1Z0-931 Autonomous Database

Lab #24

Approximating Ideal Voltage

and Current Sources

Introduction:

To construct approximate constant voltage and constant current sources.

Theories:

V_L = (R_L/(R_L + R_S))(V_S)
I_L = (R_S/(R_s + R_L))(I_S)

Results:

R_S = 1 kΩ
V_S = 10 V
I_S = 10 mA

Table 24-1 Calculated Data

Approximate Constant Voltage Source
RL (kΩ)	10	17	22	33	46
VL (V)	9.09	9.44	9.57	9.71	9.79
IL (mA)	0.91	0.56	0.43	0.29	0.21

Table 24-2 Calculated Data

Approximate Constant Current Source
RL (Ω)	18	33	47	68	100
VL (V)	0.18	0.32	0.45	0.64	0.91
IL (mA)	9.82	9.68	9.55	9.42	9.1

Table 24-3 Measured Data

Approximate Constant Voltage Source
RL (kΩ)	10	17	22	33	46
VL (V)	9.07	9.47	9.54	9.69	9.8
IL (mA)	0.91	0.56	0.43	0.29	0.21

Table 24-4 Measured Data

Approximate Constant Current Source
RL (Ω)	18	33	47	68	100
VL (V)	0.174	0.31	0.45	0.611	0.899
IL (mA)	9.67	9.89	9.57	8.98	8.99

Laboratory Questions:

1. (a) R_L >> R_S
2. (a) R_L << R_S
3. (a) true
4. (a) true
5. For an approximate constant voltage source behavior, as R_L increases, the load voltage remains relatively constant to the V_S while the current drops. For an approximate constant current sources behavior, as R_L increases, the load current remains relatively the constant to the I_S while the voltage drops.

Conclusion:

Concluded from this lab was that for a constant voltage source, the load resistance must be greater than the source resistance in order for the load voltage to remain close towards the voltage source and the current to drop.  In a constant current source, the load resistance must be less than the source resistance in order for the load current to remain close towards the current source and the voltage to drop.