Lab 3: Audio Amplifier Part 2

Purpose

Lab 3 has many aims to familiar the students with several types of amplifiers. In the first part of Lab 3 we analyzed these two amplifiers:

• Common-collector(CC)amp

• CE-CC two stage amp

The summary of the data about these amplifiers can be found in the previous lab memo. This lab memo covers five different circuits. The objective was to become familiar with, analyze, and construct the following amplifiers:

• Class AB push-pull amp

• CE-class AB two stage amp

• LM386 audio amp

Summary

Because part 2 of Lab 3 contained so many circuits, the best way to quickly see the results of each amplifier is in the Table 1. Following the table there are schematics of the three circuits built.

When looking at the table, one can see that the LM386 is an optimal audio amplifier. This is the amplifier I will use in my radio design. There are several reasons this amplifier is the best choice. First, it has the highest gain. Second, it has the lowest power dissipation. Third, it takes up the least amount of space while being easy to wire.

Suggestion

It would be nice if we could verify our pre-lab values prior to lab to check our in-lab values. For example, I thought I had built my circuit incorrectly because it did not match my expected value from pre-lab. After spending majority of lab verifying and re-verifying my circuit, I decided to write my results though they disagreed with pre-lab. Outside of lab, I found my pre-lab value was wrong, and it cleared up misconceptions I had when that was checked.

Table 1: Lab 3b summary of all data found

Figure 1: AB push pull amplifier

Figure 2: LM386 audio amplifier