Top Circuits Page 28
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The linear charging ramp is most useful where linear control of voltage is required. Some possible applications are a long period voltage controlled timer, a voltage to pulse width converter, or a linear pulse width modulator. Ql is the current source....
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The circuit uses a CA3060 triple OTA (two units serve as switched current generators controlled by a third amplifier). A CA3160 BiMOS op amp serves as a voltage follower to buffer the 0.0022 µ¥ integrating capacitor. The circuit has an adjustment range of....
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In applications where the period of the input pulses is uneven and the divider is required to cover a wide range of frequencies, the non-integer programmable pulse divider shown can be used. The purpose of the D-type flip-flop (IC2) is to synchronize the....
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The ICM7216A or can be used as a minimum component complete Universal Counter. This circuit can use input frequencies up to 10 MHz at INPUT A and 2 MHz at INPUT B. If the signal at INPUT A has a very low duty cycle it may be necessary to use a 74121....
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The circuit is economical in components, and will work with virtually any transistors and is reliably self-starting. The voltage Vb can be taken from a divider, as shown at the right. If taken from a fixed source, flashing becomes slower as battery voltage....
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The combination of Ql, Q2 and Ul form a hysteresis oscillator to stabilize lamp illumination. In operation, full wave bridge D3 operates directly from the ac line to supply unregulated dc to the lamp and also to the 10 V zener that provides power to the quad....
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Integrated-circuit Ul—an LF351 or 741 op amp—is used as a comparator to control the light. Resistors R2 and R3 provide a reference voltage of about 2.5 volts at pin 3 of Ul. When daylight falls on light-dependent resistor LDR1, its resistance is low:....
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This simple diode modulator delivers excellent results when used for high percentage modulation at low signal levels. Constants are shown for a carrier frequency of about 10 MHz, but, with a suitable tank, the circuit will give good results at any frequency....
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These are modulator circuits for modulation of video signals on a VHF/UHF carrier. The circuits require a 5 V power supply and few external components for the negative modulation mode. For positive modulation an external clamp circuit is required...
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P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils make for much guess work. Tags: 1.....
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Each time a pulse is applied to the conversion of the control input, Ql resets the 1000 pF capacitor to 0 V. This action takes 200 ns to reset the falling edge of the convert command pulse, the capacitor begins to charge linearly. In exactly 10 microseconds,....
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I used the original board layout shown in the magazine article as well as the original driver transistors. However, due to the unavailability of the original power transistors, I opted for a more robust output stage using Toshiba 2SA1943 and 2SC5200....
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The difference between these amplified signals is used to set the 's bias and hence Ql Q2 current channel. This Ql forces of V GS at all that is required voltage corresponding to the circuit input and potential output. The capacitor of 2000 pF to Al provides....
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The control circuit operates to double from a positive supply, which, when turned on the power of the first door. and goes off when the first drain as shown in FIG. This circuit integrates the LM123, a three-terminal positive regulator and a dc dc +....
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Most amps acoustic frequencies that make our readers, instead of a transformer power, sometimes required two or sometimes three. This tactic is more common in amplifiers 'High-End', where the altar of high fidelity are all eager to sacrifice their economies.....
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The circuit is so simple that there is little to say about it, but it gives very good results. Tr1 is operated in grounded base mode with input to its emitter to give low impedance input. The values shown give correct operation from 9v. If operating from....
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This preamp is very simple, and will work under tough conditions. The input impedance is pretty high, so it won`t load down electric guitars. It will also amplify microphones. When I have a moment, I`ll make some additions that will optimize it for....
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If two of these circuits are made in the same enclosure for stereo, then there can be a single power supply to run both of them. There should be a resistor in series with the incoming 9V+ lead so as to minimize crosstalk, and reduce the PLOP when it's....
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A simple circuit for evaluating the performance of the fi lter. The LTC1560-1 offers a pinselectable cutoff frequency of either 500kHz or 1MHz. The fi lter gain response is shown in Figure 2. In the 1MHz mode, the passband gain is fl at up to (0.55)(fC) with....
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This is an image Schematic. No Description available...
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This circuit will be of interest to the radio amateur and anyone posessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the....
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This amplifier has about 20dB of gain, bandwidth of 100MHz and noise figure of about 7dB. The output transformer is 8 turns bifilar wound on a ferrite core. Use a medium power UHF transistor 2N5109, 2N3866, 2N4427 or similar. The transistor will need a small....
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The car alarm here is a simple circuit with basic characteristics that cover all entrances at the car that has switches (doors etc).With one switch (arm-switch) the circuit waits for the sensor-switches to open and to activate it. So the horn with 1 sec....
