# Narrow Band Pass Filter

Topics: RLC circuit, Band-pass filter, Passband Pages: 4 (820 words) Published: February 25, 2013
I. Introduction:
This lab is intended for designers that have time to check filter theory as shown in the college communications textbook. The pre-engineers are going to build a Narrow Band Pass Filter to compare theory with designed circuit behavior. By doing this the students will be able to better understand the theory based calculations and build hard wired circuits. When designing a band-pass filter, the parameters of interest are the gain at the mid frequency and the quality factor which represents the quality of the band-pass filter. A band-pass filter is one that allows a narrow range of frequencies around a center frequency to pass with minimum attenuation but rejects frequencies above or below this range. The students built a narrow band-pass filter which is a fairly respected filter because it holds a narrow bandwidth. II. Materials:

* Capacitors: (2) .001µF
* Resistors: (2) 390Ω, (1) 7.3kΩ (1) 20Ω
* Amplifier: 741 Op Amp
* LPS-151 DC Tracking Power Supply
* 2532 Digital Storage Oscilloscope
* Fluke Digital Multi-meter
* Leader LFG 1300S Functional Generator
III. Procedure:
The engineering team built the circuit shown in figure 1. Keep in mind; use the minimal amount of wiring to avoid stray capacitance which generally happens at high frequency. We used a LN-741 with two dc power supplies and one ac power supply. The dc power supplies consisted of a positive power supply and a negative power supply set at 12V. Once the circuit were built the positive power supply was connected to the number 7 pin of the op-amp. The negative power supply was connected to the number 4 pin of the op-amp. It is very important that the circuit be wired correctly. We had our instructor verify the circuit was wired correctly. The ac power supply was set to approximately 10V and connected to the R1 resister. Secondly, we adjust the signal generator to 19kHz. Once the circuit was fully connected and working properly, we verified at...