Top Circuits Page 268
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This circuit uses a dual operational amplifier (TL082) to form a voltage-controlled oscillator (VCO). With the component values shown, the output-frequency range is 100 Hz to 10 kHz when the input control voltage is between 0. 05 and 10 V. ..
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The LAS3905 series voltage regulators are ICs that contain all elements necessary for linear regulation (safe-area protection, thermal overload, and current limiting, as shown in Fig. 7-50C). Figure 7-50B shows the output voltage and tolerance for the....
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Addition of dual-triode amplifier V2 to conventional peak voltmeter reduces charging time constant while increasing available time for measuring peak value. Linearity is good up to 40 v. -M. Uno, Amplifier Improves Peak Voltmeter Response, Electronics,....
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The SL561 used in this circuit is a high-gain low-noise preamplifier designed for audio/video applications at frequencies up to 6 MHz. Figure 2-6B shows gain versus frequency for various values of C1, and Fig. 2-6C shows gain versus various values of RSET.....
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The ZN459/CP used in this circuit is a high-gain low-noise preamplifier designed for audio/video applications at frequencies up to 15MHz. Figures 2-7B and 2-7C show typical PC board layouts for the ZN459 and ZN459CP (DIP), respectively. Figure 2-7D shows....
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This circuit provides symmetrical ±output voltages, both equal to one-half the input voltage (one 9-V battery in this case). The output voltages are referenced to pin 3 (output common). The circuit will operate with other battery voltages. If the battery....
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This circuit doubles available battery voltage using an LTC1044 switched-capacitor voltage converter. The circuit will drive low-power 74-CMOS (3-to 15-V) equipment for extended periods of time from two small 1. 5-V cells. Efficiency exceeds 90% for load....
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Is capable of driving 3. w servo motor in ambient of -55 to 125ƒ, if capacitors for 125ƒ are used. Gain can be adjusted over range of 20, 000 to 80, 000 amp per amp by adjusting RF in driver circuit. Gain varies less thon 10% over operating temperature....
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Circuit generates low-frequency waveform whose amplitude is equivalent to that of unknown r-f voltage, using photochopper modulator VI-V2 as error detector. Arrangement gives seven voltage ranger from 10 my rms to 10 v rms full scale, over frequency range of....
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Measures a-c voltages between 95 and 135 v with 0. 6% accuracy while using ordinary 2% accuracy meter. Zener diodes provide reference voltage. -D. S. Belanger, Simple Circuit Increases Measurement Accuracy, Electronics, 38:22, p 69. ..
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Has high input impedance und low output impedance, to reduce droop in output voltage between pulses. Staircase is generated by pump D2-C2, which is boostrapped on output to maintain equal amplitude on each step. Circuit values shown give 10 steps with 12-V....
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The output of this circuit is a current proportional to temperature, which can be used to drive a meter for a direct readout. Alternatively, a resistor or op amp can be used to get a voltage output. The circuit is pulsed at a low duty cycle to reduce power....
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This very simple circuit is an electronic thermometer using an inexpensive silicon transistor (2N2222) as the temperature sensor or probe. The circuit provides better than 1ƒ accuracy over a 100ƒ range. An LM113 diode regulates the input voltage to 1. 2 V.....
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Acoustic thermometry is used where extremes in operating temperature are encountered, such as in cryogenics and nuclear reactors. The transducer is composed of Polaroid ultrasonic material, mounted at one end of a sealed, 6-in long Invar tube. The medium....
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CCFLs are often used to backlight the LCD displays of portable computers Such lamps require a high-voltage sine-wave drive. This circuit provides such drive and permits lamp intensity to be varied continuously and smoothly from zero to full intensity. Notice....
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The output current issensed across R8, This is delivered to the current-limit arrtplifier through R7, across which the foldback potential is developed by R6 with a threshold determined by D4. The values given limit the peak power below 20 W and shut off the....
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This circuit is an improved version of the Fig. 3-28 display, using a triangular-wave oscillator. With RA properly set, each incremental change in VIN can be detected because the glow from each LED can be made to spread gradually from one device to the next.....
