Top Circuits Page 17
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Converter consists of four quad bistable latches activated in the proper sequence by the digit strobe output of the LD110. The complemented outputs (Q) of the quad latch set reflects the state of the bit outputs when the digit strobe goes high...
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Single programming resistor Rp provides an output-current range of about six decades.-Note that this resistor"s TC is also a potential source of error; it dissipates 125 mW when JliN ~ 5 V. The maximum deviation is typically 50 nA or 0.0002% of full scale. ..
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The circuit letsyou convert a serial pulse stream or sinusoidal input to a sinusoidal output at 1/32 the frequency. By varying the frequency of Vrn, you can achieve an output range ofl07:1-from about 100 kH2 to less than 0.01 H2. The output resembles that....
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This transmitter can be tuned to the FM broadcast band, 2 meters,-or other VHF bands by changing C5 and Ll. The values given for C5 and Ll will place the frequency somewhere in the FM broadcast band. Ll is 4 turns of #20 enameled wire airwound, % inch in....
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This is a sensitive, mini-powered FM transmitter consisting of an rf oscillator section interfaced with a high-sensitivity wide passband audio amplifier and capacitance microphone with built-in FET that modulates the base of the rf oscillator transistor.....
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The FM Snooper is an FM transmitter that radiates a continuous wave whose frequency is altered according to the sound waves striking the microphone. An ordinary FM broadcast receiver detects the transmitter"s output carrier. When 9-V battery, B1, is....
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Transistor Q1 acts as an amplifier for condenser microphone MIC1. The output of Q1 is applied to the base of transistor Q2 through a 4. 7 -I"F capacitor. C2 and 11 form an LC tank circuit. which is used to set the frequency at which the transmitter....
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Adjustable capacitor C10, and coil L1 form a tank circuit that, in combination with Q1, C2, and R1, oscillates at a frequency on the FM band. The center frequency is set by adjusting C10. An electret microphone, M1, picks up an audio signal that is....
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The 2N2222 circuitry is a three-element, phase-shift oscillator circuit, designed to yield a 1,000-Hz sine wave. The 1,000-Hz sine wave is then applied to the TCG-610 varactor diode, 6 pF at 4 V, which changes the tank capacitance, thus varying the rf....
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This transmitter has a range of up to 100 feet. It generates a complete multiplex stereo signal and is useful for cordless headphone applications in which an inexpensive socket stereo receiver can be used. ..
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The transmitter was designed specifically for use by radio amateurs as a radio beacon. As such, it provides a good-quality ..
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A simple FM wireless microphone uses a single BC183C transistor as an audio amplifier. A 2N3565 can be substituted. ..
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A BA1404 IC is used to generate a complete FM MPX signal. The chip contains all of the necessary circuitry. CI and R3, and R4 and C4 provide pre-emphasis. The transmitter runs on a single AA cell. L3 is 3 turns of #20 wire on a Ke drill (for a form). L3 is....
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The vacuum tube is still alive and useful in some applications, as in this CW transmitter, The circuit was built in old-fashioned breadboard style on a wooden base. Old table radios are a good source of parts for this circuit. V3 is used as a ballast....
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This tracking transmitter consists of four distinct subassemblies; a free-running multivibrator, a transmit switch, an audio-tone generator, and an FM transmitter. The multivibrator (which produces a pulse width with a pulse separation of 1500 ms) is built....
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This CW transmitter has an output of up to 3 W. By using 24 V on Q2, up to 10 W output can be obtained. If a 24-V supply is used, Ql must not see more than 12 V. Connect 12 V between junctions C3, R2 and L2, and remove L5. LI should be a low-Q 18- to 20-....
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An FM radio generates an interference signal that can be picked up on another FM radio tuned 10.7 MHz above the first one. The 50-k0 potentiometer adjusts the modulation level to maximum without distortion. The RC network improves the fidelity of the....
