never shocked myself from any of the high voltage connections.
For anyone who is considering a similar project, I've also been experimenting with MPSA42 transistors instead of the IRF840 mosfets. The MPSA42s are much cheaper and they don't suffer any of the problems that I experienced with the IRF840s with operation from 3.3V logic. I already have a replacement PCB on order to replace the mosfets with the MPSA42s. Also, another youtube video is online showing some experiments using a propeller education kit, MPSA42s, and a single dekatron.,
Now, there are guys out there making there own triodes. Which started me wondering, would it be possible to make ones own Nixie tubes?
Suitably shaped glass ware can be found easily enough. Think test tubes. Bending some wires around to make digits cannot be all that hard. The neon gas must be available, people are making signs with it all the time.
So, what materials would one need for best results? How do you get a good gas tight seal on the pins? What sort of level of pressure does one need to get down to inside? Has anyone done anything like this with neon or other gasses?
Jonathan
But dekatrons are gas-filled cold-cathode devices!
It's low pressure gas mixture, so air does get in over time. Perhaps the term gassy isn't quite right, but commonly used for these devices. Sigh. I sure wish I had found some good ones, and I have found a dozen or more but they are just never any good. So many fun things to use 'em with!
Not sure of the exact materials you would need, but one summer job I had was at a small company that made gas filled tubes to be used as light sources for pollution monitoring. One of the guys working there was a glass blower. He made the tubes, attached them to a vertical maze of glass tubing, chambers, and valves that looked like the typical mad scientist setup on TV shows, pumped the air out, and filled them with the appropriate gas. It really didn't look all that complex or difficult but I am sure that was because I was watching an expert at work. Once the tubes were filled he heated a small section that attached the tube to seal and separate it from the system.