Build a Electronic Transistor Turns Op Amp On or Off Circuit Diagram.
In this circuit When transistor Q1 is switched off, the circuit behaves
as a voltage follower. By applying a positive voltage to the emitter of
Q1 via a 10 KOhmhm resistor, the transistor is made to turn on and go
into saturation. Thus, the lower end of R4 is connected to ground.
Electronic Transistor Turns Op Amp On or Off Circuit Diagram
The circuit has not changed into that of a differential amplifier,
except that the voltage difference is always 0 V. As long as the
resistor ratios in the two branches around the op amp are in the same
ratio, the output should be zero. A 47-KOhm resistor is used to null out
any ratio errors so that the off attenuation is more than 60 dB. The
high common-mode rejection ratio of a 741 enables this large attenuation
to be obtained.
