Designing and Testing of a Delay Unit - Research Paper Example

DESIGNING AND TESTING OF A DELAY UNIT of Affiliation] Table of Contents Table of Contents 2 List of Figures 3 List of Tables 3 PART 4: 4 Experiment: Designing and Testing of a Delay Unit 4 Objectives of the Experiment 4 Experimental Theory 4 Experimental Equipment Used 6 Experimental Components 6 Procedure for carrying out the experiment 7 Results and Discussion 8 Discussion of the Findings 9 Reasons why there is change in the frequencies 11 PART 5: 12 System Calibration 12 Objectives of the Experiment 12 The Oscillators 12 Experimental Equipment 12 Experimental Procedure 13 Results and Discussion 14 Discussion of the findings 14 Conclusion 15 References 15 List of Figures Figure 1: VCO circuit example 5 Figure 2: 555 VRO based timer 7 Figure 3: Example of VRO circuit 8 List of Tables Table 1: Voltage table 9 Table 2: R3 against Delay 14 PART 4: Experiment: Designing and Testing of a Delay Unit Objectives of the Experiment The objective of this experiment is to; explore through experimentation the property of 555 chips, design Voltage Controlled Oscillator, and its testing, build a delay unit, which is 555-based, design a trigger circuit, and strengthen an individual’s practical skills Experimental Theory VCO is a module that is used to generate the frequencies that are detectable by the human ear. These frequencies help an individual to effectively tune the pitch source and setting of the pitch. VCO are instruments that operate like the guitar. When their strings are plucked, they generate notes that are specific. The CV of the VCO is generated from the key board. The CV is to alternate the VCO pitch operating on the same way a string of a guitar changes the pitch of the guitar. VCO at the same time acts as converter of voltage to frequency through the variation of its input voltage. The main function of a VCP is to regulate the level of threshold and the trigger of the signal that is applied to the system. The VCC is three times the value of control voltage applied to the pin at the point of supply. This is as a result of the voltage divider that is built internally. The potentiometer can as well be used to supply the voltage to the pin. This external voltage is alternated by adjusting the potentiometer. When the applied voltage is decreased or increased, the capacity discharging time and its charging time either lengthens or shortens. It is therefore, worth noting that when the input voltage is varied, the frequency of the system also changes. The control voltage is supplied to the pin by use of the potentiometer or through the use of a transistor circuit. The figure below shows VCO circuit example ( Bhatt 2012). Figure 1: VCO circuit example The VCO’s main component is the 555 timer, which is first configured to form a multivibrator that is stable before being employed as an oscillator. Astable multivibrator is a timing circuit that has output oscillating between high logics and low logics developing trains of pulses without stopping. One main difference between the two circuits is that the 555 circuit has its pin 5 connected to the external supply voltage which acts as the control voltage pin. The pin is used when adjustment of the threshold voltage is required. The threshold voltage is a voltage that is used to compare the pin 2 and pin 6 voltages by the comparators that are inbuilt in the system. The comparator outputs are used to control the flip flop circuits of the system that are inbuilt which are used to toggle the 555 timer output and finally, adjusting the pin 5 control voltage that eventually varies the frequency where output of the 555 timer toggles at. When the voltage at pin 5 is increased, then oscillating output, frequency decreases too. At the same time when this voltage is decreased, then output frequency of the oscillation increases. Experimental Equipment Used The equipment that were used to carry out the experiment include, Oscilloscope Multi-meter digital equipment DC unit for power supply Breadboard Experimental Components The components used for the experiment include, Light emitting diode Switch LMC555CN Chips 10n, 22n 100μ capacitors Resistors of the following properties 330kΩ, 200k, 5×100k, 2×5.1k, 1k, 82 Figure 2: 555 VRO based timer Procedure for carrying out the experiment Figure 3: Example of VRO circuit Record both the minimum and maximum values of voltage out and V2 Increase RA to 330 kΩ and record the findings Reset the RA to 100 kΩ, this makes RB to change to 330kΩ. Repeat the test and record the findings Set RA to be equal to RB at 100kΩ and reducing the supply voltage to 6 voltage then repeat test 1 Reduce the supply voltage to 3V then repeat test 1 Set Vcc to a voltage of 9 and supplying voltage of 5 to pin 5. Change