Top Circuits Page 7
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This circuit shows a typical over/under-voltage fault monitor for a single supply. The upper trip points, controlling OUT 1, are centered on 5.5 V with 100 mY of hysteresis Wu = 5.55 V, "L = 5.45 V); and the lower trip points, controlling OUT 2, are....
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This circuit provides accurate full-wave rectification. The output impedance is low for both input polarities, and the errors are small at all signal levels. Note that the output will not sink heavy currents, except a small amount through the 10-K!J....
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817V The outputs in this circuit are independently variable and can be loaded unsymmetrically. The output voltage remains constant, irrespective of load and changes. By varying potentiometers R2 or R6, the output voltages can be conveniently set.....
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In this application, the Vl-7660 is connected as a voltage splitter. Note that the normal output pin is connected to ground and the normal ground pin is used as the output. The switches that allow the charge pumping are bidirectional; therefore, charge....
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Ul is a dual voltage comparator with open collector outputs. The A side is an oscillator operating at 100kHz, and the B side is part of the regulation circuit that compares a fraction of the output voltage to a reference generated by zener diode D2. The....
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This converter delivers up to 50 mA from a 6-V battery with 78% efficiency. This flyback converter functions by feedback-controlling the frequency of inductive flyback events. The inductor"s output, rectified and filtered to de, biases the feedback loop to....
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This nonisolated, unregulated, minimum component converter fills the void between low-power zener regulation and the higher power use of a 60-Hz input transformer. It is intended for use where)"er a nonisolated supply can be used safely. The circuit....
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The buck-boost configurationnf the MAX634 is well suited for dual output de-de converters. Only a second winding on the inductor is needed. Typically, this second winding is bifilar-primary and secondary are wound simultaneously using two wires in....
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Many devices operate from a car"s 12-V electrical system. Some require 12 V; others require some lesser voltage. An automobile battery"s output can vary from 12 to 13.8 V under normal circumstances. The load requirements of the device might vary. This....
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Regulation is provided by taking the rectified output of the sense winding and applying it as a bias to the base of Q2 via zener Dl. The collector of Q2 then removes drive from the gate of Ql. Therefore, if the . output voltage should increase, Q2 removes....
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For systems with only one power supply, two op amps act as instrumentation and buffer amps. The OPA111..
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This bridge will measure inductances from about 1 to 30 at a test frequency of 5 mHz. A 365-pF AM-type tuning capacitor ..
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This circuit was used to produce a variable negative voltage for contrast control of an LCD displa..
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A common power-supply requirement involves converting a 2.4- or 3-V battery voltage to a 5-V logic suppl..
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Used on an amateur or experimental radio beacon, the above ID circuit will generate any callsign or message program..
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The noninvertiiig terminal of the op amp is grounded, and the circuit uses the voltage at the inverting t..
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This circuit provides a unique solution to a common system-level power distribution problem: When the su..
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IC1 is a switching regulator that generates a 45-kHz signal that drives the gate of MOSFET Ql. Dl, D2, an..
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Laptop computers often use large-screen LCDs, which require a variable and a negative supply to ensure maxi..
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Optically isolated SMPS and dc-to-dc converters face the variance of output voltage owing to the change of transmission c..
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Many power-factor-correction circuits use a boost converter to generate a regulated dc output voltage from the ac line inp..
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By coupling two back-to-back diodes in series with an ac power circuit, a voltage of about 1.4 Vpp can be obtained. This..
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The dc-dc converter substitutes a voltage tripler in place of the external inductor and the diode that"s typically as..
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Most small portable radios require a 3-V supply, which is normally provided by two AA or AAA batteries..
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This bridge circuit is intended for those cases where two unequal supply voltages are required. The lower voltage is obtai..
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A current source that attains a resolution as low as 10 pA is useful in applications where a precise, low-value ..
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This circuit provides a precision voltage source that can be adjusted through zero to positive a..
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A fixed current flows through any load that is connected between the positive supply and Ql"s collector. The noninverting..
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This supply uses an SGS-Thomson UC3842 IC in an off-line flyback regulator, providing + 5 V at 4 A..
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The simple diode network can stabilize the voltage supplied to CMOS circuitry from a battery. D1 and D2 must have a c..
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A dc-dc converter using a 74HC04 drives Tl. Tl is a ferrite-core transformer using a Fair-Rite, Inc. P/N 597..
