In a message dated 30/05/2005, royb1@........... writes:

Electronic Micrometer, Seismograph, LVDT Transducer Item number:  
6183156631 ends May 5
Handy  device.
Bob



Hi Bob,
 
    Ends June 5th!
 
    Umm? This looks like the type of LVDT which has an  integral transistor 
square wave oscillator / diode rectifier demodulator. On the  types that I have 
used, there was some feedthrough of the drive signal and the  output / 
sensitivity did drift a bit with temperature. +/-0.1" is on the low end  of the 
commercial range. I would expect it to be able to measure 1/10 thou OK. I  would 
guess that 1/25 of this or less, 1 micron, would probably be down in  the 
system noise. 
    See _http://www.transtekinc.com/_ (http://www.transtekinc.com/)  for more 
 information.
    For the very high sensitivity low noise detectors  for seismometers, you 
can use a sine wave drive and a FET IC phase sensitive  detector, with an 
AC/AC sensor. 
 
    Regards,
 
    Chris Chapman






In a message dated 30/05/2005, royb1@........... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2> =20
    Electronic Micrometer, Seismograph, LVDT Transducer Item number:=20
  
6183156631 ends May 5
   Handy=20
device.
Bob


Hi Bob,
 
    Ends June 5th!
 
    Umm? This looks like the type of LVDT which has=
 an=20
integral transistor square wave oscillator / diode rectifier demodulator. On=
 the=20
types that I have used, there was some feedthrough of the drive signal and t=
he=20
output / sensitivity did drift a bit with temperature. +/-0.1" is on the low=
 end=20
of the commercial range. I would expect it to be able to measure 1/10 thou O=
K. I=20
would guess that 1/25 of this or less, 1 micron, would probably be down=
 in=20
the system noise. 
    See http://www.transtekinc.com/ fo=
r more=20
information.
    For the very high sensitivity low noise detecto=
rs=20
for seismometers, you can use a sine wave drive and a FET IC phase sensitive=
=20
detector, with an AC/AC sensor. 
 
    Regards,
 
    Chris Chapman