This lab is intended for interior decorators that have clip to look into filter theory as shown in the college communications text edition. The pre-engineers are traveling to construct a Narrow Band Pass Filter to compare theory with designed circuit behaviour. By making this the pupils will be able to better understand the theory based computations and construct difficult wired circuits. When planing a band-pass filter. the parametric quantities of involvement are the addition at the mid frequence and the quality factor which represents the quality of the band-pass filter. A band-pass filter is one that allows a narrow scope of frequences around a centre frequence to go through with minimal fading but rejects frequences above or below this scope. The pupils built a narrow band-pass filter which is a reasonably respected filter because it holds a narrow bandwidth.
* Capacitors: ( 2 ) . 001µF
* Resistors: ( 2 ) 390? . ( 1 ) 7. 3k? ( 1 ) 20?
* Amplifier: 741 Op Amp
* LPS-151 DC Tracking Power Supply
* 2532 Digital Storage Oscilloscope
* Fluke Digital Multi-meter
* Leader LFG 1300S Functional Generator
The technology squad built the circuit shown in figure 1. Keep in head ; utilize the minimum sum of wiring to avoid stray electrical capacity which by and large happens at high frequence. We used a LN-741 with two District of Columbias 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 figure 7 pin of the op-amp. The negative power supply was connected to the figure 4 pin of the op-amp. It is really of import that the circuit be wired right. We had our teacher verify the circuit was wired right. The ac power supply was set to about 10V and connected to the R1 obstructionist. Second. we adjust the signal generator to 19kHz. Once the circuit was to the full connected and working decently. we verified at which frequency the bandwidth picks up and drops out. In order to cognize that the circuit is working decently. the end product electromotive force should read about 6 to 8 Vs. The electromotive force ( sine moving ridge ) should read the full CRO screen. utilizing the *1 puting on the CRO prongs.
The pre-engineering squad built the band-pass filter shown in figure 1 on page 2. There were some wiring issues at the beginning of the lab. but with a small test and mistake the squad was able to have an end product that slightly resembled the features of a narrow width band-pass filter. The information sheet which showed the addition to frequency ratio was really similar to the addition to frequency ratio the squad received in the information they found utilizing the 741 op A. Figure 3 is non as steep of incline or cut-off point as figure. Figure 3 shows end product electromotive force compared to frequency and Figure 2 compares addition and frequence. Keeping in head Figure 2 is the ideal graph. the op-amp used has certain per centum of mistake which does do some computations differences and mistakes.
The resonating frequence is where the circuit worked the best. A good illustration of this is in figure 4. The resonating frequence was about 7. 8khz. This frequence was half of the expected resonating frequence. The resonating frequence was intendted to be 19kHz. The ground the frequence was half of the intended frequence is because we could non set the input electromotive force any higher to the ac amplitude. Furthermore the CRO would non adjustable to read the exact end product electromotive force doing at that place to be jobs in ciphering the right electromotive force addition. However the consequences were non every bit precisely as intense pated. but the technology squad was able to acquire a response with the lab equipment offered.
Jr. Frenzel. Louis. Principles of Electronic Communications: Chapter 2. New York: Culverwell. 2008. Print
Sabin. William E. Narrow Band-Pass Filters for HF: Band-pass filters can be critical constituents in competitory Stationss. This apparatus may assist set your station on the map. Wyoming: QEX. 2000. print.