Old techies

[Tom]

There is a 'zero setting' adjustment screw, but it is internal to the meter...

Karl, that takes me back many years (40+) to when I used to calibrate analog instruments. Forgot all about it until I read your post. Strange how a simple comment can bring back lots of great memories (nah, not memories of calibrating stuff, but memories of those times, places and friends).

 

[Karl]

Tom,

Same here! Spent many hours calibrating industrial 'controlling' meters; those with a small metal flag on the pointer that changed the capacitance of the circuit when it passed between two metal plates (the other poles of the capacitor). Of course they had to read the same on all three axes; this was done by adding or removing tiny blobs of rosin from selected points on the movement arm pivot assembly. Current standard was a platinum/platinum 10% rhodium thermocouple, traceable to NBS, in a 5 gallon distilled water ice bath. Needless to say, before doing the calibration the pivot jewels had to be cleaned or replaced, every minute speck of dust removed, and the pivot tension and movement springs adjusted properly. Not fun, but necessary to get FS accuracy of +/- .05mA. Today you just hook up a 20-cent op amp as a differentiator and you've got the same; no, BETTER!, thing.   

 

[Tom]

LOL Karl, I remember when op amps were $20. If you try to explain what a single transistor looked like to some young kid today, they'd ask which planet you came from. Tubes - "what the heck are they?" they'd ask.

 

[Karl]

Tom,

You MUST remember the Raytheon CK722; the first(?) discrete transistor available to the average Joe, sometime back in the early 50's.?? IIRC, they cost about $8 each; not exactly pocket change back then

 

[Tom]

You MUST remember the Raytheon CK722; tback in the early 50's.??

Not quite, Karl  ;D

 

[Ned]

I built a lot of different projects with my CK722.  I bought one as soon as they showed up in the parts store.

 

[Tom]

At that time, I would have probably thought you and Karl were old guys. Some perceptions don't change  ;D

 

[Ned]

Someday you'll be an OF too

 

[AlGriefer]

Or, you can prove that you're a really OF if you know what a 5U4 was and what it did!

I can remember building a count down stopwatch from TTL chips and it taking up a box almost the size of a car radio!

Al

 

[Jeff]

Ah, now I'm beginning to understand!!! ;D ;D ;D ;D

 

[joelmyer]

Or maybe a really really OF if you remember that you once knew what a 5U4 was & did.

 

[Tom]

I guess I qualify as a really OF, but not yet a really really OF.

 

[Just Lou]

You can still buy 5u4's.  In the old NAVY (the one with wooden ships and iron men) we used 5y3's because they were cheaper.  Threw them away by the dozen.  Please don't take me that far back in my memory again.  It's too hard on my old heart. 

 

[AlGriefer]

You can still buy 5u4's.? In the old NAVY (the one with wooden ships and iron men) we used 5y3's because they were cheaper.? Threw them away by the dozen.? Please don't take me that far back in my memory again.? It's too hard on my old heart.?

The first computer I was trained on in the Navy was built shortly after WWI and had no electronics at all, just mechanics and electrics servos.  It was the Mark IA fire control computer and, as I understand it, it was still being used through the 80s.

Al

 

[Just Lou]

Al,
I think you are correct, however, they converted it into an anchor some time in the 70's and decommissioned it in the 80's because it would only sink intermittently.  lol