Musical & Effects Circuits
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The expander to complement the compressor is shown. An external op amp is used for high slew rate. Both the compressor and expander have unity gain levels of 0 dB. Trim networks are shown for distortion (THD) and de shift. The distortion trim should be....
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ICla and IClb form an astable multivibrator. The astable"s signal is fed to IC1c, also to the clock input of IC2, a 4017B decade counter. That IC"s QO through Q9 outputs become high one at a time for each successive clock pulse received at1Jin 14. Switch....
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ICl, a 555 timer, is set up as an astable multivibrator to produce the signal that triggers IC2, a 7490 decade counter. That IC, in turn, produces a BCD output that is fed to IC3, a 7445 BCD-to-decimal decoder/driver. IC3"s output is inverted by two hex....
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A variable dock-pulse generator is made up of two sections of IC1 (a 4069 CMOS hex inverter). Rl, Sl, and capacitors Cl through C6. By adjusting Rl and switching one of the capacitors into the circuit, the clock"s pulse rate can be varied over a wide....
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A CA3240 dual MOSFET-input device is used as a white-noise source. Op amp IC2 is used as a driver stage for the push-pull output stage formed by Q5 and Q6. Transistors Q2, Q3, and Q4 form a variablefrequency multivibrator. Rll, the speed control, is used....
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Transistors Ql and Q2 form the two halves of a free-running multivibrator whose frequency is determined by the voltage across C8. That capacitor is charged and discharged by closing and openingBwitch Sl. Transistors Q3 and Q4 make up a VFO. The output of....
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The VCO of Ul, a phased-locked loop. produces a low-frequency square-wave signal from 5 Hz to 2500Hz, which is controlled by varying the voltage to pin 9 via R2. The frequency threshold is set by Rl and Cl. Increasing the value of Rl increases the....
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A phase shift oscillator using the LM324 operates at an adjustable rate, 5-10 Hz, set by the speed pot. A portion of the oscillator output is taken from the depth pot and used to modulate the on resistance of two 1N914 diodes operating as voltage....
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The tremolo effect is generated by a repeating volume change at a rate usually between 1 and 15Hz. The timer produces a low frequency square wave that is smoothed by a simple rc integrator. This varying signal modulates the signal input from the....
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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....
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Often the frequency of a signal must be doubled: modulator/demodulator chip LM1496 is an ideal basis for this. From..
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In this circuit, Ql is a simple amplifier that has its gain controlled by a variable emitter resistance supplied by FET Q2. In ..
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This circuit uses an SAD 512D (Reticon) chip, which is a 512-stage analog shift register. By varying th..
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A gate voltage is applied to initiate the proceedings. When the gate voltage is in the ON state, Q..
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This bull horn uses U1 as a driver stage and U2 as an output driver. U1 is set up for a gain of 200. The microphone should have a..
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The receiver is an audio amplifier fed by SPKR1, a piezo speaker that is used as a microphone. A scope or headphone..
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Integrated circuit Ul is connected as a low-frequency asymmetrical oscillator. Its output is inverted by Ql and fed to the reset te..
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The electronic bagpipe mimics the sound of real instruments. This circuit uses two UJT oscillators and an amplifier (Q3,..
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As shown, three ICs are used to produce the sounds. ICl is a 555 timer that generates clock pulses. It is configured as an astable multivibrator. The frequency of the clock pulses is set by trim: mer potentiometer PI. These clock pulses are coupled to the....
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The space-age sound device uses a 556 dual-times IC to produce a phasor sound. That IC is actually two 555 timer ICs in one 14-pin package, as shown in the schematic. Each timer inside the 556 is connected iri an astable multivibrator mode. The first timer....
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The electronic gong is comprised of an oscillator (built around half of a 74COON quad 2-input NAND gate), an active twin-T filter (built around a TL081), and will drive an audio amplifier IC such as aii LM386N. Pulses from astable multivibrator ICl cause....
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An outside horn-type speaker works best with the circuit. However, such devices require a great deal of power, so this sounder should only be used in alarm circuits where at least a 6-A SCR is used as the sounder driver. A single CMOS 4001 quad 2-input NOR....
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This is a simple low-level noise maker that`s ideally suited to certain alarm applications. When the sounder is located in another part of the building, the sound level is loud enough to be heard, but is not loud enough to warn off an intruder. A single....
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The circuit consists of four parts: a binary counter, a D/A converter, a VCO, and an audio output amplifier. The speed at which the counter counts depends on the frequency of the output of the VCO, which in turn is determined by the output of the counter.....
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Half of a Motorola MG14538B dual, precision, retriggerable mono stable multivibrator is used to form an extended on-time timer circuit. That type of circuit can be used as a switch debouncer. Such circuits are often used in digital circuitry, where each and....
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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....
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By adding a small amount of noise to a signal to be digitized (about 0.7 bit): where: n = #..
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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....
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The UJT-oscillator frequency is determined by the 100 µ¥ capacitor and the effective resistance of the 22 and 470 resistors and the potentiometer. Rate can be varied from 42 to 208 beats/minute.
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Twang is a guitar sound that more or less approximates a banjo or mandolin. The circuit produces unusual sounds from an ordinary electric guitar by cutting the bass, severely distorting the midband and highs, and then amplifying the distortion...
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The heart of the circuit is IC2, a 50240 top-octave generator. That device uses a single input-frequency to generate all twelve notes of the musical scale. The input signal is provided by IC1, a 4001 quad 2-input NOR gate. Two sections of that IC are used to....
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The electronic circuit in the VOX Box consists of three parts: a microphone preamplifier, a Schmitt trigger, and a relay driver. Input signals (MIC INPUT terminals) to the microphone preamplifier (Ul) are amplified and fed to a THRESHOLD control (R8). When....