3 Project- automatic fan controller Operational Amplifier
4 What is Operational Amplifier? Operational Amplifier is an electronic devices which amplifies small ac or dc signal and perform basic operation as addition, subtraction multiplication and so on.Fig. Operational amplifier (LM741)
5 Operational Amplifier Op Amp has 2 inputsVoltage OutputInverting Input+V_Vin1V out+V in2-VNon-Inverting InputInverting Input- the input where output will change to the opposite sign.Non-Inverting Input- the input where output will not change to the opposite sign.
6 Operational Amplifier Op Amp has voltage supply, +V and -VPositive (+) supply voltage+V_Vin1V out+V in2-VNegative (-) supply voltage
7 Operational Amplifier OP-AMP is an IC or Integrated Circuit made of many components
8 Characteristic of Operational amplifier……. High input impedanceOutput impedance is zeroOpen loop gain is high (10,000x)
9 What is the use of Operational Amplifier? Operational Amplifier -amplifies small AC or DC Signal.Operational Amplifier can also do basic operation : add, subtract, multiply (amplify) etc.
10 + +V _ Vin1 V out V in2 -V V out = A x (Vin2 – Vin1) Gain (A) = V out Open Loop Gain = 100,000 x
11 Op Amp as Comparator. Op Amp compares Vin1 and Vin2: If Vin 2 > Vin1 therefore: V out = +VIf Vin1 > Vin V out = -V
12 Op Amp as Comparator.Op Amp compares Vin1 and Vin2:If Vin 2 > Vin therefore: V out = +VIf Vin1 > Vin V out = -VExample: The +V= 15V and; If Vin1= 4mV and –V = -15V Vin2 = 6 mVTherefore: Vin2 > Vin So, Vout= 15V
13 Project- automatic fan controller Operational Amplifier
14 Pin Number or Configuration Fig. LM 311 Op Amp ICFig. LM 741 Op Amp IC
15 Pin Number or Configuration Pin Configuration is the assignment of Pin number with the corresponding use.
16 Pin Number or Configuration Pin 1 and Pin 5: Offset null input; used to remove the Offset voltage (a small DC voltage that exists at the op-amp inputs that will contribute to a significant error at the output).Pin 2: Inverting input (-VIN); signals at this pin will be inverted at output Pin 6.Pin 3: Non-inverting input (+VIN); signals at pin 3 will be processed without inversion.Pin 4: Negative power supply terminal (-VCC).Pin 6: Output (VOUT) of the Op-AmpPin 8: No connection (N\C), it is just there to make it a standard 8-pin package
17 Other uses of Op Amp. Inverting Amplifier Non inverting amplifier Summing AmplifierDifferential amplifierVoltage followerIntegratorDifferentiator
18 Revision Question________________is an electronic devices which amplifies small ac or dc signal and perform basic operation as addition, subtraction multiplication and so on.________________- input of Op Amp where the output is changed to opposite sign.________________ the open loop gain of Op Amp.________________ use of an Op Amp with no feedback. where it compares Vin2 and Vin2.________________ the arrangement of Pin of an integrated circuit of IC.________________ is the Pin number of the output of a LM741 operational amplifier.
26 What is NTC?NTC is a Thermistor or Thermal Resistor that converts Temperature to Change in Resistance.It has two (2) types; NTC and PTCNTC – Negative Temperature Coefficient. As temp increses, resistance Decrease.PTC – Positive Temperature Coefficient. As tempincrease, resistance increases.Resistance , ohmResistance , ohmTemperature, deg CTemperature, deg CNTCPTC
27 Voltage Divider… VB = Vcc x RNTC . R1 + RNTC Vcc The voltage VC changes the resistance of the Thermistor changes.ABCR1VB = Vcc x RNTC .R1 + RNTC
28 Revision Question________________ a circuit that divided the voltage proportionally with the value of resistors connected in series._______________ a thermal resistor that converts temperature in change in resistance._______________ use of an Op Amp with no feedback. where it compares Vin2 and Vin2.________________ the arrangement of Pin of an integrated circuit of IC.
29 Voltage Divider… Vc = Vcc x RNTC . R1 + RNTC Vcc A R1 B C If R1 = 10,000RNTC = 30 deg CVB = 10V x ( 10,000/20,000)VB = 5V
30 Voltage Divider… Vcc = 10V If R1 = 10,000 A RNTC = 10,000 @ 30 deg C BCR1If R1 = 10,000RNTC = 30 deg CVB = 10V x ( 10,000/20,000)VB = 5VIf RNTC = 50 deg CVB = 10V x (8,000/ 18,000)VB = 4.44 V
34 Potentiometer.Vcc= 10VABCVSo, in the middle VBC = 5V
35 I will combine potentiometer circuit and the Voltage divider circuit with NTC VccABCR1BCAVcc= 10V
36 So, this 2 circuit is the input to the operational amplifier
37 So, this 2 circuit is the input to the operational amplifier IN THIS FIGURE ONLYSo, if Vin2 > Vin3 = Vout = +12V
38 So, if Vin2 > Vin3 = Vout = +12V Voltage OutputIN THIS FIGURE ONLYSo, if Vin2 > Vin3 = Vout = +12VThe Vout = +12V will activate the Driver Transistors
39 What is Transistor? BJT?Transistor is derived from the combination of two words, “Transfer-Resistance”. It means that it is a device, which transfers a low resistance into a circuit having high resistanceBJT - is a three-terminal semiconductor device, whose operation depends upon the flow of electric charge carriers within the solid.
41 Transistor ID. Low Power Small Packages Medium Power Medium Packages High Powerbig Packages
42 Transistor Action… Its emitter is its negative terminal. The base is 0.7V (or slightly more) positive of its emitterThe base is 0.7V (or slightly more) positive of its emitterThe base is 0.7V (or slightly more) positive of its emitterTransistor Action…Its emitter is its negative terminal.The collector is several volts positive of its emitter.The base is 0.7V (or slightly more) positive of its emitter
43 Use of Transistor. Transistor is used as: Switch Amplifier. Will Turn ON the TransistorSmall Base Current
44 Transistor as switch… When switch is closed: Small base current is applied to the base.LED B is DIM (small current)Transistor is turned ON allowing emitter-collector current which is bigger.LED C will have a bright light (big current)
45 So, if Vin2 > Vin3 = Vout = +12V Voltage OutputIN THIS FIGURE ONLYSo, if Vin2 > Vin3 = Vout = +12VThe Vout = +12V will activate the Driver Transistors
46 R BaseSo if the output of the OP Amp is Hi, it will provide base current to the transistor making it ON thus Energizing the Relay.
47 What is a Relay?Relay – an electrically operated switch. It is made of coil and set of contacts, NO NC.
48 AC power SupplySmall CurrentMed CurrentR BaseBig current
49 ConclusionWe Learned About:Application of Semiconductor Devices: transistor diode, etc..Learned the operation of transistorWE learn operational amplifier and it uses.We make use of LED as indicator of current.