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This circuit is an inverting amplifier with an output voltage swing from essentially 0 to +300 V. Any transistor can be used for Q1, provided that the breakdown voltage is greater than 300 V (because the full high voltage will be applied across Q1). Biasing....
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For a 0- to 10-V input, this circuit produces sine-wave outputs of 1 Hz to 20 kHz, with better than 0. 2% linearity. Distortion is about 0. 4% and the sine-wave output frequency and amplitude settle instantaneously to a step-input change. To calibrate, apply....
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These circuits are similar to that of Fig. 5-47, except that the circuits provide for FM or sweep modulation. Use circuit 5-50A for FM (small deviations, about ±10%). Use circuit 5-50B for a sweep range of 1000:1. As a guideline, the sweep frequency....
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An op-amp IC (741) amplifies the audio signal from MIC1, and R12 controls its gain. Audio is fed to the oscillator circuit Q1 and related components. D2 is a varactor diode. Audio fed to D2 causes FM of the oscillator signal. L1 is 1/2 turns of #18 wire on a....
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This basic ultrasonic generator can be built easily and quickly. An NE555 drives a speaker. The frequency range is 12 to 50 kHz. SPKRI is a piezo tweeter, etc. ..
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The notch filter can be added to just about any receiver to attenuate a single frequency by more Lhan 30 dB. This filter should be handy for reducing heterodynes and whistles. ..
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A wide-range voltmeter circuit. This inverting amplifier has a gain varying from -30 for the 10-mV full-scale range to -0. 003 for the 100-V full-scale range. Diodes D1 and D2 provide com-plete amplifier protection for input overvoltages as high as 500V on....
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The sine input is ac coupled by capacitor C; R1 and R2 bias the input midway between Vn and Vp, the input threshold voltages, to provide a square wave at the output. ..
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The Geiger tube needs a high voltage sup-ply which consists of Q1 and its associated components. The transformer is connected in reverse; the secondary is connected as a Hartley oscillator, and RI provides base bias. Dl, D2, C4, and C5 comprise avoltage....
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A schematic diagram for the remote analyzer is shown. The circuit is powered from a simple 5-V supply, consisting of PL1, 51, T1, abridge rectifier (comprised of Dl through D4), capacitor C1, and a common 5-V regulator, UI. Switch 51 is the on/off control....
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This battery-powered metal detector uses four exclusive-OR gates contained in the 4030 CMOS integrated circuit. The gates are wired as a twin-oscillators and a search coil serves as the inductance element in one of the oscillators. When the coil is brought....
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Simple, easily transported VSWR meter consists of high-gain amplifier, narrow-bandwidth (100-Hz) selective amplifier tuned to 1000 Hz, and variable-gain output amplifier driving low-cost VU meter. Ideal for nulling type VSWR measurements. Draws only about....
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This circuit can be used as a small beacon or marker light, amd toys or novelty items. R1 is an LDR that has‰¥10 k © dark-resistance, or a CDS photocell. C1 determines the flash rate. ..
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This circuit allows zero adjustment as well as slope adjustment. The ICL8069 brings the input within the common-mode range, while the 5 K pots trim any offset at 218 °K (-55 ƒ), and set scale factor. ..
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The device emits ultrasonic sound waves that sweep between 65, 000 and 25, 000 hertz. Designed around a 556 dual timer, one half operated as an astable nultivibrator with an adjustable frequency of 1 to 3 Hz. The second half is also operated as an astable....
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Used in high-quality stereo cassette deck operating from AC line or battery. Meter rectifier bridge is in feedback loop of opamp, to give highly linear AC/DC conversion with flat frequency/amplitude response and short voltage rise time at low cost. ..
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Circuit designed for 5-mA meter movement uses two-stage voltage ampilfer Q1-Q2 with emitter-follower output Q3 serving as impedance-matching stage AF input for S-9 reading is 25-30mV P-P and forfull scale is 50-60mV P-P Frequency response is 500 Hz to 10....
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For use with low-power transmitters with a positive keying voltage. Q1/Q2/Q3 form a switching amplifier. When the key is pressed, the collector of Q3 goes to ground, tuming on Q5 and activating IC1, an audio oscillator. Q4 drives the speaker. For use as a....
