1) Introduction: A resistor is a linear device because its voltage and current are proportional in either direction. A diode, on the other hand, in a nonlinear device because its

current and voltage are not proportional. Furthermore, a diode a unilateral device because it conducts well only in the forward direction. In this experiment you will measure diode currents and voltages for both forward and reversed bias. This will allow you to draw the diode curve. Also included are troubleshooting, design, and computer options. 2) Equipment: One power supply: adjustable from approximately 0 to 15V. One diode: 1N914 Three 2-watt resistors: 220ohm, 1Kohm, 100kohm. One VOM (analog or digital multimeter) - One milliammeter or another VOM if available graph paper, rectangular coordinates. - 3) Procedure: 1. Using the VOM as an ohmmeter, measure a 1N914's DC forward resistance and reverse resistance on one of the middle resistance ranges. If the diode is all right, you should have a reverse/ forward ratio greater than 1000:1. 2. Connect the circuit of Fig. 4-1 using a current-limiting resistor of 1kohm. For each voltage listed in table 4-1, measure and record the diode voltage V and the diode current /. 3. Calculate and record the DC forward resistance of the diode for each current of table 4- 1. 4. Reverse the voltage source in fig. 4-1. For each source voltage of table 4-2, measure and record the diode voltage V and the diode current /. 5. Calculate and record the dc reverse resistance of the diode for each source voltage of table 4-2. 6. Graph the data of tables 4-1 and 4-2 to get a diode curve (/ versus V). 7. The forgoing steps prove that the diode conducts easily in the forward direction and poorly in the reverse direction. Its like a one-way conductor. With this in mind, estimate the diode current in Fig. 4-2a and b. Record your ballpark estimates in Table 4-3. 8. Connect the circuit of fig. 4-2a (forward bias). Measure and record the diode current in Table 4-3. 9. Connect the circuit of fig. 4-2b (reversed bias). Measure and record the diode current. 10. Connect the circuit of fig. 4-3. Estimaate the laod voltage V, and record in table 4-4. Then measure and record V₁. 11. Short the diode with a jumper wire. Estimate V₁ for this condition and record in table 4- 4. Measure and record VL. 12. Reverse the jumper wire. Disconnect one end of the diode. Estimate V, and record. Next, measure and record V₁. 13. Select a voltage and a current-limiting resistance to produce 10 milliamps in fig. 4-1a. Connect your circuit and measure the current. Record your values of Vs and Rs, along with the measured / in table 4-5. HET Figure 4-1 R$ w 4) Data: Table 4-1. Forward Bias Vs V OV 0.5 V 1 V 2 V 4 V 6 V 8 V 10 V 15 V 10 V 1 1 k2 220 n 10 V 100 k R (No entry) 220 12 Table 4-2. Reverse Bias Vs -1 V -5 V -10 V -15 V Table 4-3. Diode Conduction Fig. 4-3a Fig. 4-3b V Normal diode Shorted diode Open diode Table 4-4. Trouble Shooting Estimate I 5) Conclusion: Estimate VL Plot V v.s. I in Table 4.1 1 Measured I Measured VL R