New Circuits Page 249
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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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This very special mains-operated dimmer for domestic or industrial lights is not available in proprietary form: it ena..
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As shown, a 555 timer (Ul) is configured as an astable multivibrator (oscillator) with a 400:1 duty cyc..
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Circuit for applying a dc-coupled FM or PPM to a 555 configured as an oscillator. IC-1 - Motorola MC-1374P. IC-2 - National LH0002C. L1, L2 - Mouser Electronics #421IF200. C1. C2 - Silver mica, 300 pF. All 0.1 uF cap., ceramic disc, 16V. C3 - 100 uF, 10 V,....
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Using a single chip LM324 can, with active R-C networks, reduce the size of a 3-phase waveform generator, and prove useful in compact and stable 3-phase inverters. One quarter of an LM324 is used as a Wien bridge oscillator generating a pure sinusoidal....
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This amplifier is so high quality that it would be understatement to speak HIFI amplifier. HIFI-confirmed-Finland the frequency response must be direct and distortion <1% 20-20 kHz. Our articles power amplifier circuit again meets the above requirements for....
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Very simple, versatile modular design. The purpose of this circuit was to create a ring in which LEDs or Lamps illuminate sequentially. Its main feature is a high versatility: you can build a loop containing any number of LEDs or Lamps, as each illuminating....
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The single speaker amplifier circuit uses current feedback, rather than the more popular voltage feedback. The feedback loop is from the junction of the speaker terminal and a 0.5-0 resistor, to the inverting input of the NE5534. When the input to the....
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An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual 4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13,....
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This project can be used for many different purposes. Probably the most used application would be to interface to any electronic project that requires a keypad. There are several ready made keypads on the market, but those work with matrix connections and....
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The Multimeter Clock consists of three multimeters, the first meter displays hours, the second displays minutes and the last displays seconds. A 16F628A PIC microcontroller keeps track of time and outputs a calculated current to each meter to display the....
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This circuit provides a low cost and reliable method of testing zener diodes. RVl can be calibrated in volts, so that when LED 1 just lights, the voltage on pins 2 and 3 are nearly equal. Hence, the zener voltage can be read directly from the setting of RVl.....
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The circuit monitors and displays a digital signal"s duty cycle and provides accuracy as high as ±1%. Using switch S2, you can choose a frequency range of either 250 Hz to 2. 5 kHz at ±1% accuracy or 2 kHz to 50 kHz at ±10% accuracy. The common-cathode....
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This encoder uses a single contact per key keyboard and provides all other switching functions electronically. The diode connected between terminals 8 and 15 prevents the output from goitrg more than 1 V negative with respect to the negative supply Vss.....
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The preamp circuit is completely conventional, and by necessity is AC coupled throughout. The artificial earth is derived by two resistors (R1 and R2), which will set the "earth" at exactly 1/2 the supply voltage. This is nominally 13.8V in all cars, since....
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A heat-sensitive sensor can be used to construct a direction detector. Such a sensor reacts to all an..
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This is a simple Surround Processor with the degital delay method. This audio processor is not using any special function ICs that difficult to get parsonaly, and desined in only general purpose ICs. Of course the Digital Delay Block of A-D, D-A and delay....
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This simple Linear circuit provides continuously variable regulated current (~25-400mA) from a 4-6 Volt source. I chose a linear design for simplicity, reliability, ease of repair, and to avoid switching EMI in my Cave Radios. The circuit requires only....
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The F — V input frequency is locked to the V — F output because the LTClG43's clock is common to both sections. The F — V's reference is used as one input of the multiplier, while the V — F furnishes the other.
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This adapter circuit, based on a dual four-channel analog multiplexer handles digital signals to at least 1 MHz, and analog signals at least through the audio range. The dual multiplexer's upper half selects one input for display. The lower half generates a....
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This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. Let us see what we have....
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Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer. The basic formula is P=VI and between input....
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This circuit is a dual voltage regulated power supply, +12, -12, 0 volt. It uses the 7812 and 7912 regulators. You need a 18VCT, 1A transformer at input...
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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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Once i had my SX-64 repaired i wanted to do something cool with it. I learned about people who added ethernet interfaces to their C64 and since i had some spare ones of the required ethernet chips, i decided to build the net64 cartridge. See the image above....
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This circuit combines two LTC1043s with a based humidity transducer in a simple charge-pump based circuit. The sensor specified has a nominal 400 pF capacitance at RH = 76%, with a slope of 1.7 pF/% RH. The average voltage across this device must be zero.....
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This circuit is for the purpose of monitoring automotive lighting. Two special ICs are available from Telefunken that ar..
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The circuit"s frequency oscillation is /=2.8/ [Cix(/i + i2)]· Using the values shown, the output frequency can be varie..
