New Circuits Page 205
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This de adapter provides a regulated 9-V source for operating a Kenwood TR-2500 hand-held transceiver in the car. The LM317T"s mounting tab is electrically connected to its output pin, so take this into account as you construct your version of the adapter. ..
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This really isn't much an electronics project as it is a telephone wiring project. Take note that this proejct involves connections to telephone lines. This may be frowned upon by your telephone service provider, AKA The Telephone Company. Always use proper....
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We have developed a powerful yet inexpensive and easy to construct experiment control system. The construction of the system together with the control software is described here. All circuits and software are free to download and use for nonprofit. The....
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It provides much quicker turn-on when the Sun goes down. Note that a smaller value for the resistor will provide faster turn-on; the trade-off is that a smaller value for the resistor also makes the solar engine less efficient at charging the capacitor....
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Most circuits that provide an electrical stimulus for research subjects are constant-voltage designs; this circuit is a constant-current design. Stimulator circuits must be isolated for two reasons: to ensure safety and to minimize interference. Isolated....
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The modified power-factor controller, developed at the Marshall Space Flight Center, employs a phase detector for each of the three phase windings of a delta-connected induction motor. The phase-difference sum is the basis for control.
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A bar graph driver IC LM314 drives anXED display. The LEDs may be separate or in a combined (integral) bar graph display. Calibration: With a precision meter be-tvveen pins 4 and 6 adjust Rl for voltage Vq of 1 20V. Apply 4.94V to pin 5, and adjust R4 until....
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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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Circuit uses an astable multivibrator to vary the heads-or-tails condition, and a flip-flop to store the condition given by the multivibrator..
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Up to 100 lights, LEDs, or optocoupler triac circuits can be sequentially activated by this circuit. One (Ul) 4017 decode co..
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SW1 bypasses the crossfeed network. I have reconfigured the original crossfeed schematic so that now the 100k resistor always bridges the bypass switch and thereby reduces any 'crackle' or 'click' or whatever you may call them. Don't omit these 100K....
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Three-amplifier circuit consumes only 135 /tW of power from a ±1 V power supply. With a gain of 101, the instrumentation amplifier is ideal in sensor interface and biomedical preamplifier applications..
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Sorry, I don`t have any data/instructions for use on this schematic. If anyone knows how this circuit works or is used, please drop me an email at click here or use the feedback form...
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This document describes the transmitter system supplied to Radio Glen for testing as designed and constructed by Henry.
The transmitter is supplied in prototype form and has the physical limitations of an instrument constructed using prototyping....
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This is my own version of the classic PIC 16C84/16F84 programmer. The design is originally by David Tait. I`ve made a few changes, redrawn the schematic and done a board layout. All the files you will need are linked below, including software you`ll need to....
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ICla and IClb are wired as a slow astable multivibrator and IClc-ICld are wired as a fast astable. The output of the slow astable modulates the frequency of the fast astable, and the output of the fast astable is fed to the external speaker via the Ql VMOS....
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The unknown resistance is put in series with a known standard and a current passed through the pair. The voltage developed across the unknown is applied to the input and the voltage across the known resistor applied to the reference input..
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In many µC applications, a signal conditioner modifies an analog input signal from a sensor and passes it to the µC for processing. The last stage of the signal conditioner is always a device that transforms the signal level to a value acceptable for the....
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A sensitive radiation monitor may be simply constructed with a large-area photodiode and a quad operational amplifier. Replacing the glass window of the diode with Mylar foil will shield it from light and infrared energy, enabling it to respond to such....
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Glitch has been a universal slang expression among electronics people for an unwanted transient condition. In D/A converters, th..
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The device comprises two parts: LED control board and LED display board. The two PCBs are designed to fit together one behind the other using two sets of dual row connectors and 4 spacers. One of this connector is used for the electrical connections, while....
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This peak detector uses a CA3100 BiMOS op amp as a wide-band noninverting amplifier to provide essentially constant gain for a wide range of input frequencies. The IN914 clips the negative half of VfN (R4)/(R3) (R5). ..
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Put the car in reverse and the circuit provides a loud, audible beep at the rate of about one per second (1Hz). Half of U1, a 556 dual oscillator/timer, is used as a slow-pulse oscillator with a rate of about 1Hz. Components R2, R1, and C1 form the long time....
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The regulator delivers 100-V at 100 mA and withstands shorts to ground. Even at 100 V output, the LT317A functions in the normal mode, maintaining 1.2 V between its output and adjustment pin. Under these conditions, the 30-V zener is off and Ql conducts.....
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This is a ring-modulator which doubles as a tremolo. It was designed as a replacement for the somewhat over-complicated ElectroHarmonix Frequency Analyzer with its ridiculous high-voltage wall-wort and huge metal box. I've got it down to a 3080 OTA and a....
