Wiring Material

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 uni junction 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,.