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I wanted a robust, portable, compact antenna usable for horizontal and vertical polarisation to take along with my FT-817 when I go on vacation, camping etc. I also wanted the dipole to cover the VHF and UHF bands and if possible with some gain! As everybody....
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Stepper motors are useful in many consumer, industrial, and military applications. Some, such as personal-transportation systems, require precise speed control. Stepper-motor controllers can be simple (Figure 1), but they require a variable-frequency square....
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The system utilizes the H21A1 and a chopper disc to provide superior speed regulation when the dynamic characteristics of the motor system and the feedback system are matched to provide stability. The tachometer feedback system illustrated was designed....
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The NPD5566 monolithic dual is used in a differential multiplex application where Rds(ON> should be closely matched) for the monolithic dual tracks at better than ±1% over wide temperature ranges (-25° C to +125° C), this makes it an unusual but ideal....
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This circuit is intended to indicate the power output level of any audio amplifier. It is simple, portable, and displays three power levels that can be set to any desired value. IC1A is the input buffer, feeding 3 voltage comparators and LEDs drivers by....
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The low output impedance of a closed loop op amp gives ideal line-noise immunity, while the op amp's offset voltage drift provides a temperature sensor. Using the op amp in this way requires no external components and has the additional advantages of a....
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A 100 second delayed turn ON relay RL1 switch, if plug power +12V in circuit. In Fig.2 see a two range 6-60 second and 1-10 minute auto turn off relay timer circuit, with 555...
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The circuit shown above can be used to control a unipolar stepper motor which has FOUR coils (I've swiped it off an old fax machine). The above circuit can be for a motor current of up to about 500mA per winding with suitable heat sinks for the SL100. For....
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The first application has to be a stereo power amp, since that`s what I built using two prototype modules. The reasons for this choice are twofold ... a good high powered stereo amp is always useful, and it was important to be able to assess the sound....
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Sometimes, for a variety of reasons, it would be nice to vary the width of the `sound stage` when listening to stereo recordings. Although technically this is anything but hi-fi, it is a useful addition to PC speakers, or even for the music centre in the....
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This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
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This circuit blanks the CRT starting just before retrace begins. Since the CRT sits at a -1200 volt potential, the blanking circuit must also be based at -1200 volts. Note the capacitors, C40, C41, and C43 which allow the gates that drive the intensity grid....
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Many a times one needs an ex- tra telephone ringer in an ad- joining room to know if there is an incoming call. For example, if the telephone is installed in the drawing room you may need an extra ringer in the bedroom. All that needs to be done is to....
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The light-sensitive CDS cell R8 configured in a bridge circuit with IC1 as a comparator causes ICl`s output to go high when light strikes the CDS cell R8, triggering SCR1...
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This circuit can produce up to 1 W of audio power to drive a speaker or horn. When the CDS cell is struck by light, its resistance decreases thus activating NOR gate (a) thereby causing (a) and (b) to produce a low-frequency (10-Hz) square wave. This pulses....
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This circuit was developed since a number of visitors of this website requested a timer capable of emitting a beep after one, two, three minutes and so on, for jogging purposes.
As shown in the Circuit diagram, SW1 is a 1 pole 9 ways Rotary Switch. Setting....
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The device remains dormat (in an off condition) until some sound causes it to tum on. The input stage is a 741 operational amplifier connected as a noninverting follower audio amplifier. Gain is approximately 100. To increase gain raise the value of R2..
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The two-chip circuit in Figure 1 provides fan control and overtemperature warning and shutdown signals to protect systems from excessive heat. The circuit monitors the temperature of the pc board and the die temperature of a CPU, an FPGA, or another IC with....
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The JFET Pierce oscillator is stable and simple. It can be the clock of a microprocessor, a digital timepiece or a calculator. With a probe at the output, it can be used as a precise injection oscillator for troubleshooting.
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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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A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps. Simple to build, simple to make, nothing too complicated here. However you must use the CMOS type 555 timer designated the 7555, a normal 555 timer will not work here due to the....
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The circuit uses an ICM7213 precision one minute/one second timebase generator using a 4.1943 MHz crystal for generating pulses counted by an ICM7217B. The thumbwheel switches allow a starting time to be entered into the counter for a preset-countdown type....
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Audio Jammer Noise generator for detector audio circuit..
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The pulse repetition rate is selected by positioning SI to the desired position and the rate remains essentially constant when the resistors which determine on-period and off-period are adjusted.
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There is no need to resort to complex circuitry if what you are looking for is a simple power flasher. The light will flash at around 1Hz with a 100W bulb at a duty cycle of 50%. The max. load that can be driven with this circuit is 200W and if you wish to....
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This project is based almost directly on the typical application circuit in the National Semiconductor specification sheet. You can also use the TDA2050 (from SGS-Thompson), which has almost identical performance and (remarkably) the same pinouts! As it....