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The vu-meter is distinguished in two categories, those with the needle instruments and those with the led column. Whether it is a tube amplifier or integrated amplifier, a vu-meter sound level meter is required. Today there are enough chips that do this work....
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Sounds are picked up by MIC1 and fed to the input of the first op amp. The signal is then fed to the input of second op amp Ulb, where it is boosted again by a factor of between 1 and 33, depending upon the setting of range switch Sl. With the range....
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This circuit compares a rectified input, f."!N, with a voltage that decays exponentially across a 4. 7-KO resistor and a ·o.Ol-I"F capacitor. Comparing the exponentially decaying voltage with the rectified input provides a peak-level indication that....
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The indicator is intended for use with an audio amplifier or preamplifier, but it can also be used in othe..
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This single-stage amplifier (using a 2N2222 or 2N3904 general-purpose transistor) is useful for interfacing test in..
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This circuit is used to meter the audio power output of an amplifier feeding a speaker. RY1 is actuated if excess ..
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The input signal drives ICD. Because ICD"s positive input (V+) is slightly offset to + 0.1 V, its steady state ..
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The D169 serves as a level detector and provides complementary outputs. The op amp is used to integrate the input signal Vin with a time constant of R1C1. The input (must be negative) causes a positive ramp at the output of the integrator which is summed....
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The circuit accepts two positive-voltage inputs VN and Vv and provides a TTL-compatible output pulse train whose repetition mte is proportional to the ratio VN/ V0. Full-scale output frequency is about 100 Hz, and linearity error is below 0.5 percent. The....
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Circuit has a 1 Hz-to-30 MHz output, 150-dB dynamic range, for a 0 to 5 V input. It maintains 0.08% linearity over its entire 71/3 decade range with a full-scale drift of about 20 ppm/°C. To get the additional bandwidth, the fast )FET buffer drives the....
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The input voltage, V1, causes C1 to charge and produce a ramp voltage at the output of the 741 op amp. Diodes D1 and D2 are four-layer devices. When the voltage across C1 reaches the breakover voltage of either diode, the diode conducts to discharge C1....
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This circuit can accept positive or negative or differential control voltages. The output frequency is zero when the control voltage is zero. The 741 op amp forms a current source controlled by the voltage Ec to charge the timing capacitor C1linearly.....
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This stabilized voltage-to-frequency converter features 1 Hz -1.25 MHz operation, 0.05% linearity, and a temperature coefficient of typically 20 ppm/°C. This circuit runs from a single 5-V supply. The converter uses a charge feedback scheme to allow the....
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In this application, an AD652IC is used in a synchronized V/F converter that derives its input from th..
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Using a Burr-Brown VFC 32 IC, this voltage-to-frequency converter uses few components. The circuit values ..
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This voltage-to-frequency converter (VFC) accepts the bipolar-ac inputs. For -10- to + 10-V inputs, the c..
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In this circuit, CI is charged to a fixed reference level, then discharged. Integrator ICl circuit charg..
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In this circuit, integration is performed by using a conventional operational amplifier and feedback capacitor, CF. When the integrator's output crosses the nominal threshold level at pin 6 of the LM131, the timing cycle is initiated. The average current fed....
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The 741 op amp integrator signal is fed into the Schmitt trigger input of an inverter. When the signal reaches the magnitude of the positive-going threshold voltage, the output of the inverter is switched to zero. The inverter output controls the FET....
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This circuit is based upon the change of frequency of the function generator with the input voltage ViN· Generally, the frequency depends upon the capacitance and resistor connected to pin 6. This resistor is replaced by the FET. ..
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This circuit uses a programmable op amp such as the -HA2730-a two-amplifier monolithic chip with independent programming ports for each amplifier-whose slew rate and other parameters vary linearly with a so-called set current. The converter circuit uses....
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The current out is Iqut—Vin/R. For negative currents, a PNP can be used and, for better accuracy,-a Darlington pair can be substituted for the transistor. With careful design, this circuit can be used to control currents of many amps..
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This 5-V circuit utilizes a servo-controlled dc/dc converter to generate the compliance voltage necessary for loop-..
