Analogue Electronics Project Report : Metronome and Pitch Generator Circuit

A simple metronome circuit based on a 555 timer was constructed in the electronic simulation program, PSPICE, demonstrating the feasibility of the design concept. A more complicated circuit capable of functioning as a metronome or pitch generator was then successfully implemented on a breadboard circuit. This circuit uses a crystal oscillator circuit for frequency generation and a phase-locked loop for synthesis of other frequencies which can be set with counter switches. A printed circuit board was designed for the final implementation. Introduction The metronome is defined as “a device used to mark time by means of regularly recurring ticks or flashes at adjustable intervals” (1). It is usually used to keep a standard tempo (steady beat) throughout a piece of music and may be used in practice or performance of a musical composition. An instrument of this type was first described in a paper by Etienne Louli in 1696, and Enbrayg (1732), Gabory (1771) and Harrison (1775) are also known to have made attempts at such devices. The first practical metronome was constructed in 1812 by Dutchman Dietrich Nikolaus Winkel. However, its invention is usually attributed to Johann Nepomuk Maelzel, of Ratisbon, who copied Winkel’s design received a patent for the metronome in 1816. The original metronome was a mechanical device consisted of a double pendulum with a sliding weight, the position of which is used to set the frequency of oscillation. It was modified in 1882 so that a click is produced on each swing of the pendulum rod, rather than being silent. Other approaches have included a clockwork metronome that produces a ticking sound on each beat until it runs down. Generally metronomes can be set to produce a certain number of beats per minute and it is important that the timing is reliable and regulated. Some metronomes may even produce two or more distinct sounds so that one sound indicates the beginning of each measure, and another indicates the beat within each measure. Today, many metronomes are electronic with a dial or buttons used to set the tempo. Advantages over the classical spring-powered mechanical metronome are that they do not need to be rewound, and that they are easily portable. Also, some may include an LED that flashes on the beat, an adjustable volume control, and/or the generation of a tuning note. A note is generated by selecting the corresponding frequency, for example, the note A is the frequency 440Hz, C = 523Hz, D = 587Hz, F = 698Hz, G = 784Hz, A = 880Hz.