EE222 Lab 5 Instructions

### EE 222 Electronics I Fall 1995 LAB 5

NOTE: This file is available on the World Wide Web (WWW) on coral at the file location

Lab dates: 10/23/95 and 10/25/95

Lab report due: Monday, November 6, 1995 by 2 pm.

Related Reading: S &S, Sec 3.7.

## NIFTY DIODE CIRCUITS

In this lab, you will use diodes in several interesting circuits and explore the function of these circuits.

WRITE-UP: Your report for this lab will be different than our usual EE222 write-up. Please write a 1 page memo (exclusive of figures) to your classmates describing the basic function of your circuit. You may write one memo per group for this assi gnment and you must write it in HTML format so that it can be placed onto the World Wide Web. Your memo will be your classmates' resource for learning about your circuit. Since we have not discussed these circuits in lecture yet, I do not expect detaile d theoretical explanations for their function. You may sketch the requested plots including appropriate scale information or submit oscilloscope plots.

### PROCEDURE

• For the diodes in this lab, use standard Si diodes (either the 4007 or 1N4148/914) unless the diode is marked with a "Z" which refers to a Zener diode.

• Voltages marked as VBIAS are DC voltages.

• Use a 4V (peak) sinusoidal voltage as the input voltage, Vin, for your initial analysis.

1. What does the circuit do? Can you suggest a more descriptive name for the circuit?
2. What does the output voltage (Vout) look like as a function of time?
3. What does the transfer characteristic (Vout vs. Vin) look like?

• Additional items that should be considered for particular circuits are included with circuit diagrams.

### OPTIONAL

Feel free to experiment with other features of your circuit if you have time. These might include

• frequency dependence

• PSpice simulation

• switching the polarity of your diode(s)

• various AC input signals (sine wave of different magnitude, triangle wave, square wave)

• varying component values (e.g. Vbias, load resistors, capacitors)

### CIRCUIT 1

FIGURE 1: Circuit 1 Schematic

### CIRCUIT 2

FIGURE 2: Circuit 2 Schematic

Start with a fairly small value for C1 (on the order of nF). Try a 1 kHz input signal.

Experiment with values for R2 including infinity (open circuit, no load) and 10 kohm. What effect does a finite load (resistor R2) have on the output? (Hint: Think about what determines the response of the circuit as a function of time. Remember EE 20 9!)

### CIRCUIT 3

FIGURE 3: Circuit 3 Schematic

In your investigation of what this circuit does, consider looking at the DC voltage at the output. You might also want to look at the AC voltage across D1.

### CIRCUIT 4

FIGURE 4: Circuit 4 Schematic

### CIRCUIT 5

FIGURE 5: Circuit 5 Schematic

How will you choose which Zener diodes to use? What are your considerations?