[GreenKeys] DT600 replacement op amps

[Bruce Gentry]

Philbrick ( and others) also made solid state operational amplifiers 
that were  cube shaped encapsulated modules. I don't think they were 
ICs.  They were used in some industrial and elevator controllers, and 
adapting ICs to replace them is challenging, and in the case of one 
elevator controller, not fully satisfactory.

       Bruce Gentry, KA2IVY


On 7/8/20 10:29 PM, Gil Smith wrote:
> Ahh, the first semiconductor opamp honor goes to the legendary Bob 
> Widlar's designs: uA702 (1964) and the popular-but-fussy uA709 (1965) 
> from Fairchild.
>
> The ancient (and still available) uA741, LM741, which dates to 1968, 
> was super popular since is was very stable and easy to use -- a dual 
> version of the same basic design is the LM1458 and a similar quad is 
> LM348.  Yup, still available.  Some fun facts:
> https://web.stanford.edu/class/archive/ee/ee214/ee214.1042/Handouts/ho15opamp.pdf
>
>
> In the early 1950s, George Philbrick made the K2-W which used two 
> vacuum tubes -- I have one around here somewhere.
> https://www.computerhistory.org/revolution/analog-computers/3/156
>
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