05-15-2023-2009 - Signal Generator, Tone Generator, Sound Module, Arbitrary Waveform Generators, Digital Pattern Generators, Function Generators, RF and microwave signal generators, pitch generators, measurement bridge, ESR, square-wave generator, square, square-wave, oscilloscope, sinewave generator, AC voltmeter, voltage divider, alternating voltage, reactance, capacitor, system, surroundings, etc. (draft)

"Tone generator" redirects here. For an electronic musical instrument, see Sound module.

A signal generator is one of a class of electronic devices that generates electrical signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typically used in designing, testing, troubleshooting, and repairing electronic or electroacoustic devices, though it often has artistic uses as well. ^[1]

There are many different types of signal generators with different purposes and applications and at varying levels of expense. These types include function generators, RF and microwave signal generators, pitch generators, arbitrary waveform generators, digital pattern generators, and frequency generators. In general, no device is suitable for all possible applications.

A signal generator may be as simple as an oscillator with calibrated frequency and amplitude. More general-purpose signal generators allow control of all the characteristics of a signal. Modern general-purpose signal generators will have a microprocessor control and may also permit control from a personal computer. Signal generators may be free-standing self-contained instruments, or may be incorporated into more complex automatic test systems. 

https://en.wikipedia.org/wiki/Signal_generator

Methods of ESR measurement

Measuring ESR can be done by applying an alternating voltage at a frequency at which the capacitor's reactance is negligible, in a voltage divider configuration. It is easy to check ESR well enough for troubleshooting by using an improvised ESR meter comprising a simple square-wave generator and oscilloscope, or a sinewave generator of a few tens of kilohertz and an AC voltmeter, using a known good capacitor for comparison, or by using a little mathematics.^[2]

A professional ESR meter is more convenient for checking multiple capacitors rapidly. A standard measurement bridge, and many LCR and Q meters, can also measure ESR accurately, in addition to many other circuit parameters. The dedicated ESR meter is a relatively inexpensive special-purpose instrument of modest accuracy, used mainly to identify capacitors with unacceptably large ESR and sometimes to measure other low resistances; measurements of other parameters cannot be made. 

https://en.wikipedia.org/wiki/ESR_meter