Substitute of FET in the circuit below

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rajaram04

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Hello sir
I ve got a link related stereo to mono convertor (active type) which is here as follows

https://ahd1at.blogspot.in/2012/08/stereo-to-mono-converter-based-on-fet.html



In the above circuit what can we implant in place of the FET (2N3819) at final output ?

Is it possible to place any other type or same is compulsory ?

if yes then what is the substitute for it ? please comment . . . . . . . thanks
 

The 2N3819 Jfet has an IDSS of from 2mA to 20mA.
A 2N5458 has an IDSS of from 2mA to 9mA and can be used,
a 2N5459 has an IDSS of from 4mA to 16mA and can be used,
a 2N5485 has an IDSS of from 4mA to 10mA and can be used,
and a 2N5486 has an IDSS of from 8mA to 20mA and can be used.
 


You can use a bipolar transistor with additional bias circuit (base voltage divider, coupling capacitor).
 

Probably this option would bring some "complexity", due to be not a simple replacement on PCB, but to require not predicted components.


+++
 

Probably this option would bring some "complexity", due to be not a simple replacement on PCB, but to require not predicted components.
Yes. The original post wasn't quite clear what should be placed instead of 2N3819.

2N3819 is a popular and well available JFET, so I don't see a reason to replace it with a different type. I would probably use BF245C (or BFR30 SMD type), but almost any NJFET can do. If a larger input voltage level should be processed without distortion, higher Vgs,off values are necessary. A BJT emitter follower gives better linearity but higher part count.
 

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