Another weird item from my clear-out - tiny thermionic valves !

[CatalinaWOW]

Thanks for a trip down memory lane. 

I always thought that the term "acorn tubes" was reserved for the glass envelope tubes a little over a centimeter in diameter which where sealed around radial pins on a shelf around the lower half of the tube.  Nuvistors were a still smaller package, originally proprietary to RCA.  While Nuvistors were used in some high end gear, they also made it into television receivers during some of the last gasps of thermionics in that market.  Probably reached their highest volume there.  Thermionics made it well into the 1970s as the high voltage rectifier.

[wkb]

When I was a kid I remember seeing inside my Aunt Martha's hearing aid. The electronics box was about the size of a packet of twenty cigarettes and it had two or three tiny valves in it, each about 20mm long and wire ended rather than fitted into a socket. Most of the box was filled by the battery which must have been at least 40V.

Yep, and I even have a couple of these tiny valves somehere (...). A quick dig in the garage proved fruitless but I'll try to find them.  And post a photo here of course.

[T3sl4co1l]

I'd be rather interested in those 7077s, though by the sound of it I'm too late already.

Tim

[med6753]

Thanks for a trip down memory lane. 

I always thought that the term "acorn tubes" was reserved for the glass envelope tubes a little over a centimeter in diameter which where sealed around radial pins on a shelf around the lower half of the tube.  Nuvistors were a still smaller package, originally proprietary to RCA.  While Nuvistors were used in some high end gear, they also made it into television receivers during some of the last gasps of thermionics in that market.  Probably reached their highest volume there.  Thermionics made it well into the 1970s as the high voltage rectifier.

Here is a description of acorn tubes:

https://en.wikipedia.org/wiki/Acorn_tube

[Fraser]

I stand corrected on the Acorn valves. I never delved into their exact shape before.

Fraser

[richfiles]

Boy, those sure are beautiful little things! 
Makes you wonder where thermionic tech might have eventually led, had the transistor and it's derivatives not displaced it.

[Ian.M]

Probably to low voltage cold cathode ceramic cased hybrids with similar complexity and size to a SSI IC in a CERDIP package