[Laser] New optical front ends

[F1AVYopto at aol.com]

Steve
The JFET mu amplifier has a very high  gain but it is not very fast, 
typically 20 KHz.
The photodiode time constant  in the FET gate is very slower than 20 KHz so 
this point is not critical in the  optical response.
With a big resistor the voltage gain can reach 500 with  only two FETs !
This old circuit designed in 1943 with tubes and redesigned  with FETs in 
1970 was used for guitar microphones to get a very high gain with  only few 
discrete components.
For me the main advantage from this schematic  is the ability to have the 
input FET at its Idss current so at its lower  noise.
Some theory and info can be found at:  
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm
http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm
http://www.diyitalia.it/index.php?option=com_zoom&Itemid=55&page=view&catid=27
&PageNo=1&key=2&hit=1
73  Yves F1AVY.