Lighting The Tube
The IN-17 Nixie I got from Sphere research corp got in and man is it beautiful! It was made in Feb 1983 in the good ol' CCCP per the markings on the tube. I plugged it onto a breadboard and connected the anode to my circuit's HV+ note and a random number's cathode to the node between the 150 ohm and 7.5kohm resistors like I had the load from last time. Lights up like a dream! I can see 142 volts across the anode and cathode with just under 300mV across that 150 ohm as predicted. The whole current is 1.72mA which is dead on as far as I'm concerned. The camera doesn't do it justice as I couldn't get my iphone's exposure down enough to get rid of the glow around the number. In real life the number is really crisp and clear. Holding it my hand, the IN-17 is a tad too big for a watch. I had not anticipated the nipple out the bottom, and the aspect ration of the height vs real-estate area is wonky. I'm going to have to use some american made tubes it seems.
The IN-17 Nixie I got from Sphere research corp got in and man is it beautiful! It was made in Feb 1983 in the good ol' CCCP per the markings on the tube. I plugged it onto a breadboard and connected the anode to my circuit's HV+ note and a random number's cathode to the node between the 150 ohm and 7.5kohm resistors like I had the load from last time. Lights up like a dream! I can see 142 volts across the anode and cathode with just under 300mV across that 150 ohm as predicted. The whole current is 1.72mA which is dead on as far as I'm concerned. The camera doesn't do it justice as I couldn't get my iphone's exposure down enough to get rid of the glow around the number. In real life the number is really crisp and clear. Holding it my hand, the IN-17 is a tad too big for a watch. I had not anticipated the nipple out the bottom, and the aspect ration of the height vs real-estate area is wonky. I'm going to have to use some american made tubes it seems.
Case Beginnings
I looked at Cathode Corner for inspiration again with the tubes. He uses the B-5870 tubes which were made by Burroughs but National Electronics has the same Nixie in the part number NL-5870. They come with a suffix either S or ST which I've found to be the standoff's height per the companies' catalogs (see below). I also made the decision to use an A1A (NE-2) neon tube for my first digit since its slimmer than a full tube and I can display the time (12hr only) and date (mmdd) just fine. I'll have to buy the tubes and see how different they look next to each other to make the final call though, for now we'll move forward with the draft design of the case with the skinny A1A tube to get me thinking mechanically.
I came up with two different designs which hinge on battery capacity. If I use a big battery (270mAh) then the case becomes more square-like and is pretty thick since the battery is thicker than the tubes. Or I could go with a smaller battery (120mAh) which allows for a more slim looking case with a bevel. I think I like that one better for now. The lower capacity isn't that bad since the watch is so easy to charge (wireless chagrining). One mistake I almost made was going to a coin cell li-ion with 120mAh. At first I didn't notice that the max continuous current was listed as 35mA which is way lower than what I'll be drawing while the nixies are on (140mA). The 120mAh lipo has a max current of >200mA which is perfect, wouldn't want the battery to overheat while I'm wearing it. I'm also trying to recess the tubes into the back board as much as I can to save on vertical height.
I looked at Cathode Corner for inspiration again with the tubes. He uses the B-5870 tubes which were made by Burroughs but National Electronics has the same Nixie in the part number NL-5870. They come with a suffix either S or ST which I've found to be the standoff's height per the companies' catalogs (see below). I also made the decision to use an A1A (NE-2) neon tube for my first digit since its slimmer than a full tube and I can display the time (12hr only) and date (mmdd) just fine. I'll have to buy the tubes and see how different they look next to each other to make the final call though, for now we'll move forward with the draft design of the case with the skinny A1A tube to get me thinking mechanically.
I came up with two different designs which hinge on battery capacity. If I use a big battery (270mAh) then the case becomes more square-like and is pretty thick since the battery is thicker than the tubes. Or I could go with a smaller battery (120mAh) which allows for a more slim looking case with a bevel. I think I like that one better for now. The lower capacity isn't that bad since the watch is so easy to charge (wireless chagrining). One mistake I almost made was going to a coin cell li-ion with 120mAh. At first I didn't notice that the max continuous current was listed as 35mA which is way lower than what I'll be drawing while the nixies are on (140mA). The 120mAh lipo has a max current of >200mA which is perfect, wouldn't want the battery to overheat while I'm wearing it. I'm also trying to recess the tubes into the back board as much as I can to save on vertical height.
Next Steps
I've picked out some new components to buy from mouser. A small 1:40 transformer to replace the giant guy in my circuit, a bunch of high voltage NPN and PNP transistors to switch the tubes, and few resistors for biasing. I'll post a schematic once they get in and I've wired it up. I also really want to buy the tubes right now so I can get it over with and work with concrete things but they're a bit expensive so we'll see if I can muster the courage to buy em now. My short term goal is to wire everything up with multiple tubes to an old micro-controller I have and see if I can control them fast enough to multiplex. Might take some tinkering, I haven't written code in years.
Reading List
Burroughs Tube Catalog
National Electronics Catalog
VCC Neon Indicator Lamps
Battery Space LiPo Vendor (270mAh and coin-cell battery)
All-Battery LiPo Vendor (120mAh battery)
I've picked out some new components to buy from mouser. A small 1:40 transformer to replace the giant guy in my circuit, a bunch of high voltage NPN and PNP transistors to switch the tubes, and few resistors for biasing. I'll post a schematic once they get in and I've wired it up. I also really want to buy the tubes right now so I can get it over with and work with concrete things but they're a bit expensive so we'll see if I can muster the courage to buy em now. My short term goal is to wire everything up with multiple tubes to an old micro-controller I have and see if I can control them fast enough to multiplex. Might take some tinkering, I haven't written code in years.
Reading List
Burroughs Tube Catalog
National Electronics Catalog
VCC Neon Indicator Lamps
Battery Space LiPo Vendor (270mAh and coin-cell battery)
All-Battery LiPo Vendor (120mAh battery)