Mini Project Fall 2023

You and your lab partner are to design a circuit for measuring resistor values.

Your circuit should have two input terminals where you connect the resistor to be

tested, and should produce an output voltage that is numerically equal to the resistor

value in KQ. For example, a 2.5k resistor would produce an output voltage of 2.5

volts. Your circuit must work for any resistance up to 5 KQ and produce a result that is

accurate to within 5% of the resistor value you measure using a DMM. For resistors

greater than 5k your circuit should light an LED, indicating "over range".

When an over-range is encountered, the user should have the option of throwing

a switch or, equivalently, changing one wire connection (not both ends of a wire!) so

that the measurement circuit can measure resistors up to 50k with an output voltage

that is numerically equal to the resistor value in k divided by ten. For example, a 25k

resistor would produce an output voltage of 2.5 volts. Again, resistors greater than

50k should cause an LED to light.

Scoring

The maximum score for this lab is the same as the others, ten points. The design itself

is worth eight points, and the lab report is worth two. To receive the full eight points,

your circuit must meet these additional requirements:

- Use only one power supply. Since our supplies are dual or even triple supplies, this

means you could use +/- 9 volts if you needed it for something...

- Circuit must not draw more than 50 mA

- Use ten or fewer components, not including the wires of course.

Procedure

Before coming to the lab, design your circuit. When you arrive, show your schematic to

the TA, then build it. Testing may show that you need to modify your original design -

that's fine. Continue modifying and testing until it works. After verifying operation,

demonstrate your circuit to the TA.

Lab Report

In your lab report include (a) your final schematic, (b) an explanation of the function of

each component, and (c) comparison measurements using a DMM that show that your

circuit is accurate to within 5%.