M
Marco Trapanese
- Jan 1, 1970
- 0
Hello,
some time ago I opened a thread about the AD698. I'm still in trouble. I
recall you the schematic:
http://img685.imageshack.us/img685/382/lvdt.png
and the circuit specifications:
Vs = 24V
Vexc = 10 Vpk-pk (tried also lower voltage)
fexc = 5 kHz
BW <= 10 Hz
Vout = 0-5V (2.5V at null)
I use a series opposed lvdt with a sensitivity of 1.366 mV/V/mil and a
range of ±500 mil.
Here some pictures of the behavior of the board.
Exciting wave:
http://img710.imageshack.us/img710/4100/img106xy.jpg
http://img338.imageshack.us/img338/6969/img107wo.jpg
Secondary wave (output of lvdt):
http://img580.imageshack.us/img580/4154/img108v.jpg
It is at maximum displacement. At null reach zero volt.
Afilter signal:
http://img827.imageshack.us/img827/2142/img109gb.jpg
Bfilter signal:
http://img9.imageshack.us/img9/4858/img110fl.jpg
Output signal:
http://img17.imageshack.us/img17/6429/img111on.jpg
This is centered on about 2.6V (from resistor divider on sig ref) but it
remain fixed moving the lvdt position. Instead I want it changes between
0 and 5V.
I tried also to place a resistor across the demodulator input (as
suggested in the previous thread) with no effect.
I have no idea how to find the cause of the problem
Marco
some time ago I opened a thread about the AD698. I'm still in trouble. I
recall you the schematic:
http://img685.imageshack.us/img685/382/lvdt.png
and the circuit specifications:
Vs = 24V
Vexc = 10 Vpk-pk (tried also lower voltage)
fexc = 5 kHz
BW <= 10 Hz
Vout = 0-5V (2.5V at null)
I use a series opposed lvdt with a sensitivity of 1.366 mV/V/mil and a
range of ±500 mil.
Here some pictures of the behavior of the board.
Exciting wave:
http://img710.imageshack.us/img710/4100/img106xy.jpg
http://img338.imageshack.us/img338/6969/img107wo.jpg
Secondary wave (output of lvdt):
http://img580.imageshack.us/img580/4154/img108v.jpg
It is at maximum displacement. At null reach zero volt.
Afilter signal:
http://img827.imageshack.us/img827/2142/img109gb.jpg
Bfilter signal:
http://img9.imageshack.us/img9/4858/img110fl.jpg
Output signal:
http://img17.imageshack.us/img17/6429/img111on.jpg
This is centered on about 2.6V (from resistor divider on sig ref) but it
remain fixed moving the lvdt position. Instead I want it changes between
0 and 5V.
I tried also to place a resistor across the demodulator input (as
suggested in the previous thread) with no effect.
I have no idea how to find the cause of the problem
Marco