Lab 3: Voltage Dividers

Intro:

The purpose of this lab is to specify the characteristics of an unregulated power supply with three loads.

Experiment:

Data:

If R1= R2 = R3= 1K ohms

R_{EQ max} = 1000 ohms

R_{EQ min} = 333.3 ohms

V_BUS

V_BUS,max =  6.25V

V_{BUS, min} = 7.25V

Using V_BUS = Vs*R_EQ/(R_S+R_EQ)

            Vs= 6.53          Rs= 45.45

Using ohms law

 I_BUS= V_BUS/(RS+R_EQ)

            I_BUS,max=5.98 mA

            I_{BUS, min}= 15.18mA

Analysis:

Percent voltage variation

            5.81-5/5=16.2%                       5±16.2%

If added a fourth 1K resistor

            Resistance = 1000/4 = 250 ohms

            V_Bus = Vs*R/(R+R_L) = 6.53*250/(45.45+250)= 5.52V

If we wanted to reduce the load voltage variation to 1% we want V_Bus= 5.001.