Chris,
Just curious, why an incandescent bulb and not an LED?  Also, 
that's a pretty large area photodiode.  Trying to keep the noise 
down?
 
Thanks,
Jack Ivey
 
 -----Original Message-----
From: ChrisAtUpw@....... [mailto:ChrisAtUpw@........
Sent: Thursday, November 22, 2001 5:08 PM
To: psn-l@..............
Subject: Re: Publication on the Web



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 








Chris,
Just 
curious, why an incandescent bulb and not an LED?  Also, 

that's 
a pretty large area photodiode.  Trying to keep 
the noise 
down?
 
Thanks,
Jack Ivey
 
 -----Original Message-----
From: 
ChrisAtUpw@....... [mailto:ChrisAtUpw@........
Sent: Thursday, 
November 22, 2001 5:08 PM
To: psn-l@..............
Subject: 
Re: Publication on the Web


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