Fun with function generators.

Couple a function generator to an oscilloscope to form a versatile instrumentation set for testing systems and components.

THE FUNCTION GENERATOR IS A versatile test instrument that usually functions as a signal substitution source. This article explains how the function generator, when coupled to an oscilloscope, becomes an even more versatile instrumentation set for testing and evaluating systems and components.

The function generator is an instrument that permits the introduction of its signals at specific points in a circuit. This characteristic makes it useful as an audio generator for testing, troubleshooting, and evaluating audio products as well as conventional electronic circuit components.

The oscilloscope paints the "signatures" of electronic components on its screen and a digital multimeter (DMM) makes the routine electrical measurements necessary to perform the tests discussed in this article. In addition to its role in testing, this instrument suit is very effective teaching tool for explaining the behavior of both active and passive components to students.

What do you need?

To perform the tests and demonstrations described in this article, the function generator, oscilloscope and DMM should have the following minimum specifications:

* Function generator--2-MHz internal sweep

* Oscilloscope--two-channel, 20-MHz with X-Y operation

* Digital multimeter--capable of making the basic electrical measurements with a basic DC accuracy of at least 1.0%

Manufacturers of function generators position the controls and connecting plugs in different ways on the instruments that are designed to fill various market segments. Therefore, there really are no standard signal generators. If your function generator differs from the one shown in Fig. 1, you might want to consult your manual to review the functions of all of its controls.

Fortunately, most signal generators have the same basic controls and input terminals that can be interconnected in the same way. The leading signal generator specifications are: frequency range, sinewave distortion, types of waveforms generated, sweep range, and signal output level.

Selecting a function generator

If you do not own or have access to a signal generator, there are some points to consider when selecting one. …