voltage 5 between the figures 0-8v in variations of 1 voltage each. Finally, record both the maximum and the minimum voltage values. The graph was finally plotted of maximum voltage V2, minimum voltage V2, Maximum voltage Vout and the frequency with respect to V5 Results and Discussion Voltage V Voltage 2 max *10-1 Voltage 2 min *10-1 Voltage out max *10-1 Voltage out freq *10-1 0 0 0 0 0 1 19.6 5206.9mv 95.0 29.3 2 27.2 9606.9mv 95.0 28.4 3 37.2 22.1v 95.0 8883.0 4 46.8 26.9v 95.0 7447.0 5 56.8 32.1v 95.0 6108.0 6 7 8 66.8 76.8 88.0 36.9v 43.4v 44.9v 95.0 95.0 95.0 4823.0 3677.0 2481.0 Table 1: Voltage table Discussion of the Findings When the waveform of the voltage out and the Vc are compared for a NOR gate oscillator, it is noted that the 555 oscillator timer isa square wave and triangular for the NOR gate oscillator waveform. It was again noted that increasing the RA value results into proportionate increase of the waves amplitudes. The output voltage of the experiment increases from 2.8 voltage to 10 voltage in a proportional manner. When RA is set to 100 kΩ and setting RB to 330 kΩ. It is noted that the duration for Vout decreases from a value of 2.98 ms to a value of 1.386 ms and Vout remains barely constant. Setting RA being equal to RB at 100kΩ and reducing the supply voltage to 6 V, it is noted that the possible Maximum voltage equals 7 V and the possible minimum voltage equals -200mV The following deductions can be made based on the experiments V2 – Vcc maximum is inversely proportional to v2 V2 – Vcc min is directly proportional to V2 Vout - Vcc max is directly proportional to voltage out. Experimental Graphs Reasons why there is change in the frequencies The frequency of the system changes because change in voltage results into change of the circuit impedances and eventual change in the capacitance of the system (Parton 1998). As was discussed earlier, the frequency is inversely proportional to the systems capacitance which can be illustrated as below = 1/ (1.386R2*C). PART 5: System Calibration Objectives of the Experiment The objectives of this section can be summarized as below; To interface the delay unit and the amplifier To interface the oscillators To calibrate the experimental system To strengthen an individual’s practical skills To exercise the experimental theory The Oscillators An oscillator is a device that generates electronic signals and the waveforms, which can be sin waveforms or Times Square waveforms. The oscillators help in the conversion of direct current from AC signals from the electronic devices. Some known examples of oscillator signals include radios and televisions signals, and signals from the computer clock (Parton 1998). Experimental Equipment The equipment used is Breadboard, which has the following components, 9V battery power supply Screwdriver DC Power Supply Unit Oscilloscope Digital Multi-Meter The Experimental Components Include, , Capacitors of 33µ, Potentiometer with the following characteristic 50k Multi-position switch Resistors of the following properties 10k and 300k Linear Carbon, Experimental Procedure Connect the delay unit to the oscillator as illustrated in the figure below Connect the potentiometer as illustrated in the figure and adjust the delay to 60 seconds for the R3, which is at 620kΩ. Replace the power supply with a battery of 9 voltage and observations recorded. Results and Discussion Delay (min) 0.5 1 2 3 4 5 R3 *101 31 62 124 186 248 310 Table 2: R3 against Delay Discussion of the findings Quention1 In order to disable the NOR gate illustrated above, state whether it is necessary for a control signal to be high or whether it needs to be low. The control signal is recommended to be high for the purpose of disabling Quention 2 Calculate the delay unit output for (pin 3 of 555) before it reaches the required delay. Vout=9 Voltage Quention 3 Identify the function of C5 The C5 capacitor helps to ensure that the system’s power is not lost since the system is charged and discharged at various intervals. Quention 4 Why is it necessary to use 2 switches for example using S1 and S2? S2 is used as a safety switch and it protects the components where there is malfunctioning while S1 is used in switching the system on and off depending on the capacitor’s status. Conclusion The VCO was designed and was finally tested using varied experimental procedures. Observations were then made on how various components respond to one another when various parameters are changed. The experimental comparisons indicated that 555 timer waveforms are rectangular in nature while the waveforms for the NOR gate oscillators were seen to be triangular in nature. References Professor Barry Parton 1998, Fundamentals of Digital Electronics, National Instrument Corporation Read More