Introduction to Biasing

Objective:
The purpose of this lab was to find appropriate biasing resistors so that two LEDs would light up within their power ratings. Applying KCL and KVL to the circuit and adjusting the calculated resistances to practical resistor values will make the circuit operate correctly.

Procedure:

First we modeled the circuit to be used and calculated what the maximum resistances across the LEDs should be.
R_led1= 5V/0.02275A = 219.78 ohms
R_led2= 2V/0.02A = 100 ohms









Then we could find the minimum resistances R1 and R2 from the maximum current and LED voltages from the circuit.

As a practical matter we chose to use:

R1=150 ohms + 40 ohms =190 ohms
R2=360 ohms

Here was the circuit incarnate:









The data revealed some interesting behaviors. Removing one LED would raise the voltage and current of the other resistor.

Conclusion:
We were able to bias the circuit successfully to light both LEDs with a 9V source. According to my efficiency equation the minimum voltage to power the LEDs  in the Figure 2 configuration would be 3.6V. The answers to the final questions are below.