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The power supply uses two VN4000A 400-V MOSPOWER FETs in a half-bridge power switch configuration. Outputs available are + 5 Vat 20 A and ±15 V (or ±12 V) at 1 A. Since linear three-terminal regulators are used for the low-current outputs, either ±12 V....
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Three lights are controlled by the three channels. One light will pulse in response to the bass, another illuminates with mid-range sounds, and the last lights for high notes. Four level controls allow adjustment of overall light level and each channel....
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This circuit detects the presence of audio (voice) on the output of a scanner. If the scanner stops on a "dead carrie..
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This DC-to-AC inverter schematic produces an AC output at line frequency and voltage. The 555 is configured as a low-frequency oscillator, tunable over the frequency range of 50 to 60 Hz by Frequency potentiometer R4.
The 555 feeds its output (amplified by....
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I ride my bike allot at night and sometimes I'm not sure if people can see me. This circuit will flash an incandescent light that you can purchase from Radio Shack. Adjust the VR's for your flash requirements and make sure that the lamp you use is designed....
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Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need.
A correct grounding is very important to eliminate hum and ground....
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To provide good signal-to-noise ratio, this four channel mixer amplifier controls the signal levels after the amplifiers, and then mixes them to offer a combined output. The circuit works with any 50 ohm to 50 K dynamic microphone but not with crystal or....
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Here is a very simple, inexpensive and interesting project which provides lot of fun to a home experimenter or hobbyist. This simple transmitter can transmit speeches or songs within a short range. The circuit uses only one transistor. The entire circuit can....
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This locater is made up of two parts. The first is an rf oscillator, whose circuit is shown in Fig. 8-4a. The second is a sensitive receiver shown in Fig. 8-4b. The heart of the oscillator is a 555 timer !C. Tank circuit C2 and L1 is used to tune the....
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To maintain content in the event of power loss, many designs that include SRAM require a dedicated device that can automatically switch from a standard power supply to battery operation. Microcontrollers seldom find use in power-switching applications.....
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Data acquisition is the process by which events in the real world are sampled and translated into machine-readable signals. Data acquisition typically involves sensors, transmitters and other instruments to collect signals, waveforms etc. to be processed and....
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The heart of the electroscope is the two junction FETs Ql and Q2 connected in a balanced-bridge circuit. The gate input of Ql is connected to the wire pick-up antenna, while Q2"s gate is tied to the circuit"s common ground through R2. That type of bridge....
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This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc.
This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC.....
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The Generator cell must have reasonable surface area on the Plates to generate a reasonable amount of Hydrogen/Oxygen. And a Typical construction would use Stainless Steel for the Electrodes to prevent them from being Quickly eaten away...
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Conventional monolithic micropower op amps with a
wide supply voltage range require a large die area and
therefore, a large package and footprint. The unconventional
LT®6011 dual op amp fits 25mV input precision
micropower operation and wide 2.7V to 36V....
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The most important criteria of a data-acquisition system for college science laboratories are simplicity and price rather than precision or speed. The data-acquisition system in Figure 1 offers adequate precision of less than 0.5% and speed of 1 Hz to....
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This circuit detects low-voltage supply conditions, down to 0.6 V. Dl sets the trip point of the cir..
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The timer is proposed an effective model for controlling an external load 8A/380V. Equipped with a 68HC11 mu.P associated with an 8 MHz crystal, it can get very precise programmable durations. Two lines are planned: from 0 to 99 seconds and from 0 to 99....
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This simple circuit consists of only two timing components Rr and Cr, the NE555, and bypass capacitor C2. While not essentiaHor operation, C2 is recommended for noise immunity. During standby, the trigger input terminal is held higher than 1/3 Vee and the....
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An LM311 comparator converts a small analog signal to a digital level for the DC4046 phase-locked loop, which is configured as a first-order FM demodulator. This demodulator works with a 50-kHz FM modulated input signal. It has applications in FM light beam....
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This device is a stereo amplifier for a high sensitivity stereo parabolic microphone. It can be used for listening to distant sounds. The Big-E can be used with headphones or as an audio source for a stereo tape recorder or a PC sound card. This circuit also....
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The NanoVM is a java virtual machine for the Atmel AVR ATmega8 CPU, the member of the AVR CPU family used e.g. in the DLR Asuro robot, manufactured by AREXX engineering. With the NanoVM, the Asuro can be programmed in the popular Java language using the....
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All dedicated current-sense amplifiers provide high-side sensing on a positive supply, but you can adapt such circuits for monitoring a negative supply (Figure 1). The positive-supply pin, V+, connects to the system`s positive supply, and the ground pin,....