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This is the circuit of a 500 watt linear amplifier, based upon a design by Frits Geerligs, PA0FRI. The circuit uses four PL519 TV line output valves in a very simple circuit that will deliver over 450 watts at 3.5 MHz (350 watts at 30 MHz). PL519 (40KG6A) is....
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This diagram shows a high speed data acquisition system with 8 differential inputs and 12-bit resolution using the AM-543. If the control logic is timed so that the Sample-Hold-ADC section is converting one analog value while the mux-amplifier section is....
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An RF input is applied to the primary of Tl, which applies equal amplitude, opposite phase RF drive for output FETs Ql and Q2. With no AF modulation at points A and B, the opposite phase RF signals cancel each other and no output appears at the 50 V output....
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This is a second-order, low-pass filter with programmable cutoff frequency. This circuit should be driven from a low-source impedance since there are paths from the output to the input through the unselected networks. Virtually any filter function which....
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This combination sync stripper and universal video interface can solve a lot of problems for you, including Super-Nintcndo-to-anything interfacing, video overlay and scope TV frame locking. Kits, fully tested units, and custom cable assemblies are available....
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There is no PCB since there are no components to mount on one. the object was to create a source of Ultr Violet light as fast as possible. The UV tubes I bought from a lighting shop for use with handheld battery lamps using 4-watt tubes. the tubes are white....
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The circuit will regulate the rms output voltage across the load (a projection lamp) to 100 volts ±2% for an input voltage between 105 and 250 volts ac. This is accomplished by indirectly sensing the light output of lamp LI and applying this feedback signal....
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The LM383 is an audio-power amplifier that is capable of producing up to 8 W of audio output. R1 is essentially a load resistor for the hand-held transceiver"s audio output. R2 can be composed of two fixed resistors in a 10:1 divider arrangement, but using....
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The circuit has a frequency response that ranges from 100 Hz to 3 MHz; the gain is about 30 dB. Field-effect transistor Ql is configured in the common-source self-biased mode; optional resistor R1 allows you to set the input impedance to any desired value.....
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This tachometer can be set up for any number of cylinders by linking the appropriate timing resistor as illustrated. A 500 ohm trim resistor can be used to set up final calibration..
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The 1381 solar engine uses a 1381* voltage detector (a.k.a., a voltage supervisor) IC to drive a voltage-based (type 1) solar engine. The 1381 is normally used to reset CPUs and Micros when the power supply drops too low for reliable operation. So 1381s....
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Many systems use watch-crystal-based, 32.768-kHz oscillators. In battery-powered designs, the 32-kHz oscillator may consume a fairly high percentage of the total power budget. Reduced power consumption equates to longer battery life, smaller batteries, and....
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The TMP03* is a complete temperature data-acquisition system on a monolithic silicon chip. Including a silicon-based sensor, internal voltage reference, and sigma-delta A/D converter, it fits in a 3-pin (power, common, and output) TO-92 transistor package.....
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An electronic speed control for an AC Motor can be
designed with a Light Dimmer IC by limiting the minimum
firing angle of the triac so that the motor wont
stall. This can be done effectively for high volume applications
by making a minor change to the....
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McCAD E.D.S software, a complete family of integrated electronic designs systems for MS Windows and Macintosh OS platforms. McCAD Electronic Design Systems offer a choice of design environments with a wide range of system configurations tailored to the....
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This electronic speed control (ESC) for brushed motors combines the features of two of my earlier designs. One was a high-rate 30A ESC with a brake, and the other a high-rate 12A ESC with a BEC (receiver battery eliminator circuit)...
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This circuit is selective for the tuning adjustment between two closely spaced tones audio. The frequency is dependent on the selective value capacitors and resistors in the feedback circuit between the collector and base of Q1. With the values shown, the....
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Two examples of the most common types of Voltage followers (buffers). You can find some theory behind them in our amplifier gain and buffer amplifier pages.his first circuit is a very simple one transistor voltage follower. Consist of two biasing resistors,....
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This low-cost operational-amplifier circuit (A) generates four different functions with adjustable periods. For the components shown here, the period of the output waveforms is given by T = 4RC and T = 2RC. With switch SI in position A, VI is a triangular....
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This design adopts a well established circuit topology for the power amplifier, using a single-rail supply of about 60V and capacitor-coupling for the speaker(s). The advantages for a guitar amplifier are the very simple circuitry, even for comparatively....
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It is a single stage class A MOSFET design with the right gain and a low output impedance. Here we don't have the limitations of the Zen amps (at least in the single-stage implementations) regarding speaker compatibility. A single stage topology with....
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This preamplifier has a low output impedance, and is designed to drive long cables, allowing you to listen to a remote music source without having to buy expensive screened cables. The very low output impedance of around 16 ohms at 1KHz, makes it possible to....
