Found myself looking at my current desk paperweight and thinking it could have come out of an engineering shop any time in the last 100 years looking exactly the same
Is that an AVO6 you've got there? I've got a 7 and 8, but that looks older than both of them?
These? Definitely not an Avo anything. They're both around 1920s I think. I've got an Avo 6 somewhere in a large box of ancient electrical test equipment I think.
No they're not. The one on the right hiding in the gloom looked to be an early AVO but not with a wooden case and single scale. My 8 still gets used occasionally, there are times when you can't beat a big moving needle over a digital display.
True- last time I used the Avo was testing the feedback pots in the blend motors.
I'm very fond of those old volt and ammeters on the windowsill, hand painted dials and all that. Not sure that I'd actually want to use them for their intended purpose though. They're a bit battered.
I don't think you'd want to use anything like that for absolute measurements but to watch a varying voltage or resistance on blend motors, lambda sensors and the like, they can't be beaten (other than by a scope......).
I was wrong- my Avo is a model 40. It's a 1942 model.
EDIT- sparked (!) up my interest in it, it was actually made in June '43. Now I've got it out, I'm going to treat it to some new batteries as only the 9v (4.5 x 2) high resistance side works and the 1.5v low resistance side is dead.
I'm just impressed that they managed to salvage so much stuff off the Titanic.....
I really wish I could find the pictures I took of a piece of industrial junk we found at work. It was a mercury tilt switch from the original stand by generator. It was massive and contained about 6 litres of Mercury. Amazing glasswork and bloody heavy.
How did you get rid of the mercury? Pour it in the castle duck pond? I bet they wouldn't take 6L of mercury down at the local tip!
:)
I suspect it had a commercial value, judging by the speed the sparky offered to "look after it" :)
edit: I mis-remembered. It was actually some kind of transformer, or maybe rectifier. Real Frankenstein's lab type stuff :)
I seem to remember the mercury arc rectifier being the topic of a particulary inspiring lecture back in my days as a student at Kingston Polytechnic.
Orangebean wrote:
I seem to remember the mercury arc rectifier being the topic of a particulary inspiring lecture back in my days as a student at Kingston Polytechnic.
I've a picture of one of those in operation somewhere. It was taken on a substation inspection whilst I was on an asset condition survey of Melbourne trams a few years ago.
Quite spectacular, I'll see if I can dig it out.
Here we go...
We have a lot of mercury tilt switch relays in our stations, old BT ones for firing the station bells when the backup phone goes. They use one of those tall skinny BT relays on its side in a heavy cast box, with a pushrod going up through a barrier to a "seesaw" with a vial of mercury that rocks backwards and forwards. I'll post up a video later when I can get it off my phone.
Very Hollywood, GeorgeB. Kind of what I remember from that lecture in the last century
Yep, that's the sort of thing. Different shape, but definitely of that ilk. There was a very impressive puddle of Mercury at the bottom so it was left well alone in case the glass broke as we wrestled with it.
Orangebean wrote:
Very Hollywood, GeorgeB. Kind of what I remember from that lecture in the last century
I'd never seen one before (and haven't since) so the first reaction was, "What the fu*k?!"
It definitely looks like it should be hovering over a lonely prairie somewhere, firing off tractor beams at passing pickups.
Great photos but IMHO definitely from Mars......
https://en.wikipedia.org/wiki/Mercury-arc_valve
.... or The Isle of Man....
I would love to see one of those rectifiers in person. With a load on it too, as they change intensity as the load increases/decreases.