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This high-voltage pulse supply will generate pulses up to 30 kV. Ql and Q2 form a multivibrator in conjunction wi..
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This power supply uses an LM317J adjustable regulator and an MJ2955 pass transistor. Ql and U2 as..
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Intended as a replacement for generally poorly regulated "wall-type" ac/dc adapters, this circuit offers superior p..
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This supply can serve as a battery eliminator for various devices (such as tape recorders, small..
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By selecting capacitors, various voltages can be obtained from this supply. Notice that C2 through C7 must be ..
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In this circuit, a full-wave bridge is switched to a full-wave center tap to reduce regulator dissi..
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Many applications require highly efficient negative-voltage post regulators with low dropout voltage ..
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This regulator provides 12 V at 1 A out with an input voltage of 8 to 20 V. Output voltage can be changed by c..
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This fixed 1-mA current source delivers a fixed current to a load connected between Ql"s collector and ground; the ..
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The special characteristic of this regulator is that the output voltage can be adjusted down to 0 V. The regulation is pr..
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The ICL8212 is connected as a programmable zener diode. Zener voltages from 2 V up to 30 V can be programmed by suitably..
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The circuit consists of eight cascaded identical cells, each ccll being a dc-controlled active phase shifter. Because the dc control is common for all shifters, the circuit is adjusted by trirtuiiing RA so that the phase difference between and Vi is zero.....
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The value of the design lies in the use of IC1, an LM317HVK adjustable s.eries-pass voltage regulator, for broad-range performance remainder supplies voltage-setting and current-limiting functions. The input to ICI-comes from the output of BR1, which is....
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With this unique logic-power-converter design (see the figure), a switchable 3.6 or 5 V at 200 inA can be attained by using four AA cells. The supply incorporates a MOSFET switch that can switch to a lithium backup battery, providing a 3.4-V output when the....
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One LTC 1149 synchronous switching regulator can deliver both 3.3- arid 5-V outputs. The design`s simplicity, low cost, and high efficiency make it a strong contender for portable, battery-powered applications. The circuit described accepts input voltages....
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This regulated power supply consists of step-down transformer Tl, a full-wave rectifier bridge (D1 through D4), and a filtering regulator circuit made up of Cl, C2, Rl, R2, R8, D5, and Ql, When 120 Vac is provided, the neon-lamp assembly LI lights up, and....
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This 0- to 12-Vdc variable power supply uses an IC voltage regulator and a heavy-duty transformer to provide a reliable dc power supply. Looking at the schematic shown, you can sec that transformer Tl has a 120-V primary and a 28-V secondary. Filtered dc is....
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This circuit, can deliver 3 A or more and a maximum dc voltage ol` a little over 20 V. It is designed around the readily available LM317T adjustable 3-terminal regulator and has a pnp power transistor to boost the current output. The transformer has an 18-V....
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Although intended to power a 100-W low-frequency amplifier, this power supply should handle many mono or stereo amplifiers in the medium power range..
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A dual audio amplifier that will deliver 50 W per channel is shown in the schematic. It includes preamp and tone controls, and also includes a headphone amplifier. ..
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It`s common knowledge that when working with single-supply op amps, implementing simple functions in a bipolar signal environment can be difficult. Sometimes additional op amps and other electronic components are required. Taking that into consideration,....
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Large input-to-output voltage differentials, caused by wide input voltage variations, reduce a linear regulator`s efficiency and increase its power dissipation. A switching preregulator can reduce this power dissipation by minimizing the voltage drop across....
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A 9-V wall adapter supplies Vm. IC2 contains a low-battery detector circuit that senses l7IN by means of R6 and R7. The detector output Cpin 7) drives an inverter (Ql), which in turn drives the shut-down inputs Ic of 1C1 and SHDN of IC2. These inputs have....
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This low-power converter will supply about 100 mW of dc to a load and it is useful to isolate or derive dc voltages. It operates at around 200 kHz. LI is wound on a 22-mm diameter 13-mm high pot core with #32 magnet wire. The primary is 80 turns and the....
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The circuit will provide 3 preset currents which will remain constant despite variations of ambient temperature or line voltage. ZDl produces-a temperature stable reference voltage which is applied to the noninverting input of ICl. 100% feedback is applied....
