Please help identify these items - Videokarma.org TV - Video

ohohyodafarted · #1 01-30-2011, 05:34 PM

Hi Gang,

I am trying to identify these items for a friend. It appears to be some sort of tube substitution device to me, but that is only a guess. It appears that the Army green, 7 pin plug-in device might be intended to plug into where the minature tubes are located.

Both items have the GAP/R code designation so I am assuming they go together.

Have any of you ever seen one of these before?

Never mind........I should have googled it first. It is an op-amp

http://www.computerhistory.org/colle...ssion/X1585.99

Findm-Keepm · #2 01-30-2011, 05:57 PM

If you ever get the chance, read Bob Pease (of National Semiconductor) and his blog-like rants about things. Bob worked for Philbrick back when those two-tube Op-Amps in the first picture were created. His "What's all this stuff about...." series is heavy on humor and electronics theory/application.

Cheers,

Tubejunke · #3 02-01-2011, 11:38 PM

WOW! I never knew they made an Op-Amp with tubes. Seems like a bit of a contradiction in a way, but I guess there was a need for something like a comparator back in the day. I tend to think of op amps as a product of the solid state era.

PaulOF · #4 02-02-2011, 10:58 AM

Vacuum tube op amps were important in the development of electronic analog computers in the early 1940's. Unlike today's, the early ones had a single input and an inverting output rather + and - inputs. The circuit design was complicated by the need for direct coupling and high stability.

In the 1950's Heathkit made a cute little analog computer

with a total of something like 70 tubes. I would love to get my hands on one of them. They come up on ebay once in a while, but are way out of my price range.
Paul

Tubejunke · #5 02-04-2011, 01:37 AM

Wow! Thanks Paul for the neat story! I printed on of the threadstarter's pictures and hurried to show it to my college Asst. Professor thinking that it might be a surprise, but I was wrong. I should have known because I am lucky enough to have a teacher, and mentor of sorts, that is almost ready to retire. In other words, he is not stuck in a box of solid state and digital technology. He, like I, has been interested in what makes electrons move since he was a kid, so that gives him a well rounded and broad spectrum of knowledge that to me is necessary to truly convey not just part of electronics, but as much as time allows the whole thing. Heck, this man used to MAKE his own capacitors to hand build superhetrodyne receivers when he was a kid. Some people are natural born psysicists and engineers; he is one of those people!

Obviously, there is really no need to train people to repair consumer home entertainment devices, much less vintage TVs and radios. It just would not be practical unfortunatly. They are more or less forced to steer students toward industrial control logic and PLC programming, as well as three phase wiring and inductor motor knowledge. I guess my point is that my instuctor is NOT one of these techs that go blank when you show them a tube driven device or a Simpson VOM! We have some old Simpsons at school but they only make it out of the cabinet if I take one out just to look at all of the blank stares that I get when I use it. I guess a Fuke V is pretty nifty, but to me an electronics technician who can not grasp reading a REAL meter is not really educated enough to graduate and possess the credential. Maybe I am just too old fashioned.

That Heathkit would definitely be cool to see all lit up. I bet it would keep a house warm! That decryption of the old op-amp is so backward from what I learned during the many boring hours that I spent studying about comparators, averagers, adders, and voltage followers. For some reason I just don't get to exited about 3-18V chips! I am glad that I had what the young students would call "old school" for a teacher! I would hate to be the future product of electronics programs led my digi-logic nerds! LOL!