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This circuit switches its dc/dc converter, IC1, off whenever the large filter capacitor, C6, has suffic..
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This fixed frequency triangular waveform generator driven by a TTL square wave generates typically 16-V p-p triangles at frequencies up to several MHz. It uses only one AND open collector gate, or one open collector inverter as a fast integrator with gain.....
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Two pairs of MOSFETs form a bridge that alternately switches current in opposite directions. Two parallel-resonant LC circuits complete the converter. The Ll/C1 combination is resonant at the fundamental frequency; the L2/C2 combination is resonant at the....
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This circuit turns a sine wave into a square wave. It is comprised of a single 2-input NAND Schmitt trigger that`s configured as an inverter with a trigger level adjustment at its input. As the input voltage rises above the gate`s trigger point,..
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This divider uses a variable-length shift register, a type-D flip-flop, and an inverter. The clock feeds the..
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Counter speeds for CMOS- and TTL-programmable counters are limited to under 100 MHz. ECL-type devices can approach..
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The radio beacon band extends from 280 to 516 kHz. Each beacon has its own characteristic AM"-modulated morse-coded ..
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Ll, Ql, L2, and L3 compose an RF amplifier stage that feeds Ml, a doubly balanced mixer. Q4 is a l..
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The VLF Converter can be used to pick up signals for the general coverage of shortwave receivers. A number of unusual signals..
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This converter enables a receiver that tunes 28 to 32 MHz to receive the 144- to 148-MHz amateur band. A BF981 dual-gate ..
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In this case, the NE602 is used in this superhet front-end configuration. Ul serves as a frequency conve..
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Using a Signetics NE602, this converter tunes the 9.5- to 9.8-MHz range. An AM car radio is used as a..
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The NE602 chip, Ul, contains oscillator and mixer stages. The mixer combines the oscillator signal with the input RF signal to produce signals whose frequencies are the sum and difference of the input frequencies. For example, an 8.5-MHz oscillator and a....
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This converter enables reception of 800 to 1000 MHz on any scanner covering the 400 to 500-MHz range. The converter can be set up to cover either 800 to 900 MHz or by readjustment 900 to 1000 MHz. Sensitivity is very high because of the GASFET front end. ..
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The second gate (G2) of a MOSFET can be used to incorporate a crystal oscillator into the same stage as a frequency mixer. Although old hat with tubes, this scheme is seldom seen in dual-gate MOSFET circuitry. L3, 03, and XI form the crystal oscillator, and....
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Using the bilateral properties of a balanced mixer this transvertcr will produce 6-m output with 2-m inputs. Y1 is a 90-MHz crystal. Note that the input on 2 m is 143 to 144 MHz for 53 to 54-MHz output. This avoids possibility of extraneous 2-m reception....
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Most ATV (Amateur Television) transmitters transmit a DSB signal and commercial television stations use a VSB (Vestigial Sideband) signal. This fact is made use of in this converter to use the lower sideband. This results in less interference from repeaters....
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The circuit is an inverter set up as a linear amplifier. Adding the· crystal and capacitors to the feedback path, we turn the amplifier into an oscillator and force it to oscillate at, or least very near, the crystal"s resonant frequency. Trimmer capacitor....
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The converter generates an output voltage which is linearly proportional to the input frequency waveform. Each zero crossing at the comparator"s input causes a precise amount of change to be dispensed into the op amp"s summing junction. This charge in turn....
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This circuit converts frequency to voltage by taking the average dc value of the pulses from the 74121 monostable multivibrator. The one shot is triggered by the positive-going ac signal at the input of the 529 comparator. The amplifier acts as a dc filter,....
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Six components can configure a circuit whose output voltage is proportional to its input frequency. The average current (hvc from the 40106 Schmitt trigger inverter"s ground pin 8 is linearly dependent on the frequency at which CO is discharged into the....
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Teledyne Semiconductor"s Type TSC9402 is a versatile IC. Not only can it convert voltage into frequency, but al..
