1. Digital Multimeter (DMM) Used to measure the following: Voltage – DC and AC Current – DC and AC Resistance Capacitance Temperature – w/ extra probe Also used to check: Diodes Transistors 1

2. We’ll Use the DMM to Measure Resistance Resistors restrict the flow of current, given a fixed voltage Unit = Ohms, Ω They come in different packages 2

3. Color Code The resistors we’ll test have a color code to identify their resistance and tolerance. 3

4. ColorValueColorValue Black Brown Red Orange Yellow 0123401234 Green Blue Violet Gray White 5678956789 Band 1 (closest to the end) – first digit Band 2 – second digit Band 3 – power of ten multiplier (most cases simply the number of zeros) Band 4 – tolerance (Red = 2%, Gold = 5%, Silver = 10%, none = 20%) Resistor Color Band Code 4

5. What is “Tolerance” about? If a resistor has a nominal value of 1000 Ω and a tolerance of ± 10 % then individual resistors with the same nominal value are allowed to vary in their actual values from 900 Ω to 1100 Ω and still be considered acceptable. Any resistor fabricated with an actual value outside that range should be rejected as “not meeting specifications”. 5

6. Practice Problems Brown Green Red Silver Yellow Violet Orange Gold Red Red Red 6 Determine the nominal value of resistance and the tolerance for resistors having the following color codes. Determine the color code to specify each of the following resistors 1 kΩ 390 kΩ 56Ω