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A simple 120 V: 24 V, center-tapped control transformer and four additional components can do the job. This circuit outputs a clean 200 V pk-pk square wave at 60 Hz and can supply up to 20 W. The circuit is self-starting and free-running. If Q1 is....
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This is a simple, precise voltage-controlled current source. Bipolar supplies will permit bipolar output. Configurations featuring a grounded voltage- control source and a grounded load are usually more complex and depend upon several components for....
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This regulator delivers 90% efficiency at 12-V input, 5-V output. It uses an LT1158 and LT1431 by Linear Technology, Inc. High efficiency is obtained by synchronously switching two power MOSFETs in a step-down switching regulator...
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Input, voltages can range from 8 V to 30 V. The load range on the 5 V is 0,05 A to 5 A while the 3.3-V load range is 0.1 A to 1 A. The circuit is self-protected under no-load conditions. Over all load and line conditions, .including cross regulation, the....
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This voltage-regulator/cuiTent-liimter combination can be made from two 7805 regulators as shown. Rl, R2, and R3 shouldbe selected for a 5-V drop at the maximum allowable currant limit. SI selects one of the three current values. Do not forget that Ul....
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Using two 12-V filament or power transformers, an impromptu isolation transformer can be made for low-power (under 50 W) use in testing or servicing. SOI is an ordinary, duplex ac recept-able. ..
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By adding a flyback winding to a buck-regulator switching converter (see the figure), wliich is essentially a 5-V supply with a 200-mA output capability, a 12-V output ) can be produced. The flyback winding on the main inductor (forming transformer Tl)....
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I tried to design a timer that would do everything it needed to do but with the smallest number of pieces and simplest mode of operation. It only needs the PIC, a four digit LED display, one other IC, a resistor network, one pushbutton switch and a....
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The preamplifier was designed to signal sources such as low-impedance moving coil cartridges (MC) on turntables
high fidelity (and yet still there). The impedance of the amplifier is 100 W. To keep the noise levels low, three double-type transistors MAT03....
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The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
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Signals of identical frequency are applied to sync input (Pin 6) and to the demodulator input (Pin 4), respectively, the demodulator functions as a phase detector with output dc component being proportional to phase difference between the two inputs. The....
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Simple frequency limit detectors providing a GO/NO-GO output for use with varying amplitude input signals may be conveniently implemented with the ICL8211/8212. In the application shown, the first ICL8212 is used as a zero-crossing detector. The output....
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The MC1596/MC1496 makes an excellent SSB product detector. This product detector has a sensitivity of 3 microvolts and a dynamic range of 90 dB when operating at an intermediate frequency of S MHz. The detector is broadband for the entire high frequency....
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The circuit will provide a dc output equal to the rms value of the input. Accuracy is typically 2% for a 20 Vpp input signal from 50 Hz to 100 kHz, although it"s usable to about 500 kHz. The lower frequency is limited by the size of the filter capacitor..
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Detector uses three sections of an L144 and a CMOS NAND gate to make a very low power voltage monitor. The 1 MO resistors Rl, R2, R3, and R4 translate the bipolar ±10 V swing of the op amps to a 0 to 10 V swing acceptable to the ground-referenced CMOS logic..
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The detector circuit is made up a two-amplifier multiple feedback bandpass filter followed by an ac-to-dc detector section and a Schmitt Trigger. The bandpass filter (with a Q of greater than 100) passes only 5Q0 Hz inputs whch are in turn rectified by Dl....
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The timing cycle is continuously reset by the input pulse train. A change in frequency, or a missing pulse, allows completion of the timing cycle which causes a change in the output level. For this application, the time delay should be set to be slightly....
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This detector is useful in sine wave squaring circuits and A/D converters. The positive input may either be grounded or con-output nected a nulling voltage which cancels input offsets and enables accuracy to within microvolts of ground..
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This circuit is useful for signal-processing sonar data recorded on an instrumentation-quality analog tape recorder. The envelope detector utilizes ready available parts, and furnishes accuracy beyond 100 kHz. Two LM301 op amps connected as precision....
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The circuit can be used to tell whether or not an input signal is within a certain frequency range. The device consists of three !Cs, a dual monostable multivibrator, and two dual D-type flip-flops. The signal whose frequency is in question is fed to the....
