[sdiy] Discrete Op Amps

[Gordonjcp]

On Sun, Apr 09, 2017 at 11:27:48AM +0200, Michael Zacherl wrote:
> 
> On 8.Apr 2017, at 13:27 , Gordonjcp <gordonjcp at gjcp.net> wrote:
> 
> > Under all possible circumstances - even preamps for the golden-eared audiophools - discrete opamps will be outperformed in every respect by even the cheapest shittiest IC.
> 
> µA741 ?  ;)
> 
> (also got a 709 here ;)  
> 
> 
> m. (teasing)

Yup!  The circuit I linked to does actually work as an opamp and works surprisingly well - there's not a lot of gain and it takes about a quarter of an amp to run, but it works.  You can think of it as being analogous to a toy steam engine compared to a modern car engine, in that it's simple enough to see what's going on and it'll make some of the aspects of real-world systems a little less surprising.

I remember my Engineering Applications tutor at university passing round a discrete opamp module from some old piece of implementation, about the size of a paperback book.  It looked rather like the semi-open frame power supplies that folk use in their modulars, all chock full of trimmers and germanium trannies.

-- 
Gordonjcp MM0YEQ