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A relaxation oscillator is used to flash an LED in the base circuit. C1 is charged slowly through R1 by the power source, then discharged periodically through R3 and the LED by the UJT. Flashing rate is determined by the supply voltage and by R1-C1`s time....
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This circuit uses a ring counter made up of Q3, Q4 and Q5. Q2 acts as an oscillator which triggers the SCRs Q3, Q4 and Q5 in sequence. When an SCR fires, a 0. 2 F ca-pacitor provides commutation, shutting off the previous stage. Triacs Q6, Q7 and Q8 control....
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Using a heatsink, the TRIAC (TR1) can handle up to 350 watts. The neon lamp, I1, won`t trip the gate until after it conducts and using R1, set the lighting wherever you want it. ..
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The circuit uses three CA3130 BiMOS op amps in an application sensitive to sub-picoampere input currents. The circuit provides a ground-referenced output voltage proportional to input current flowing through the photodiode. ..
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Uses MM5316 alarm-clock IC, originally designed to drive LCD or fluorescent displays, but modified here for LED display Diodes and batteries provide power if AC fails, with blanking of display to extend battery life. Accuracy is poor on batteries but....
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Single-capacitor circuit is reIiable over wide range of temperatures. voltages. and transistor gains. Frequency varies only by 0. 05% for supply voltage changes between 6 and 12 V. Timing can be changed with R1. R2. and C. Ducy cycle depends on ratio of R3.....
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Circuit consists of 1-2 MHz oscillator Q1, untuned mixer X1, and AF beat-note amplifier Q2. C4 is calibrated to read directly in frequency from 1 to 2 MHz, using accurate unmodulated RF signalgenerator. After calibration, unknown RF signal input frequency is....
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The electromagnetic ring launcher is comprised of four subcircuits: a clock circuit (built around U5, a 555 oscillator/timer configured for astable operation), a count-down/display circuit (built around U3), a 74190 synchronous up/down counter with BCD....
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Programmed Signetics 8223 256-bit PROM is used as alphameric display having five 7-segment digits connected to form alphameric simulation of abbreviations for second, millisecond, microsecond, hertz, kilohertz, and megahertz as SEC, SEC-3, SEC-6, H2, H2 3,....
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When button S12 (#) is pressed, a positive voltage fed through R1 appears at the base of transistor Q1, turning it on. When Q1 is conducting, pin 1 of U1 is brought to ground (low) or the battery`s egative terminal. With pin 1 low, two things occur: Pin 8 of....
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With transistor switching circuit shown for RCA SG2007 laser diode, pulses as short as 10 ns are possible at repetition rates above 100 kHz. Used in optical communication system in which fiber bundle or singlefiber is attached directly to laser pellet. -J.....
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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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This circuit tums a sine wave into a square wave. It is comprised of a single 2-input NAND Schmitt trigger that`s conftgured as an inverter with a trigger level adjustment at its input. As the input voltage rises above the gate`s trigger point, the output....
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A TMOS MTM7N45 (Q2) is used as a series pass element in a linear high voltage supply that accepts +275-V unregulated and produces 250 V regulated with foldback current limiting. A 15-V zener, D1, provides the dc reference for operational amplifier U1, whose....
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Addition of diode limiter and positive feedback resistor to UAF41 universal active filtrer gives precision quadrature oseillator. -Y. J. Wong, Design a Low Cost, Low-Distortion, Precision Sine-Wave Oscillator, EDN Magazzine, Sept20, 1978, p 107 113. ..
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Values shown for high-stability variable-frequency oscillator give operation in 10-MHz range. Stable supply voltage is essential. Use silver mica capacitors in gate circuit for maximum stability. -E. M. Noll, FET Principles Experiments, and Projects, "....
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This FETVM replaces the function of the VTVM while at the same time ridding the in-strument of the usual line cord. In addition, drift rates are far superior to vacuum tube circuits allowing a 0. 5 volt full scale range which is impractical with most vacuum....
