Accurate-variable-gain-circuit


Posted on May 26, 2012

The circuit can use any general-purpose, low-offset, low-drift op amp, such as the OP-07. The differential signal from the bridge feeds an amplifier that drives an ordinary, rugged ±50-p.A meter. Near the null point, however, the drastically reduced signal level from the bridge requires very high gain to achieve a high null resolution. To provide the variable-gain feature, the op amp`s feedback path needs a dynamic resistance that increases as the input signal drops.


Accurate-variable-gain-circuit
Click here to download the full size of the above Circuit.

Two common signal diodes, Dl and D2, in an antiparallel configuration in the feedback path supply function for all positive and negative inputs. To stabilize the op amp circuit at high gain, capacitors C3, C5, and C6 reduce response to high frequencies; capacitors Cl and C2 bypass the amplifier"s power supplies.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Voltage Inverter II
Bass-treble, Volume, balance and Loudness control
Bandpass filter
Optoisolator And Optocoupler Interface circuits
uhf antenna amplifier booster
FM Transmitter
LED-Microscope
simple 12db/octave filter
A flat tire warning circuit



Top