Sight and Sound Metronome Circuit Diagram. Precise, adjustable control of beats per minute from a largo of 18 to a frenzied, high presto of 500, These beats are produced acoustically through a speaker. A light flashes at the same rate. When SW1 is closed, CI begins to charge through Rl and R2. Cl will eventually reach a voltage at which the emitter of unijunction transistor is switched on, `dumping` the energy stored in Cl into an 8 ohm speaker.
To produce a distinct `plop`, brief pulses across T2 secondary drive Q2 into conduction. The extra gain of Q3 and Q4 are sufficient to briefly switch LI on,
then o£f; as the pulse wave pas-ses. Capacitor C2 `stretches` the
puise slightly to overcome the thermal inertia of the lamp, so that a
bright flash occurs,.
Sight and Sound Metronome Circuit Diagram
