Vintage operation amplifier

Thread Starter

jafal

Joined Jul 4, 2017
31
Hi all I have this ic CA3028A metal can how to connect it it's not looks like 741 or other modern iC's

Thanks in advance
 

Ian0

Joined Aug 7, 2020
9,667
Pin 3 goes to the negative supply. Pin 7 goes to ground, so that it sets the constant current in the long-tailed pair.
Pins 1 and 5 are the inputs.
 

AnalogKid

Joined Aug 1, 2013
10,986
I have this ic CA3028A metal can how to connect it it's not looks like 741 or other modern iC's
That's because it is not. That part is only the "front end" of a traditional opamp circuit. Almost all operational amplifiers have a differential pair at the input, often powered through a current source. That is what the 3028 is. It does not have the next two opamp sections, a voltage amplifier and an output stage. To make a complete amplifier, you have to design those sections with discrete components.

This part goes back to the days when complete IC opamps did not have very good DC performance or bandwidth, and the 741 is a good example. RCA had a bunch of transistor function chips like this one. Because two transistors on an IC die are extremely well matched in their performance characteristics, and very close together so their changes with temperature tracked very precisely, it saved designers from having to hand-select transistors to match their DC characteristics.

Waaaay back, I used this part as an RF amplifier in a video tape machine rebuild. Here is the app note referenced in the datasheet:

https://catedra.ing.unlp.edu.ar/electrotecnia/electronicos2/download/Notas/an5337.pdf

ak
 

Papabravo

Joined Feb 24, 2006
21,158
That's because it is not. That part is only the "front end" of a traditional opamp circuit. Almost all operational amplifiers have a differential pair at the input, often powered through a current source. That is what the 3028 is. It does not have the next two opamp sections, a voltage amplifier and an output stage. To make a complete amplifier, you have to design those sections with discrete components.

This part goes back to the days when complete IC opamps did not have very good DC performance or bandwidth, and the 741 is a good example. RCA had a bunch of transistor function chips like this one. Because two transistors on an IC die are extremely well matched in their performance characteristics, and very close together so their changes with temperature tracked very precisely, it saved designers from having to hand-select transistors to match their DC characteristics.

Waaaay back, I used this part as an RF amplifier in a video tape machine rebuild. Here is the app note referenced in the datasheet:

https://catedra.ing.unlp.edu.ar/electrotecnia/electronicos2/download/Notas/an5337.pdf

ak
The TS has been absent for over a month. He might have ghosted us.
 
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