Hi all seis experimenters,

     John Lahr has very kindly put my notes on the LVDT precision seismic 
sensor Kit on his Website at: 
http://jjlahr.com/science/psn/chapman/lvdt/

     Th introductory notes now include three close up Webcam photos of the 
sensor and board. Click on any photo to get an enlarged image. 

     The Experimental notes include details of the modifications to reduce 
the sensor noise and to greatly extend the period, with circuit diagrams and 
components lists. I have been able to achieve a resolution of about +/-7 nano 
metres and a sensor movement range of >+/-12 mm with this Kit.

     I am developing additional LVDT applications circuits with inexpensive 
sensors similar to those used by Sean Morrissey on his vertical STM-8 and 
also with capacitative sensor plates. I will publish them in due course. The 
NE5521 LVDT chip seems to be easy to use and to be capable of excellent 
performance. 

     Please also look at my notes on Meredith's Website 
http://geocities.com/meredithlamb/

     Regards, 

     Chris Chapman
Hi all seis experimenters,



     John Lahr has very kindly put my notes on the LVDT precision seismic sensor Kit on his Website at: 

http://jjlahr.com/science/psn/chapman/lvdt/



     Th introductory notes now include three close up Webcam photos of the sensor and board. Click on any photo to get an enlarged image. 



     The Experimental notes include details of the modifications to reduce the sensor noise and to greatly extend the period, with circuit diagrams and components lists. I have been able to achieve a resolution of about +/-7 nano metres and a sensor movement range of >+/-12 mm with this Kit.



     I am developing additional LVDT applications circuits with inexpensive sensors similar to those used by Sean Morrissey on his vertical STM-8 and also with capacitative sensor plates. I will publish them in due course. The NE5521 LVDT chip seems to be easy to use and to be capable of excellent performance. 



     Please also look at my notes on Meredith's Website http://geocities.com/meredithlamb/



     Regards, 



     Chris Chapman