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In this circuit, the input from IC2 optocoupler is fed to the comparator input of the AD..
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The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
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This fast circuit is compatible with any amplifier that has a line or high-level input (radio, CD) that allows you to mix the
signals from a microphone with the music source of your choice also add sound effects to your voice,
which are adjustable in....
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The sound is taken from a musical instrument in two different ways. Through a microphone that is placed in place by the instrument amplifier or via a direct connection between the instrument and the mixing console via a direct-box device. The benefits of....
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It is a simple and reliable system for processing human speech. It has the task of altering the tone of the human voice and making it heard as artificial, such as the voice of a robot that, as it is known, is produced by artificial means. This is an easy but....
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The circuit consists of a white noise generator which only switches on with the high part of the square wave output from the clock circuit. The frequency of the clock is adjusted with the 10 pot and the output voltage of the clock is adjusted by the 100 k....
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The beat rate may be determined by operating a foot pedal in much the same manner as for a real drum, or by means of an internal oscillator, the speed of which may be preset.
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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..
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Q1 and Q2 form a voltage amplifier which has sufficient gain to be overdriven by a rela-tively low input, such as an electric guitar. The result is that the output from Q2 is a Squared-Off verson of the input, giving the required fuzz sound. RV1 adjusts the....
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Transistors Q1 and Q2 amplify the incoming signal, and the gain is such that the input will overload when used with an electric guitar. RVl adjusts the amount of feedback present, and hence voltage gain. The output is, therefore, a squared version of the....
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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..
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IC3 acts as an oscillator which operates if the output of ICl is high. With the values used the two frequencies produced are about 800 Hz and 2500 Hz. The output is buffered by Ql which drives the speaker. The first IC is used to generate the tone duration....
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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....
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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....
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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....
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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....
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A reverse-biased pn junction of a 2N2712 transistor is used as a noise generator. The second 2N2712 is an audio amplifier. The 005 µf capacitor across the amplifier output removes some high-frequency components to simulate pink noise more closely..
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The zener breakdown of a transistor junction is used as a noise generator. The breakdown mechanism is random and this voltage has a high source impedance. By using the op amp as a high input impedance, high ac gain amplifier, a low impedance, large signal....
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Twenty-five musical keys and 25 LEDs are provided to denote F to F" with half notes in between. Memory can store a played tune. There are ten preprogrammed tunes (each has an average of 55 note s) masked in the chip. Any tune can be recalled by depressing....
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When a gate voltage is applied, Ql is turned on and capacitor C is charged via the attack pot in series with the 1 K resistor varying this pot, attact time constant. A fast attack gives a percussive sound, a slow attack the affect of "backward" sounds. When....
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This circuit will synthesize two rear channels for quadraphonic sound when fed with a stereo signal. The rear output for the left channel, is a combination of the left channel input 180 out of phase, added to a proportion of the right hand channel (also out....
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The first timer is used as amonostable and determines the tone duration when triggered by a positive pulse at pin 6. The second timer is enabled by the high output of the monostable..
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The circuit is that of a multiple feedback bandpass filter. A short click (pulse), makes it ring with a frequency which is its natural resonance frequency. Oscillations die away exponentially and closely resemble many naturally occuring percussive or plucked....
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This waveshape generator is basically a slow running oscillator with variable attack and decay. A variable amplitude (high impedance) output is available via the 2M potentiometer. B shows an add-on circuit which should be used if a low impedance output is....
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The circuit generates low-level rf bursts having frequencies as high as 10 MHz, thus permitting field testing of high frequency receivers. A jumper-selectable binary fraction (liz to "1256 of the Y1 crystal frequency gates the output rf signal. Output....
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Compression and expansion ratios other than 2: 1 can be achieved by the circuit shown. Rotation of the dual potentiometer causes the circuit hook-up to change from a basic compressor to a basic expander. In the center of rotation, the circuit is 1:1, has....
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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 ..