Dual FET Buffers (was: Re: [sdiy] Kraakdoos line out)

[Scott Gravenhorst]

The two FETs and two resistor method - is this the one Don Tillman
posted a while back?  

An N-FET and a P-FET?  Would this work with MOSFETs?  

(I guess it would - in fact, one could make 2 such buffers from a
4007UB).  Looking at the current source and sink capabilities of the
4007UB, I would say that the transistors are symmetrical.  

What are the conditions under which one would use such a buffer
_without_ the usual feedback resistor?




Metrophage <c0r3dump23 at yahoo.com> wrote:
>
>--- Ian Fritz <ijfritz at earthlink.net> wrote:
>> Are you saying that the added cap and resistors themselves do not
>> hurt the operation, ie there is only a problem when the cable is also
>> connected?
>
>Exactly.
>
>> The next step might be to add an FET source follower between the
>> opamp and  the big cap.  With two FETs and two resistors you can make
>> a high impedance buffer with no offset voltage.  Wouldn't take up
>much 
>> room!
>
>Interesting, I don't recall having read about FET source followers.
>I've only ever used FETs for switching type stuff,I've never put audio
>through them. Something new to learn about!
>
>Thank you for suggesting another interesting idea, Ian!
>CJ
>
>
>	
>		
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