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In operation, the alarm circuit allows a 0-47 second time delay, as determined by the R1/C1 combination, after the switch is armed to allow the vehicle`s motion sensor to settle down. This allows you time to get a bag of groceries out of the trunk and not....
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Power op amps provide accurate speed control for dc motors. The circuit provides bidirectional speed control. The amplifiers` push-pull configuration ensures a full rail-to-rail voltage swing (minus the output stages` saturation drops) across the motor in....
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This display uses ten LED`s to display a voltage range from 10. 5 to 15 volts. Each LED represents a 0. 5-volt step in voltage. The heart of the circuit is the LM-3914 dot/bar display driver. Trimmer potentiometer R5 is adjusted so that 7. 5 volts is applied....
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Rectifted and filtered voltage from the 24 Vac transformer is applied to the LM723 voltage regulator and the npn pass transistor set up for constant current supply. The 470 ohm resistor limits trickle current until the momentary pushbutton (S2) is depressed,....
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The signal from a synchro receiver or a variable resistive cam follower (potentiometer) is boosted by operational amplifier U1, whose output swing is limited by back-to-back zeners D3 and D4. The signal is then applied to operational amplifiers U2 and U3,....
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In the absence of radiation, no current is drawn. At normal background radiation levels the power consumption is extremely low. The instrument may be left on for several months without changing batteries. In this way the detector is always ready to indicate....
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National LM195 power transistor is turned on and off once per second for flashing 12-V lamp. Current limiting in LM195 prevents high peak currents during turnon even though cold lamp can draw 8 times normal operating current. Current-limiting feature....
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Standard Colpitts oscillator Q1 with emitter-follower Q2 gives dependability and adequate isolation from later stages Zener regulation provides stability even with weak battery Output is about 0. 7 VRMS. Low-level parasitic oscillation may occur about 150....
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This transmitter sends an FM signal in the 88-to 108-MHz range, with a tone of 19 kHz. This can be used to activate the FM MPX pilot carrier indicator, which can be interfaced to external devices. L4 is for use with a 15 CM wire antenna. L1 is 9 turns of #26....
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When power is applied to the circuit, SCR1 is off, so there is no bias-current path to ground; thus, LM317 acts as a current regulator. The LM317 is connected to the battery through steering diode D1, limiting resistor R1, and bias resistor R2. The steering....
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Based on the LM733 or NE592, the preamp shown has a bandwidth of 100 MHz. The FET inputs provide about 1-M © input impedance. Q4, Q5, and IC2 provide signal conditioning. ..
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The Biquad consists of two successive integration stages followed by an inverting stage. The entire group has a feedback loop from the front to the back consisting of R1 which is chiefly responsible for controlling the center frequency, ‰o. The first stage....
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Two NAND gates are used for the oscillator, and two as the control. If the two-tone speed needs to be altered, the 220 F capacitors can be changed (larger for slower operation). If the frequency of the oscillator is to be changed, the 0. 2 and 0. 1 F....
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The signal starts at a low frequency, rises for about 1. 15 seconds to a high frequency, ceases for about 0. 35 seconds, then starts rising again from a low frequency, and so on ad infinitum. ..
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IC1a and IC1b are wired as a slow astable multivibrator and IC1c-IC1d are wired as a fast astable. Both are "gated" types, which can be turned on and off via PB1. The output of the slow astable modulates the frequency of the fast astable, and the output of....
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741 opamp is connected as audio oscillator with Radio Shack 276-677 photocells in feedback circuits. When light strikes PC1, its resistance decreases and frequency of audio tone in headphone decreases correspondingly. When light strikes PC2, which is....
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Low light on cadmium sulfide photocell (Radio Shack 276-116) produces series of clicks in miniature 8-ohm loudspeaker. As light increases, clicks merge into audio tone that increases in frequency as light intensity increases. Can be used for classroom....
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IC1, an Intersil ICL7106, contains an a/d converter, a 3 1/2-digit LCD driver, a clock, a voltage refer-ence, seven segment decoders, and display drivers. A similar part, the ICL7107, can be used to drive seven segment LEDs. The probe body is a five-inch....