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Probably the best advantage is its very small size and the fact that it can run off the power supply of the circuit being tested. Although it has a low frequency range, it can still be used for most circuits. Its poor resolution will still allow for most....
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I have used this type of circuits for quick testing of telephone equipment. This is a quick hack that does not exactly resemble the characteristics of the real telephone network, but is enough for this kind if applications. If you want better simulation,....
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Using an oscillator running at 455 kHz, the metal-detector circuit produces an indication on the meter Ml. When the oscillat..
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ICl and IC2 form an inverting half-wave precision-rectifier/peak-detector circuit. Negative input-signal, swings with peaks larger than the voltage on Cl, cause this capacitor to charge to the new peak voltage. The capacitor holds this voltage until a....
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We hold the "first rights" to the presentation of this approach and the best part is: "It's FREE!"
The PIC12C508A is one of the most amazing devices but because it does not come in a low-cost re-programmable form, it has never been presented in a....
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The output frequency of the VCO, U1, varies inversely with the input voltage. With a 1 "V input, the oscillator output frequency is about 1500 Hz; with a 5-V input, the output frequency drops to around 300 Hz. The output frequency range of U1 can be....
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At a predetermined level of declining terminal voltage, the circuit disconnects the battery from the load ..
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This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a....
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This circuit is ideal for use as an over-under temperature monitor, where its dual output feature can be used to drive HIGH and LOW temperature-indicator lamps, relays, etc. Tl is a 6.3 volt filament transformer whose secondary winding is connected inside a....
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The circuit consists of four stages of active bandpass filtering provided by two type-µ integrated-circuit dual op amps and includes a simple threshold detector (diodes Dl and D2) between stages 2 and 3 to reduce low-level background noise. Each of the four....
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In intrinsically safe applications, it is sometimes necessary to separate sections of circuitry by resistors which limit current under fault conditions. The circuit shown provides an accurate analogue output with effectively zero output impedance, despite....
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The frequency doubler uses only one !C. Like other doublers, this circuit uses both the rising and falling edges of the input signals to produce digital pulses, thus effectively doubling the input"s frequency. Without the rc networks at IC1 inputs, IC1....
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Electrolytic capacitors are unnecessary to generate a 1 cps frequency. As an scs triggers on, the 0.2 µ¥ commutating capacitor turns off the other one and charges its gate capacitor to a negative potential. The gate capacitor charges towards 24 volts....
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The amp is rated at 100W into a 4 Ohms load, as this is typical of a "combo" type amp with two 8 Ohm speakers in parallel. Alternatively, you can run the amp into a "quad" box (4 x 8 Ohm speakers in series parallel - see Figure 5 in Project 27b, the original....
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This simple stereo amplifier uses a National LM3871C. The pin numbers in parentheses are for one channel, and those not in parentheses are for the other channel. The supply voltage can be +9 to +30 Vdc at about 10 mA. The output voltage swing is about....
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This is an image Schematic. No Description available...
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When power is applied to the circuit, the heater coil in the sensor is energized by the 5-V output of IC5, a 7805 voltage regulator. Breathing into the sensor with alcohol on your breath will lower the sensor"s resistance; consequently, the input voltage....
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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 neat little circuit provides 8 LEDs directly driven from the PIC along with a single mode control switch. The firmware elsewhere on this page drives the LEDs with a 5 bit PWM signal providing each of the 8 LED channels with four levels of intensity;....
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The 2N5457 and PN2222 bipolar serve as voltage isolation devices between the output and the current sensing resistor, Rl. The LM101 provides a large amount of loop gain to assure that the circuit acts as a current source..
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This project is an High precision digital thermometer which indicates the temperature on the seven segment display. It has an resolution of 0.06deg.
The 1 wire temperature sensor IC from Maxim semiconductors is used as the sensor. The DS18S20 Digital....
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This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 2 24LC32 eeprom memories is being used, the 1st for internal standard melodies and the 2nd one is for user's compositions. This feature will be provided....
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This simple circuit can detect the invisible fields of voltage which surround all electrified objects. It acts as an electronic "electroscope." Regular foil-leaf electroscopes deal with electrostatic potentials in the range of many hundreds or thousands of....
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This incredibly simple thermometer plugs on any free serial port. Does not make use of any programmable components as microcontrollers. It gives temperature readings accurate to 0.5°C with no calibration. It's cheap, so I've put one on any PC I use. And it....
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This circuit uses a set of 13 differently colored LEDs to generate a full color spectrum. The photo does not fully represent the colors generated due to camera limitations. The real-world display is very eye-catching. If you want to "trick out" your PC, this....
