What were you doing today at ten after ten? Over here, Carol and I had just left the garage on our trip down the mountain to go to church, and she was swapping in a new mix CD I had made to the 4Runner’s 6-CD changer. Not very cosmic, except in the sense that it was life proceeding as usual and well. Sure, my back still hurts (and for some reason, more than usual today) but Carol is by my side and my dogs are always happy to see me.
Better still, we went over to Wal-Mart after church and I found a species of dry-roasted peanuts without MSG, thanks to Jen Rosenau’s suggestion. They’re a little odd and not quite the dry roasted peanuts I’m used to, but tasty, albeit a little bit sweet. And lord knows, they’re cheap.
Ubuntu V10.10, Maverick Meerkat, was released today at 10:10 (I think; that’s the legend at least) South African time. I torrented it down earlier today in sixteen minutes flat, and will install it in the day or so. (I may try tonight if I don’t run out of steam.) It’s not a big-deal release, and I’m installing it immediately on its release to test if installing a Ubuntu version on Day 1 is less wise than waiting a month or two, as I’ve generally done in the past. I’m going to try Wubi this time, and will report in detail when it’s in and working.
I guess the best news of all is that I counted some Geigers today for the very first time. My radiation test sample is a 1950s aviation panel meter with radium paint on the scale and the pointer. After trying a number of transformers in the last two weeks I hit the jackpot with an old Merit A-2924 interstage transformer, which has the most extreme impedence ratio of anything in my formidable junkpile: 125 : 100,000 ohms. Alas, the spark gap only took the charge on the caps to about 550V. I swapped in a 1N4007 silicon rectifier diode instead of the spark gap and the charge went up to 900V without any trouble, using the pushbutton interrupter. The Geiger tube I have gives a loud signal into high-impedence headphones at 900V, but the volume goes down steadily and becomes inaudible under about 720V. This bodes ill for the notion of a steampunk Geiger counter (they didn’t have 1N4007s in 1900) but it was way cool to finally hear some clicks coming off the tube.
The interesting thing is that I get no reading at all from the 0A2WA gas rectifier tube, which was “salted” by a smidge of Kypton-85 in 1962. Half-life is 10.7 years; divide something in half four and a half times, and there isn’t really much of anything left.
There’s much more to try, and I’ll continue the series after I do some of that trying. But all in all, today was a very good day. I give it…a 10.
Two words, Jeff. Vacuum diode. What’s more steampunk than a nice, glowy vacuum tube?
It seems to me that when your voltage crosses the minimum plate voltage the diode can deal with, it will start to conduct, much as your spark gap does.
I have the mental image of using a gas regulator tube here, but that doesn’t seem like it’d be especially practical unless you put a few of them in series to get the desired voltage.
-JRS
-JRS
There’s some disagreement as to whether or not vacuum tubes are actually a little too new to be steampunk. Sparks, sure, but tubes are right on the edge. I’ll probably let somebody else decide that. Of course, any mad scientist who could fashion a Geiger tube in 1900 could fashion a Fleming valve or two, so it’s certainly not impossible. And being a mad scientist, he’s probably already figured out the physics.
One of the problems with using rectifier tubes is that the sort that can handle a 900V potential take pretty hefty filament current, and my goal in this is to make a unit that’s a little retro but also portable. On the other hand, there may be other solutions; I’ve barely explored the hand-cranked magneto option. We’ll see.
Edison discovered diode action in 1880 (he was not the first, apparently).
For a zero filament current diode, an off-the-wall answer is an 0Z4 or, considering the reverse voltage rating, several 0Z4s in series. Hard to beat 0 filament current and stay with tube technology.
Jack
I’ve never used an 0Z4 and don’t know much about them. Sniffing around online shows a lot of bad rep for the device, though nobody talks about the physical details of the failure mode. Sounds like they live fast and die young. Having dealt with a lot of flakiness in gas regulator tubes over the years, I wonder if hanging 0Z4’s in series (something I’ve never seen in a circuit nor spoken about) would actually work. It takes a few seconds for gas tubes like the 0C3 to “catch” and conduct, and given the brevity of the pulses out of the transformer, I wonder if I’d end up with anything all going into the accumulator caps. I’ll try it if I have a tube in the collection, but I’m not sure I’ll lay out money for them if I don’t.
Marx generator might also work. It uses spark gaps to generate a brief pulse that could charge a HV capacitor. http://en.wikipedia.org/wiki/Marx_generator
Cockcroft-Walton with diodes (vacuum tube?) is another approach.
http://en.wikipedia.org/wiki/Cockcroft-Walton_generator
Still think that a synchronous vibrator, or if you want to stick with a manual switch, a second set of switch contacts to act as a rectifier, should work.
Jack K8ZOA
I’ve done a little thinking about making an old relay “chatter” at a rate of four or five times a second, by using one set of contacts to make and break the coil current (with an RC time constant network to control the speed) and another to make and break the step-up transformer primary current. I have milk cartons full of old relays (tho admittedly few of them are operable at 3VDC) so it wouldn’t take a lot of benchwork to lash it up.
That other stuff is designed for extremely high voltage; the Marx guy uses 5,000 volts as the input to his multiplier. All I need to do is get to 900V. Two of those little glass-bead spark gaps might well do it, and once I find some (they don’t have them at my local junk shop) it may be worth a try.