It is used in teaching music in rhythmic gymnastics, in experiments in physics etc. a Metronome, a scheme which offers Bulgarian journal “Radio Television Electronics” (see Fig.), gives not only audio but also visual signals. With the help of variable resistors R1, R2 their frequency change in the range of 40 to 200 cycles / min. which corresponds to the musical pace from “grave” to “Prestissimo”.
A master oscillator is executed on a different structure of the two transistors V1, V2, V3 amplifier stage, operating in key mode at a dynamic head B1. Light signals generates the standby multivibrator V4, V5, which then increases the SIC transistors V6, V7.
All transistors, except for V7, silicon, low-power V7 should be of medium power, such as КТ603.