GB1280117A - Electronic metronomes - Google Patents

Abstract

1280117 Electronic metronomes A PAQUET 20 July 1970 [21 July 1969 18 June 1970] 35078/70 Heading G3T An electronic metronome emits, in synchronizm and at a selectable frequency, sound and visual signals the visual signals being from two lamps which are lighted alternately. The metronome circuit, Fig. 1, comprises a bi-stable multi-vibrator including transistors Q 3 , Q 4 and Q 5 , Q 6 which is switched from one state to another by a time constant circuit including R 1 , R 2 , C 1 . The capacitor C 1 is charged via R 1 , R 2 to a voltage V at which transistors Q 1 , Q 2 conduct, so that C 1 discharges therethrough. A negative pulse is consequently passed via C 2 to switch the multi-vibrator. The multi-vibrator energizes coil 10 lamp L 1 and coil 10' lamp L 2 , alternately. As shown in Fig. 2a, cores 12, 12' are alternately drawn into respective coils 10, 10' striking a plate 13 thereby producing the sound output of the metronome. Alternatively, as illustrated in Fig. 4 (not shown), the sound output is from a loudspeaker connected in series with a thyristor which is controlled by the R.C. circuit. The multivibrator is switched by pulses produced when the thyristor conducts and controls the lamp signals only, in synchronizm with the sound signals. In both circuits the output frequency of the metronome is selectively adjustable by adjusting resistor R 2 in the R.C. circuit.