Resistive Circuits. Basics

1. EE188L EE I Laboratory
Lab #2
Resistive Circuits

2. Objectives of Lab #2
 Understand series and parallel
connections
 Understand the protoboard and Digital
Multimeter
 Measure and calculate equivalent
resistance
 Measure voltage difference between
nodes

3. Overview of Lab #2 Activities
 Connecting 4 identical resistors together
 Putting different resistors in series
 Putting different resistors in parallel

4. Protoboard
Good for making prototype
circuits
Note: POWER ON button
3 power supplies
+5, +15 and -15 volts
White grid
•Holding devices
•Making connections
Some underneath
Some with wires

5. Simple Circuit Wiring Example
+5 V 1 k
Red wire
Black wire
Useful hints to make connections to power supplies
 Unscrew plastic nut of power connections
 Insert wire in hole in post and tighten nut
 Don’t tighten only onto the wire’s insulation

6. Protoboard Power Supplies
+5 V +15 V -15 V
+5V at
1.0 AMP
+15V at
0.5 AMP
-15V at
0.5 AMP
3 power supplies with common ground
• Must connect between ground and one
red terminal
• Shows maximum current available
Do not short terminals together! Note fuse on side.

7. Protoboard Connections
Connections underneath:
•Long rows across the top is connected
•Each row of 5 is connected
•Each column is connected

8. Digital Multimeter = DMM
Can measure voltage, current, resistance, and diode turn-on voltage
Gives digital readout

9. Measuring Resistance with the DMM
1. Red probe is in correct position
2. Make sure the button with  is pressed
3. Place red and black probes on two terminals
when not connected to power
4. Read value of resistance on display and note the units

10. Measuring DC Voltage with the DMM
1. Red probe is in correct position
2. Make sure the button with V= is pressed to measure DC voltage
3. Place red and black probes on two nodes
4. Read value of voltage displayed and note the units
+ 5.06 V -
Red probe Black probe
Note 5.06 has 3 significant figures and 5.064 has 4 significant figures.

11. Measuring DC Current with the DMM 2
1. Connect DMM in series in the circuit
2. Red probe is in one of current ports (100ma max or 10A max)
3. Make sure the button with A= is pressed to measure DC current
4. Read value of current flowing into red probe on display and note the units
5 V
Resistor
Network
DMM
I
I

12. Measuring DC Current with the DMM 1
DMM connection is tricky
Open circuit and insert DMM
Reading is current flowing into red probe
5 V
Resistor
Network
DMM
I
I

13. Resistor Color Code
http://www.elexp.com/t_resist.htm
56 * 10 k = 560 k
237 * 1  = 237 