# 19.4: Procedure

## 19.4.1: Collector Feedback - DC Load Line

1. Consider the circuit of Figure 19.3.1 using Vcc = 12 volts, Rb = 220 k$$\Omega$$ and Rc = 1 k$$\Omega$$. Determine the ideal end points of the DC load line and the Q point, and record these in Table 19.5.1.

## 19.4.2: Circuit Voltages and Beta

2. Continuing with the component values indicated in step one, compute the theoretical base, emitter and collector voltages, and record them in Table 19.5.2 (Theory).

3. Build the circuit of Figure 19.3.1 using Vcc = 12 volts, Rb = 220 k$$\Omega$$ and Rc = 1 k$$\Omega$$. Measure the base, emitter and collector voltages and record them in the first row of Table 19.5.2 (Experimental).

4. Measure the base and collector currents and record these in the first row of Table 19.5.3. Based on these, compute and record the experimental beta as well.

5. Swap the transistor with the second transistor and repeat steps 3 and 4 using the second rows of the tables.

6. Swap the transistor with the third transistor and repeat steps 3 and 4 using the third rows of the tables.

## 19.4.3: Stability

7. Based on the measurements of Table 19.5.3, determine the maximum percent change of collector current and record in Table 19.5.4. Also determine the maximum percent change of beta and record in Table 19.5.4.

## 19.4.4: Emitter Feedback - DC Load Line

8. Consider the circuit of Figure 19.3.2 using Vcc = 12 volts, Rb = 220 k$$\Omega$$, Re = 470 $$\Omega$$ and Rc = 330 $$\Omega$$. Determine the ideal end points of the DC load line and the Q point, and record these in Table 19.5.5.

## 19.4.5: Circuit Voltages and Beta

9. Continuing with the component values indicated in step one, compute the theoretical base, emitter and collector voltages, and record them in Table 19.5.6 (Theory).

10. Build the circuit of Figure 19.3.2 using Vcc = 12 volts, Rb = 220 k$$\Omega$$, Re = 470 $$\Omega$$ and Rc = 330 $$\Omega$$. Measure the base, emitter and collector voltages and record them in the first row of Table 19.5.6 (Experimental).

11. Measure the base and collector currents and record these in the first row of Table 19.5.7. Based on these, compute and record the experimental beta as well.

12. Swap the transistor with the second transistor and repeat steps 3 and 4 using the second rows of the tables.

13. Swap the transistor with the third transistor and repeat steps 3 and 4 using the third rows of the tables.

## 19.4.6: Stability

14. Based on the measurements of Table 19.5.7, determine the maximum percent change of collector current and record in Table 19.5.8. Also determine the maximum percent change of beta and record in Table 19.5.8.

## 19.4.7: Troubleshooting

15. For the emitter feedback bias circuit, consider each of the individual faults listed in Table 19.5.9 and estimate the resulting base, emitter and collector voltages. Introduce each of the individual faults in turn and measure and record the transistor voltages in Table 19.5.9.