Sledgehammer's Cycles

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Friday, November 16, 2012

Happy birthday, Vacuum Tube!

On this day in 1904, the electrical Vacuum Tube was patented.  It revolutionized the world, allowing electrical (as opposed to mechanical) switching.  Forty years later, it was the core technology of ENIAC, the world's first computer.






I remember Gray Beards who called these by their old name, "valves".  That is a great way to think about them, with electrical current representing flowing water in pipes, and vacuum tubes acting as valves to open and close the pipe.  And I remember listening to baseball on our old 5 tube superhet radio.

9 comments:

Anonymous said...

All my EE. Classes at college were tube theory based - very little solid state. The old profs just couldn't see the future ..... Or didn't. Understand how to teach for it.

NotDilbert

Roger said...

I recall our radios and televisions, when they stopped working we would take out all of the "valves" and hie them to the local hardware store. There they had a machine with multiple sockets, plugs wires and switches along with charts. We would look up and test each tube until we found the failed unit, buy an new one and return home triumphantly. We then re-installed all the tubes, using the handy chart on the back of the radio or TV.
Today, we just buy a new radio or TV because its cheaper to do that than pay to repair the old.

BobG said...

I remember those days, Roger.
When I first started tinkering with electronics as a kid, transistors were still fairly limited, so we studied tubes (this was the early sixties).

Dave H said...

Roger: I worked in TV repair while I was in college, and people who tested their own tubes were a steady source of income. Not everybody realized that each tube had to go back in the same socket it came out of.

That's why we had a sign in the shop. "Repair Rate, $25/hour. If you watch, $50/hr. If you help, $100/hr. If you already worked on it, buy a new one."

Paladin said...

I've got 5 tube radios that work (4 bakelite cased and one wooden floor radio). That's not counting the ones that I own that don't work currently. Those are just for lookin' at :) I restore the cases on them, but the "guts" are beyond my ken.

drjim said...

I grew up with tubes, learned them well, and then transitioned to solid-state. When FETs came along, the solid-state guys couldn't understand them because they act more like tubes than transistors.
Tubes are VOLTAGE controlled devices, while transistors are CURRENT controlled devices. The gate in a FET is very much like the grid in a tube, and since I already understood tubes, and transconductance, I had no trouble designing with FETs.

FrankC said...

drjim, did you ever work with nuvistors?
Kinda like a tiny valve in a can. Sounds silly, but they could handle voltages that FETs and transistors couldn't.

Graybeard said...

I think "DeForest electron valve", after Lee DeForest who invented the triode, was the original proper name in the UK. They're still called valves in much of the world and valve guitar amplifier returns 511 items on eBay right now and over 5 million on Bing.

I learned tubes as nerdy kid in the 60s. Later learned solid state as a nerdy young adult.

drjim said...

Yes, I did a lot of work with Nuvistors in my earlier days.
VERY good for the RF amp in the front-end of VHF/UHF radios, and pretty much immune to burn-out from overload, unlike a GaAsFET!
Good gain, low noise, and small power demand. I still see new circuits using them for certain applications.
SiGB....ah, yes....Lee DeForest, who never really invented anything himself, but rather appropriated other people's work. During the patent case over who invented the triode, he couldn't even explain how it worked.
And don't forget the "Edison Effect", which could have led to practical rectifiers years earlier if old Tom hadn't considered it a curiosity not worthy of further effort on his part.