I currently build a getter flasher according to Ron Soyland‘s design (he will publish it on his site soon). There is a few photos from the building process:
Soooo.. After six weeks of intensive development, I am posting first photo of finished ShanghaiTime clock. As I already wrote, I designed this clock for a glass-art contest “When Prague Meets Shanghai” arranged by a czech company producing high-end glass chandeliers called Preciosa. I plan to write more, attach some photos of the innards, electronics etc., this blogpost is just about to share my excitement from how great it turned out to be on a photo!
The ShanghaiTime clock, photo: janskrasek.com
I am working hard on a clocks for a contest called “When Prague Meets Shanghai” (more about contest here: WPMS). This is a first oportunity how to present working tubes in a real product.
I experienced big success today. I sealed first really working nixie tube (or nixie retort ;-). I surprisingly didn’t forget to do any individual step in the making process and ended up with a tube that by far exceeded my expectations.
I tested the tube carefully on the helium leak detector several times, I also checked all the vacuum system, gass filling manifold and gas connectors. I found one small leak on the teflon washer on one of the needle valves (for neon filling) – repaired – and one on the connector to neon bottle – placed a new o-ring. I pumped down all the vacuum system for several hours, gass filling manifold included. I then rinsed both gas branches with gases to get rid of remaining air, closed both needle valves and made a overpressure in those branches so that no air would get in. It turned up that this step was critical for gas purity.
The tube was baked out to 410C (then it broke down, should go to 480C) and then it was filled with neon and argon (5×10-2 torr of argon accorging to thermocouple – very inaccurate value).
Number “0” is not working as the wire sticking out of the tube broke off 🙁 Also the stainless steel assembly inside is attacked by something that made it “rust” 🙁 I don’t know what.. The tube has so strange shape because I didnt have a tubing of so large diameter, so I had to blow it from smaller one..
The most important thing is that I achieved values of striking voltage that are almost like industry made tubes! That is the most important thing for me!
1 – 139V
2 – 136V
3 – 141V
4 – 140V
5 – 131V
6 – 149V
7 – 126V
8 – 124V
9 – 136V
Finally, the shed is finished and I can start moving all the equipment that I gathered in recent two years there. Building of the shed was the major job during last 5 months, I didnt have much time for real nixie tube research, but that changes! I made the glassblowing stuff working today – torches, propane-butan bottle, oxy concentrators, manifold and so.. I also moved some of the stuff here, it is waiting to be sorted out..
I made some minor changes is the last nixie tube design and decided to get it etched from brass. It would be better to have it made from stainless steel, but the company I use for etching experience some problems with photo resist, so I decided to use a brass, only for this test. Brass is nice material, it is unfortunately impossible to use it in vacuum tubes. It relieves a zinc into vacuum during a bake out phase, the zinc then condensates on the colder glass envelope.. It is also too soft and numbers made from brass would sputter heavily.
This assembly should be fully working, the numbers are insulated by ceramic beads and the wire inside them is insulated by thin glass tube. There are no shorts. I plan to put it into vacuum chamber to test its behaviour, glow evenness, brightness, breakdown voltage and so..
The mica sheets were cut by scissors, I plan to make a circular cutting knife and use a press to produce nice and even circle..
New addition to the workshop, Heathway glassblowing lathe. I got it on eBay and it took almost a month to arrange a trasport from UK here to Czech republic. But it finally came off and it is now sitting firmly on the concrete block for my future garden lab (masked as garden shed) 😀 This lathe was manufactured in 1968 in UK and served all its life in a university glassblowing lab. That lab was cancelled around 2012 and the equipment was sold out.
I am currently spending all my time building the shed so that I can accomodate all the stuff here. Once it is finished I will feed You with glowing wires continuously 😉
I plan to use that lathe for doing all the glasswork for nixie tubes..