Electronic Circuits Assignment

This assignment is about two separate circuit sketches that you have been given by your supervisor to check (analyse), build and test.  You have been asked to give him a brief report with some recommendations on each circuit.

Circuit 1 - Power Supply Development 

Analysis -

You are required to first do some analysis, particularly around range of output voltage achievable with the adjustment range of the potentiometer connected to the LM317 under full 100mA load.

Further analysis is required of the suitability of the major capacitor C1 for the designed power supply load of 100mA at the extremes of the range of the output voltage (as per variable setting).  Do a comparison check for the crossed out value of 100uF.  What does this tell you?

Build & Test -

You need to build the circuit on your prototyping breadboard and take some measurements with a multimeter (DMM).  (Avoid measuring current with your DMM (unless you have a more expensive one that is fuse protected) - rather measure voltage across a resistance and calculate the current I = V/R)  

Attach a pic (or video clip) of your built circuit showing a measurement (existing in your results table) on your connected DMM.

a) Measure the input voltage and output voltage of the power supply circuit, for both extreme settings of the potentiometer AND for output currents of 0mA and 100mA.

b) By either using the lowest AC voltage range on your DMM or by using a capacitor coupled speaker so you can hear it, see if you can detect any ripple (a.c.) voltage on your d.c. output under all the conditions of part a). [Connect a grounded speaker to the PSU output via a series capacitor of about 100uF (watch out for cap polarity! - wear safety glasses).]

c) From your observations in a) and b), what recommendations do you have?  Prove these by performing appropriate tests.

Circuit 2 - Comparator and Logic Circuit

Analysis -

Considering Circuitry of SECTION X:

Scrutinise the circuit and gain and understanding of its intended operation. Do this by identifying the sub-circuit blocks.

By including datasheet information where needed, calculate expected voltages at points A, B and C for the extreme settings of the potentiometer. Also, calculate the voltage from the potentiometer (threshold) at A, at which you expect the comparator's output to change. What role does the switch SW1 play? Determine any expected timing values in the circuit.

Considering Circuitry of SECTION Y:

By looking at the datasheet of the 4017, work out and explain the expected behaviour of this section of circuitry.

Build & Test -

Build the SECTION X circuit on your prototyping breadboard and include building the MONITOR circuit, connecting its input T to SECTION X's output Q. Take the following measurements using your DMM and a timer (smart handheld device?):

(Tip : Use a wire to simulate the switch SW1 and briefly close the "switch" before each measurement.)

[Note - Attach a pic/video clip of your built circuit showing a measurement (existing in your results table) on your connected DMM.]

a) Using the DMM measure the voltages at A, B and C.  Tabulate results to easily compare to your expected values from your analysis.  Also record the threshold voltage at A for when the comparator output changes.

b) By watching the LED in the MONITOR circuit, measure any timing you observe under the various input conditions set by the potentiometer at A. Explain how the switch SW1 effects the circuit's operation.

Build the SECTION Y circuit on your prototyping breadboard.  Disconnect your Q-T connection and connect Q to S and R to T. Set the potentiometer to the minimum. When powered up, briefly close the switch SW1. Then adjust the potentiometer upwards and note what happens to SECTION Y.  Record your observations. How does it compare to your expectations?

Optional ungraded exercise

By inspecting the operation of the circuit block within Section X that includes gates U1a and U1b, you will be able to see that these could be replaced with a 555 circuit.

Design a suitable circuit block to make the exchange such that the overall function of the complete circuit is unaltered.

For this section you are welcome to post your 55 circuit block that would work to the forum.  Building and testing can verify your design.

Attachment:- Assignment Files.rar