ECE 201L Circuit Analysis Laboratory
Lab 4

This lab provides experience with the Wheatstone bridge, quad NAND gates, and the data acquistion board

Attachment: lab4.zip.

Do the following exercises. Report your results by editing the attached Word document and submitting it in Isidore. Submit one report per group.

  1. See page 55 of your textbook for a description of a Wheatstone bridge. Construct a bridge using your photoresistor and fixed 10KΩ resistor in one arm and a 10KΩ pot / fixed 10KΩ resistor in the other. The exact value of the fixed resistors is not critical. Use your handheld multimeter to measure the bridge voltage. With the photocell looking at the room lights, adjust the bridge potentiometer to balance the bridge (zero voltage). Note that the bridge voltage changes with the light level. If necessary, redesign the bridge so that the bridge voltage increases in the light and decreases in th dark by changing the polarity of either the voltage source or the bridge output.

  2. Now connect the bridge output to an analog input port. Use your hand to shade the sensor. Capture a typical set of data.

    You can use aidata.m, or the sequence of commands: 

    AI_init; % initializes analog input system
AI_setup % sets analog input properties
AI_takedata % acquires and plots one set of data (repeat as desired)
daqstop % closes data acquisition objects

  3. Run the MATLAB data acquistion toolbox softscope. See my example script runscope.m

  4. Let the photocell look at our strobe light. Capture some data and use it to determine the strobe rate.

  5. Find a 4011 Quad NAND chip in your parts box. The pin diagram for this chip is reproduced below.

    Remember to connect power (5 V - pin30 - to pin 14) and ground (GND - pin29 - to pin 7).

  6. Connect one of the NAND gates as shown below.

    Connect A to Port A0 (pin 21), B to Port A1 (pin 22), and F to Port B0 (pin 32). Run diotruth.m, publish the results, and paste the resulting truth table in your report.

  7. Connect two of the NAND gates as shown below. The inverter is obtained by connecting the two inputs of a NAND gate together and also to the input signal.

    Connect the input and output to the DAQ as before, and obtain the truth table.

  8. Now connect three NAND gates as shown below. Obtain the truth table, and identify the resulting gate.

  9. Now connect four NAND gates as shown below. Connect C to A2 (pin23). Change diotruth.m for three variablss (set N = 3) and obtain the truth table.

Data Acquisition Board Pinout

Maintained by John Loomis, last updated 22 September 2009