In a message dated 21/11/2001, jimesler@.......... writes:

>  I've been playing around with a Texas Instruments TSL230 chip - 
> http://www.taosinc.com/pdf/tsl230.pdf  which is a light to frequency 
> converter - which if you have enough time between samples may possibly be 
> used as a photon counter?

Dear Jim Esler,

       I looked at the TSL230 data sheet and I am doubtful if it could give 
the very high resolution required for a seismometer. If you want to try a 
photo detector system, I suggest that you experiment with a couple of the 7.5 
sqmm photodiodes type VTD34 from www.newark.com. Illuminate them from a 
common source, preferably a filament lamp run at about 3/4 the rated voltage, 
to give a half shaded current of 50 to 100 micro A each.  

       Regards,

       Chris Chapman
In a message dated 21/11/2001, jimesler@.......... writes:



 I've 
been playing around with a Texas Instruments TSL230 chip - http://www.taosinc.c
om/pdf/tsl230.pdf  which is a light to frequency converter - which if you have enough time between samples may possibl
y be used as a photon counter?




Dear Jim Esler,



       I looked at the TSL230 data sheet and I am doubtful if it could give the very high res
olution required for a seismometer. If you want to try a photo detector system, I suggest that you experiment with a couple of 
the 7.5 sqmm photodiodes type VTD34 from www.newark.com. Illuminate them from a common source, preferably a filament lamp run a
t about 3/4 the rated voltage, to give a half shaded current of 50 to 100 micro A each.  



       Regards,



       Chris Chapman