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This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
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Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723...
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High sensitivity, portable temperature comparator. This sensitive circuit is basically a comparator, detecting very slight temperature changes in respect to the ambient temperature. It was primarily intended to detect draughts around doors and windows that....
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The 040904C version of the code has a larger UART receive buffer and supports two pushbuttons that send either and ASCII "R" ($52) or an ASCII carriage Something to keep in mind when using AVR controllers that support 16 bit addressing(specifically, the....
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The circuit is intended for 117 Vac ± 50 Vac operation, but can be easily modified for higher or lower voltages. It measures true (nonreactive) power beingdeliveredto the load and requires no external power supply. Idling power drain is only 0 W. Load....
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This project has not been called a GOLD! detector as this name has been left for the more complex detectors that actually discriminate been gold and other metals. There is an enormous difference between detecting gold and ordinary metals (called base....
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The circuit in Figure 1 is a quasi-linear regulator. It functions as a source follower for input voltages greater than a preset level, determined by VR3. For input voltages lower than the preset level, the pass element, Q2, operates as a saturated switch.....
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This is a very simple project using a printed circuit board and 8 components. It will flash an ordinary 3mm or 5mm (1/8" or 1/4") LED at a rate of about one flash per second. This circuit works on the basis of a high-gain amplifier being driven into....
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Today`s digital delay lines can process pulses no shorter than their delay times, and that restriction confines the devices to applications in which the duty cycle remains near 50%. A limited range of available delays (2 to 100 nsec per tap) further limits....
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The shift pulse amplitude is less than 15 volts. If a stage is off, the shift pulse will not be coupled to the next stage. If it is on, the diode will conduct triggering the next stage. Just prior to the shift pulse the anode supply is interrupted to turn....
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Portable electronic devices operating from one or more
alkaline or nickel-metal-hydride cells require a boosted
supply that is both small and efficient. Linear Technologys
new LTC®3401 and LTC3402 are high frequency
micropower synchronous boost....
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How would you use an SE with a chip enable? Good question and well one thing leads to another and before you know it a new solar roller is born. The design started out as a simple example of using the 1381wr SE to enable a 74AC240 chip. But with all those....
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This switching circuit acts like a bank of interlocked mechanical switches; pushing one of the buttons latches its corres..
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The temperature sensor provides an input to pin 3 of the NE5037 of 32 mV/°C. This 32 mV is the value of one LSB for the NE5037. The LM334 is a three-terminal temperature sensor and provides a current of 1 p.A for each degree Kelvin. The 32-KO resistor....
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Even if simple the circuit, plirej' all condition, regarding the distortion and the response of frequency. The resistance of entry is 250K and the load that can drive is between 100R and 2K. The circuit use negative coupling. His exit functions in Class A,....
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This transceiver has a 3-stage transmitter and a direct-conversion receiver. Ql is the transmitter"s oscillator, an..
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The pre-distortion circuit described here is extremely simple (Figure 1) and only requires one trimmer adjustment, though you`ll need an accurate way to measure THD in order to achieve the best results. A dedicated distortion analyzer to help you adjust the....
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This circuit uses a FET as a dc amplifier in a bridge circuit. R4 is set for meter null with J1 short circuited. Any surplus 50-mA meter can serve in this circuit. RFC1 is any suitable RF choke for the band in use. A 2.5-mH RF choke will do for broadband....
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Sometimes when experimenting with different soundcards and MIDI interfaces it is useful to see if there is some data going in MIDI interface. This can be easily tested with this adapter, which converts the midi signals to visible light pulses. Just the....
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Why is it that you always test 48 bulbs before you find the bad one in a 50-light string? The simple circuit in Figure 1 allows you to divide and conquer, greatly reducing the time it takes to find the bad bulb. The circuit uses a pair of NE2 neon bulbs with....
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This circuit is designed to detect the presence or absence of aqueous fluids. An ac signal generated on-chip is passed through two probes within the fluid. A detector determines the presence of the fluid by using the probes in a voltage divider circuit and....
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An infrared LED and a phototransistor are used for each eye. Half of a 556 timer IC (ICl-a) functions as an as table multivibrator oscillating at a frequency of about 1 kHz. That IC drives transistor Ql which in turn drives the two infrared LED's, LED1 and....
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This screen uses ten LEDs to display a voltage range of 10.5 to 15 volts. Each LED represents a step 0.5wvolt tension. The heart of the circuit is the 3914 points LM / bar display driver. Trimming potentiometer R5 is adjusted so that 7.5 volts is applied to....
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The dual, voltage-output DACs shown in the figure below employ a combination of power-conserving tricks to draw less than 20µA from a 5V supply. The circuit suits a need for programmable voltage generation in slow or static applications, such as the nulling....