ECE 201L Circuit Analysis Laboratory
Lab 6

This lab provides experience with strain gauges and the CD4013 D flip-flop.

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

1. Mount an instrumented metal strip to the workbench. Most of these strips have a strain gage on each side, so that when one strain gauge is in tension the other is in compression when the metal strip is flexed. Measure the the resistance of each strain gauge when the metal strip is in its relaxed, unstressed condition. Observe and report how the resistance of each gauge responsed to flexure stress.

2. Measure the change in resistance as you add weight to the end of the metal strip. Use some hook-up wire to hold washers. You should be able to hang between 8-10 washers to the strip. Remeasure the resistance after removing each weight before adding a new weight to check that the resistance returns to its nominal value. Plot the resistance change for each strain gauge as a function of the number of washers. Ideally you should measure both strain gauges in tension and compression.

   Thanks to Julia Faeth who determined the mass of a typical washer to be 17.85 grams.

3. Build a wheatstone bridge with the two strain gauges in positions R₁ and R₂ (that is either the left side or the right side of the bridge). Measure the bridge voltage a a function of the applied weight.

   

4. Fabricate and test a two-bit ripple counter, using the CD4013 Dual D Flip-Flop in your parts box. See the circuit, shown below. Use a function generator or DAQ clock generator as the clock signal. Show that you can turn both LEDs off at any time using the reset switch. Demonstrate the circuit to the lab assistant.

   

Maintained by John Loomis, last updated 15 February 2010