Musical & effects

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.....

Fuzz box 1

The input signal is amplified by the transistors. The distorted output is then clipped by the two diodes and the high frequency noise is filtered from the circuit via the 500 pF capacitor..

Tremolo

This simple circuit can color the sound coming from your audio system. Clocking for the circuit is provided by an oscillator built from one quarter of a 4093 quad NAND Schmitt trigger. With the component values shown, it will run at about 5 Hz. The clock frequency is fed to the gain control, pin 8, of an LM386 amplifier. Tremolo is produced by varying the amplifier gain. A trimmer potentiometer can be put in series with R1, to easily experiment with different.....

Multi-Instrument Melody Generator UM34811A

This circuit is based on a preprogrammed multi-instrument melody generator IC, containing a 512-note memory capable of generating 16 tunes. The comprehensive control facilities enable playing - all tunes repeatedly or stopping at the end, - or one tune repeatedly or stopping at the end. ..

Guitar fuzz

The 741 has a maximum gain of 20,000, but the circuit is so designed that the IC"s gain is 2,700,000 which then distorts the output. This distortion gives the fuzz effect. The two diodes clip the output to drop the level, also lowered by the potential divider..

Race-car-motor-crash

For two simultaneous race-car sounds. ..

Stereo reverb system

The LM378 dual power amplifier is used as the spring driver. The recovery amplifier is a low noise dual preamplifier..

Audio noise generator

This simple circuit generates both white and pin noise. Transistor Q1 is used as a zener diode. The normal base-emitter junction is reverse-biased and goes into zener breakdown at about 7 to 8 volts. The zener noise current from Q G flows into the base of Q2 such that an output of about 150 millivolts of white noise is available. To convert the white noise to pink, a filter is required which provides a 3 dB cut per octave as the frequency increases..

Fuzz box 4

None of the components are particularly critical in value or quality, as distortion is the sole object..

Micrometronome

This compact metronome will run for years on a single nine-volt transistor battery. Has both tone and pulse rate controls, and uses touch plates to start and stop, can be built in a case no larger than a pack of cigarettes. The touch plates consist of two strips of metal about 1/16-inch apart mounted on, but insulated from, the case..

Voltage-controlled amplifier or tremolo circuit

The transistors form a differential pair with an active current-source tail. This configuration, known technically as a variable-transconductance multiplier, has an output proportional to the product of the two input signals. Multiplication occurs due to the dependence of the transistor transconductance on the emitter current bias..

Electronic Bagpipe

The electronic bagpipe mimics the sound of real instruments. This circuit uses two UJT oscillators and an amplifier (Q3,..

Music synthesizer

Three modes of operation are available in the music synthesizer mode..

Low-voltage-compander

The NE575 is a dual-gain control circuit designed for low voltage applications. The NE575"s channell is an expander, while channel2 can be configured either for expander, compressor, ..

Stylus organ

IC2 is an audio frequency oscillator. Its frequency is primarily controlled by the resistance between pins 2 and 7. RV4-11 eontrol the oscillator frequency and by touching a stylus (connected via limiting resistor R5 to pin 2) to each preset, different notes can be played. ICl is a low frequency oscillator (approximately 3-10Hz), the frequency of which is variable by RVl..

Linear optocoupler for instrumentation

A dual optocoupler is used in a configuration which has the same current throughout as the LEDs. Assuming similar optocoupler features the output voltage must be equal to the non-inverting input voltage. Since the op amp is within a closed loop the output voltage becomes equal to the input voltage. ..

Whooper

Integrated circuit Ul is connected as a low-frequency asymmetrical oscillator. Its output is inverted by Ql and fed to the reset te..

Tone burst generator

The tone burst generator supplies a tone for one-half second after the power supply is activated; its intended use is a communications network alert signal. Cessation of the tone is accomplished at the SCR, which shunts the timing capacitor CI charge current when activated. The SCR is gated on when C2 charges up to the gate voltage which occurs in 0.5 seconds. Since only 70 ?? are available for triggering, the SCR must be sensitive enough to trigger at this level...

Steam locomotive whistle

The waveform of a steam whistle is a complex combination of white noise and an audio frequency oscillation. The noise generator is a transistor (Ql) biased into zener mode. The audio frequency oscillation is a straightforward mixture of two similar (but not identical) sine waves, which after their addition produce a more complex waveshape. The sine wave generators are twin-t oscillators...