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This Design Idea outlines an easy-to-implement time-delay routine that requires no subroutine calls and thus avoids possible stack-overflow problems (Listing 1). This method also saves RAM space by requiring in most cases only two variables: the PACER_CLOCK....
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Is a 100 to 200 metre (100 to 200yds) device having a very stable performance. It can be used as a hand held microphone or left on a shelf to pick up the sounds in a room.
It has many interesting features. These will be fully described in the article. One....
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This page shows some methods of track routing control for Stall-Motor type switch machines. The principle method uses a 2 Pole - Multi Position rotary switch while an alternate uses optoisolators and transistors to select the routes. The last circuits on....
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Here's an effective little combination lock that you can put together in one evening's time. To open the lock, simply dial in the correct combination on the three rotary or thumbwheel switches. With the correct combination entered, current flows through Rl....
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This circuit uses a UM3561 IC to produce four different sound effects. Nothing too complicated here. The IC produces all the sound effects, the output at Pin 3 being amplified by the transistor. A 64 ohm loudspeaker can be substituted in place of the 56 ohm....
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The i2c-tiny-usb project is an open source/open hardware project. The goal of i2c-tiny-usb is to provide a cheap generic i2c interface to be attached to the usb. It is meant as a replacement for those simple and cheap printer port to i2c adapters. A USB....
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The circuit in Figure 1 controls 32 voltage-output channels from the parallel port of a PC. The circuit comprises eight DAC7615 quad voltage-output, serial-data programmable, 12-bit DACs. The controlling PC individually programs each of the 32 DAC channels,....
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The schematic has been modified slightly to improve the tone control performance (04 Jan 2002). A new schematic is now on line - the differences are relatively minor, but make the component values for the tone controls a bit cheaper (smaller value caps, and....
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The achievement of this 30 watt amp was thought to take place on a heatsink microprocessor PC. Equipped with its fans, the advantage of this method of cooling was chosen for the fact it is common and not very expensive. The size of the printed circuit will....
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The voltage regulator is an LM317T, and should accept up to about 14 volts without problems. It can handle up to 1 amp, but you WILL need a heatsink on the voltage regulator. I also added DC power jacks for input and output on my voltage regulator, a green....
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This circuit inverts the polarity of the input. output is limited to less that 200mA...
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All resistors are 1/4W.The circuit is powered by 9...15V DC or AC. When In Circuit Programming (ISP) connectors are used, is possible the programmer to be powered from target?s power source. Diodes D2 and D6 protect the regulator LM7805, when target?s power....
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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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This site contains public-domain schematics for a dual-trace, triggered oscilloscope, and some theory. Click on the topic in the table below to see the schematic for that block. I designed and built this oscilloscope in 1986 using the chassis of a....
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The analog switch multiplexes between channel 1 and channel 2 at the end of each sweep. Controls include Dual Trace/Single Trace mode, sync polarity, sync level, and sync on + or - (rise or falling) edges...
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The cireiilt is built around a couple of low-cost ICs: an H11C4 optoisolator/coupler with an SCR output (Ul) and an LM3909 LED flasher (U2). It is connected to the phone line in the same manner as any extension phone. A ring signal on the telephone....
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No Description available...
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The design philosophy for this circuit was centered on replacing all of the op-amp circuitry found in the earlier circuits with discrete transistors and LC filters. The previous circuits had many (high quality) op-amps in series, this resulted in audible....
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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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I designed this circuit. It can be connected to an FM tuner to play FM stations on an AM radio...
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Spring reverb units are most commonly used in guitar amps, having been replaced by digital effects in most other areas. This cannot really be classed as a "real" project, because the circuitry is somewhat experimental, and may change quite dramatically....
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LM13700 VCAs are used in a configuration identical to that shown in the Nat Semi data sheet that produces minimal distortion. It is not perfect but then VCAs never are. Two VCAs are used in inverse polarity for each of the X and Y multiplier sections to....
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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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The Class A series resonant inverter portrayed is well-known and respected for its high efficiency, low cost, and small size, provided that operating frequency is greater than about 3 kHz. ..
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The Videowire converts a baseband video signal into a low impedance differential signal that can
be sent over ordinary four conductor telephone wire. A send board mounted close to the camera
generates the differential signal and a receive board near the....
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That RF Amplifier is for boosting small fm transmitters and bugs. It use two Philips 2N4427 and its power is about 1Watt. At the output you can drive any linear with BGY133 or BLY87 and so on. Its power supply has to give 500mA current at 12 Volts. More....
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Afterwards the Modular preamplifier presentation good is I present also a simpler circuit in the manufacture but very good quality. And in this circuit the philosophy that follow is: simple is also better. As you will see in the circuit, it was used only....