automatic Wheatstone bridge ?

[Larry_Morgan]

You can accomplish the "adjustable" wheatstone bridge by a few other ways, also.

One is to use a transconductane amplifier in a voltage controlled resistor config. 

Another is to use a mosfet as a variable resistor. 

So, is this harmonic changing? If not, why not just use a notch filter?

Message Edited by Larry Morgan on 06-16-2009 04:55 PM

[nitad54448]

hi

i don't know how to make the "transconductance.." etc; can you give some references ?

(the frequency does change, it is selected by the user)

thanks

[Larry_Morgan]

LM13700

The LM13700 operational transconductance amplifier datasheet has some application notes that

give some info on building a voltage controlled resistor.

Just wondering, have you done much research to see if the adjustable bridge is the ideal

solution to your problem? There's a good probability that you can dig up an adjustable

filter, or at least a schematic for one that may be simpler to make.

Message Edited by Larry Morgan on 06-17-2009 11:19 AM