| Op-amp variable gain amplifier |
Op-amp variable gain amplifier
a variable gain circuit using an operational amplifier
A useful variable gain and sign amplifier can be constructed
using a single variable gain amplifier. The circuit uses a single operational
amplifier, two resistors and a variable resistor.
Variable gain operational amplifier circuit
Using this circuit the gain can be calculated from the
formula below. In this the variable "a" represents the percentage of travel of
the potentiometer, and it varies between "0" and "1". It is also worth noting
that the input impedance is practically independent of the position of the
potentiometer, and hence the gain
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