Introduction
You are required to design two differential amplifier circuits which will convert input signals produced by a sensor in the ranges given below to the required output ranges.
a) Input range 0-1.Y volts to output range 0-10 volts
b) Input range 0-9.Z volts to output range 1-5 volts
Values Y and Z are based on the last two digits of your student number, so if for example, your student number was 123456789 then the required input ranges would be 0 – 1.8 V and 0 – 9.9 V respectively.
The last two digits: 53
Your task is to: –
1. design each circuit, documenting all design calculations.
2. configure simulations of each circuit, using these to verify and demonstrate the correct operation of your circuits.
3. identify practical components which could be used in the manufacture of each circuit, including realistic component values and commercially available electronic devices.
4. produce a full parts list and sample costings.
5. write a brief lab report containing evidence of completion of all tasks above, plus a discussion of your main findings.
Marking Scheme
a) Circuit design and calculations (20 marks)
b) Verification of correct operation – e.g. simulation (20 marks)
c) Component identification, parts list and costing (20 marks)
d) Written report (20 marks)
e) Discussion of findings (20 marks)
Hints and Tips
The differential amplifier circuit is discussed in Week 5 notes. There are worked examples similar to those given above in notes from Weeks 5 and 6.
The output voltage of the above differential amplifier is given by: –
𝑉 = 𝑅2 (𝑉 − 𝑉 )
𝑂𝑢𝑡 𝑅1 2 1
A recommended Proteus test circuit is given below, which you will need to create.
Notes
1) Key component names in the above simulation are “RES” – generic resistor and “OPAMP” – generic opamp. DC voltmeters are available from the Virtual Instruments section of the toolbar at the left side of the screen. Similarly, Power and Ground connectors are available from the Terminals section of the toolbar, at the left.
2) Proteus does not allow multiple components with the same name, hence the use of R1A, R1B, R2A and R2B in place of R1 and R2 respectively.
3) Input voltages V1 and V2 may be inputted in various ways. Power pins have been used in the above example. The voltage is set by entering the voltage as a text string. Examples include “+12V”, “-1V”, “+0V” (a leading plus or minus is always needed).