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The 555 is a monostable that wants a negativegoing trigger. If the pulse you"re feeding it with is positive-going, you can run it through an inverter made up of either an inverting gate or, if you"re tight on space, a single transistor. Both ways are....
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This circuit requires low noise, low and stable offset voltages, high open loop gain, and high speed. These requirements are met by the HA514 7. The standard variations of this circuit can easily be implemented using the HA-5147. For example, hysteresis....
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Requiring only two ICs to monitor a train of positive pulses, this circuit produces a single positive output pulse for each input pulse whose duration is either too long or too short. You specify the minimum and maximum limits by adjusting the trimming....
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This circuit will detect a missing pulse or abnormally long spacing between consecutive pulses in a train of pulses. The timer is connected in the monostable mode. The time delay should be set slightly longer than the timing of the input pulses. The timing....
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The peak detector tracks and holds, using the charge-storing ability of a capacitor, the highest output voltage from a transducer. Initially, the voltage on the inverting input of the comparator is at ground level. As a small voltage (0-5 V) is captured by....
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This circuit can detect the positive peaks for signal frequencies higher than 5 MHz. It yields ±1% accuracy for 400 mV to 4 V pk-pk signal amplitudes on sine, square, and triangular waveforms. The Am685 comparator output increases whenever VrN is a....
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The tracer receiver is a stereo audio amplifier/detector circuit operating near 1 kHz. Inductors Ll and 12-hand-wound coils, consisting of 200 turns of #26 wire on 2-inch ferrite cores-are tunea to the operating frequency of the amplifier/detector. The....
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This circuit passes the input signal at unity gain, either unchanged or inverted, depending on the digital control input. A buffered input is shown, since low-source impedance is essential. Gain can be added by modifications to the feedback networks.....
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The output of the detector contains a term related to the cosine of the phase angle. Two signals of equal frequency are applied to the inputs. The frequencies are multiplied together, producing the sum and difference frequencies. Equal frequencies cause....
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Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope"s three-pronged power plug. You can avoid this problem by using the ground-noise tester shown. Powered by two 9-V batteries, the circuit....
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The unit is constructed around a balanced-bridge circuit. using both capacitance and inductance. The bridge consists of capacitors C2 and C3, and the center-tapped winding of Tl. One end of the bridge is coupled to ground by C4, while capacitance changes....
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This circuit detects frequency variation above or below preset limits. IC1 is a binary counter docked at FcLK· The outputs are comparea with switch preset values by IC2 and IC3. The input signal, which must be a positive-going pulse, is used to reset IC1.....
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This circuit de-energizes a normally energized relay if the input voltage goes above or below two individually set voltages. The transistor driving the relay is normally turned on by R4, so the relay is normally energized. Ifthe cathode of Dl or D2 is....
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This simple window detector uses only half of a 7400 quad NAND gate plus four resistors, chosen so that the voltage at point A exc.,eds the voltage at point B for any input voltage. With no input applied or when VIN is at ground, the output of gate Gl is....
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Sensing short circuits in equipment that performs under water is especially critical, but Fig. 20-4"s wet-mat..
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Using the principle of capacitance between two plates this circuit senses when more than one sheet of paper goes betwee..
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A 0-to-5 V input drives the negative input of LM392 comparator if reset (pin 12) if DC4060BE is pulled high then low, all out..
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The output goes high when the supply falls below a value determined by zener diode Dl. If Dl is a 5.6-V zener, the op..
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This circuit detects the 1050-Hz tone sent by the NOAA (National Oceanic and Atmospheric Administration) Weather..
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Many applications require analog signals to be sensed and digital signals to be controlled. A way to detect these p..
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An analog signal requires about 100 ns to propagate through the HA-5320. For time-varying signals, this assures a voltage dif..
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Useful for checking TV remote controls, IR-based alarm systems, and IR sources, this circuit causes LED1 to turn on for two sec..
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In this open-loop design, the detector diode is Dl, and a level shifting or compensating diode is D2. Load resistor RL is connected to -5 V, and an identical bias resistor RL is connected to -5 V, and identical bias resistor RB is used to bias the....
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This closed-loop peak detector circuit uses a Schottky diode inside feedback loop to obtain good accuracy. The 20- resistance RQ isolates the 0.01- load and prevents oscillation. The dc value is read with a DVM. At a low frequency, the error is small and....