ECE Projects
 
 

 

Electronic Projects

       AudioRF Circuits 
     
      Event Detection Circuits 
         
      Math Function Circuits 
         
      Measurement Circuits 
    
      Motor Control Circuits 
         
      Power Supply Circuits 
         
      Sensing Circuits 
         
      Special Function Circuits 
         
      Switching Circuits 
     
      Timing Circuits 
         
      ToneWave Generators 

Tunable Band Pass Filter Circuit

Figure 1.  Circuit Diagram for a Tunable Band-Pass Filter

This is a circuit that can be tuned to only allow input signals within a certain range of frequencies to pass to the output, hence the name 'tunable band-pass filter'.  All signals with frequencies lower or higher than this range are attenuated (weakened or decreased in level) by this circuit.

The circuit is an active filter that uses a 741 operational amplifier IC configured to pass a narrow band of frequencies ranging from a few hundred hertz to about 3 kHz. This circuit may be used to detect the presence of a tone in this frequency range.  Variable resistor R2 is used to 'tune' the center frequency of this filter.