Tempo measurement, display, and control system for an electronic musical instrument

In an electronic musical instrument having means for automatically producing a preselected rhythm accompaniment having a desired tempo, tempo control apparatus having a tempo control for setting the desired tempo, said apparatus comprising:

• capacitor means;
• variable resistor means for determining a sampling pulse width corresponding to the desired tempo, said variable resistor means being connected between said capacitor means and a source of voltage, said variable resistor means also being adjustable by the tempo control;
• means for causing said capacitor means to begin charging at a rate determined by the setting of said variable resistor means;
• pulse width measuring means for measuring the period of time after said capacitor means begins charging at the rate determined by the setting of said variable resistor means until the voltage on said capacitor means reaches a predetermined value;
• means for causing said capacitor means to begin charging at a rate determined by the maximum setting of said variable resistor means;
• maximum pulse width measuring means for measuring the period of time after said capacitor means begins charging at the rate determined by the maximum setting of said variable resistor means until the voltage on said capacitor means reaches a predetermined value;
• and
• digital data processing means for processing the measurements made by said pulse width measuring means and said maximum pulse width measuring means and producing a count corresponding to the setting of said variable resistor means, wherein the count produced corresponds to a ratio including both measurements.