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U1a is an oscillator and U1b the measurement part of the circuit. It converts unknown capacity into a pulse-width modulated signal the same way an automotive dwell meter works. The meter is linear so the fraction or percentage of time that the output is high....
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A Wien bridge oscillator produces sine waves with very low distortion level. The Wien bridge oscillator produces zero phase shift at only one frequency (f=1/2 RC) which will be the oscillation frequency. Stable oscillation can occur only if the loop gain....
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Mullard TCA240 dual balanced modulator-demodulator provides suppression of carrier frequency at output, as required for SSB or DSB operation of transmitter. Bias resistor R7 is adjusted for minimum carrier output to correct imbalance. Can be used as....
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AF modulating signal is applied to gates of matched FETs in push-pull through T1 having accurately center-tapped secondary, and RF carrier is applied to sources in parallel through C3. Carrier is canceled in output circuit, leaving two sidebands. R3 is....
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Uses controlled variation of amplifier bias current IABC in CA3080A variable opamp to obtain effective gain control of signal. Variations in amplitude of modulating voltage Vm change bias current through Rm to give amplitude modulation of carrier. -"Circuit....
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With DC control voltage of 5 mV to 5 V, circuit controls frequency of both square and triangle outputs with good linearity. Peak value of triangle output is precisely set at 2. 44 V and 0 V by reference voltages at noninverting inputs of comparators.....
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One can transform an ordinary binary counter, such as a 7493, into an up/down counter with mode control by adding XOR gates 7486 to the counter`s outputs. The circuit counts up when the DN/UP line is low and down when the DN/UP line is high. To use the 7493....
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Input voltage range of 0-10 V is converted to proportional frequency at output of optoisolator with high linearitv bv RM4151 converter used in combination with RC3403A quad opamp that provides. functions of inverter, integrator, regulator, and LED driver -....
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The circuit consists of ICM7208 seven-decade counter U1, ICM7207A oscillator controller U2, and CA3130 biFET op amp U3. IC UI counts input signals, decodes them to 7-segment format, and outputs signals that are used to drive a 7-digit display. IC U2 provides....
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By using the preamplifier with a short length of shielded cable and clip leads, signals that generally could not generate a readout, generate precise and stable readouts on the counter. The DPDT switch is used to bypass the circuit when amplification is not....
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A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance RS, of 14 ©, oscillates at its third harmonic. The diode clamp D1 and D2 provides a constant amplitude control. The transistor operates continuously in a linear mode....
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This inverter can deliver high-voltage ac or dc, with a rectifier and filter, up to several hundred volts. The secondary and primary of T1-a 12. 6 to 440 V power transformer, respectively-are reversed; e. g. , the primary becomes the secondary and the....
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The zener provides a constant voltage of 20 V to unijunction transistor Q1, except at the end of each half-cycle of the input when the line voltage drops to zero. Initially, the voltage across capacitor C1 is zero and capacitor C2 cannot charge to trigger....
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This circuit`s frequency of oscillation increases directly with light intensity. The greater the light intensity, the higher the frequency of the oscillator. The 555 timer operates in the astable oscillator mode where frequency and duty cycle are controlled....
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Uses National have sound. MM57100 TV game chip to provide logic for generatingbackgrounds, paddles, ball, and dig ital scoring Circuit generates all necessary timing (sync, blanking, and burst) to interface with interface directly to antenna terminals of....
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This is a schematic and block diagram of a 2-MHz frequency counter. It uses and LSI counter/display driver, LCD readout, and a, few logic chips for timebase and timing pulse circuitry. Q2 and Q3 form a signal (input) amplifier. The circuit contains a crystal....
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The ROMs or PROMs must have the correct code for converting the data from the NE5037-used as address for the ROMs or PROMs-to the appropriate segment driver codes. The displayed amount could easily be converted to degrees Fahrenheit, °F, by the controller of....
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A simple op amp and silicon diode are the heart of the temperature-to-voltage converter that will permit you to use an ordinary voltmeter-either analog or digital-to measure temperature. User adjustments make it possible for a reading of either 10 mV or 100....