[Laser] OPT-101 vs PIN diode

[F1AVYopto at aol.com]

Dans un e-mail daté du 14/12/2006 15:16:46 Paris, Madrid,  
skavanagh73 at yahoo.ca a écrit :


>That is a very interesting circuit.  Have you tried it

No Steve
I  never tried it.
I only use PGP front-ends without gate resistor to detect  ultra low light 
flux.
I never found a more sensitive photo detector for  VLF light modulation.
With low capacitance PN or PIN photodiodes the  bandwidth seems quite 
sufficient for audio voice modulation.
The real PGP  bandwidth effect is a great talking subject!
Because the 1/F FET extra noise,  the best S/N frequency point could be out 
the -3 dB response limit  point.
Because the very low floating photodiode voltage, its internal  capacitance 
is not linear and could give a parametric effect.
The complete  spice model of the PGP front end may be not easy to build...
To cover at  least 1 km in the daytime as well as at night, with a low power 
laser spread to  a wide beam width with an OPT-101 it seems to me the feed 
back Rf  choice should be done after a real field test. The RX lens size  fitted 
in front of the OPT201 is determinant.73
Yves  F1AVY
http://pageperso.aol.fr/YvesF1AVY/