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The IRISMPS5 is an open frame 90W Flyback power supply unit (psu) using the IRIS4015 Integrated switcher. This demo board aims to show the capability of the IRIS4015 to handle the upper level of flyback topology power range, without the strict standby power....
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A basic full wave rectified power supply is shown below. The transformer is chosen according to the desired load. For example, if the load requires 12V at 1amp current, then a 12V, 1 amp rated transformer would do. However, when designing power supplies or....
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Rectifier circuits based on semiconductor diodes typically handle voltage levels that greatly exceed the diodes` forward-voltage drops, which generally don`t affect the accuracy of the rectification process. However, the rectified signal`s accuracy suffers....
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A high voltage step-up DC power supply using adjustable flyback conversion...
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I have received a few emails asking for a transformerless power supply. Here is such a supply. This supply uses no heavy step down transformer and has an extremely low parts count. The circuit can be built very small and can supply small currents for small....
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The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current....
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National Semiconductor's DP8464B is primarily intended for use in disk systems as a pulse detector. However it can be easily used as a general purpose peak detector for analogue signals up to 5 MHz. The chip can handle signals between 20 and 66 mV....
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The figure shows two TL3103 linear Hall-effect devices used for detecting the angle of rotation. The TL3103s are centered in the gap of a U-shaped permanent magnet. The angle that the south pole makes with the chip face of unit #1 is defined as angle 0.....
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A flip of 51 puts the system in action. Power for the circuit is captured from the ignition switch, and circuit receives no power until the ignition switch is closed. When the camera is turned on, the capacitor C1 is charged and the emitter follower....
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The LT®1180 RS232 transceiver includes a charge pump which produces low ripple supplies with suffi - cient surplus current to drive a CMOS A to D converter and precision voltage reference. The circuit in Figure 1 operates from a single 5V supply, and draws a....
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The XR-T6425 Speakerphone IC makes it possible to carry on conversation without using the handset, while the user is talking into a microphone and listening from a loudspeaker. It is ideal for hands-free conference calls. ..
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The XR-T5995 Speech Network is a monolithic integrated circuit specifically designed for implementing a low cost telephone circuit.
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It's a simple metal detector design that has the quite good characteristics. the principle of operation which one differs from the classic schemes (BFO, transmit-receive known as "two-boxes" metal detector, inductive). The dynamic mode is used to find....
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This simple metal detector requires only a handful of components and an evening's work. Built around a cmos4011 IC, is very robust and versatile. The 250 kHz reference oscillator is built with two gates (U1/1 and U1/2), C1, R1 and P1. The search oscillator....
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The circuit uses two CMOS IC’s
IC1 uses inverters connected as a Colpitts oscillator of 100KHz; the LC frequency determining elements being the search coil and parallel resonating capacitor.
An 80 turn close wound 30swg 100mm diameter coil will fit inside....
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The circuit provides illumination when darkness comes. By using the gain available in darlington transistors, this circuit is simplified to use just a photodarlington sensor, a darlington amplifier, and three resistors. ..
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Feedback control of the phototransistor in this optical detector helps negate the effects of varying ambient light sources. The output of a modulated visible-light LED is detected, amplified, buffered, and fed through a low-pass filter.
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Designers who build equipment for the industrial market share a widespread problem. At one extreme, they must build equipment that supports ±10V bipolar voltages, often riding on a high common-mode level, a requirement enforced by 30 years of legacy....
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The computer needs at least 180 millivolts peak-to-peak and the condenser microphone in my headset produces about 20 millivolts peak-to-peak into a 2.2k load with normal speech levels. There are USB ports on the machines, so I can use that for +5 volts.....
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The photodiode specified responds linearly to light intensity over a 100 dB range. Digitizing the diodes linearly amplified output would require an A-D converter with 17 bits of range. This requirement can be eliminated by logarithmically compressing the....
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This is a simple Laser communication system. It can transmit and receive signal from any audio device.Communication distance is few meters. All components are not critical. Transistor 2N2222 may be on the coolrib. Laser diode is from laser pointer...
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The completed board may be driven by voltages between .8 and 3 Volts. While the basic design goal was candle like light from a single cell, the values used were chosen to allow safe operation from 3 Volts so you can, for example, use it to drain the last bit....
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This may be the simplest LED flasher circuit you can build, with the notable exclusion of LED's with integrated flashing circuits. This might be a good replacement for the LM3909 in some applications. Take a close look. Only the emitter and collector leads....
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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 circuit is powered by a single 1.35 V mercury cell and provides a 1 V square-wave output. As shown, the crystal is a tuned circuit between transistors Ql and Q2, which are connected in the common-emitter configuration. Positive feedback provided by means....
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A frequency reference for tuning up the RS-232 to 100 MHz RF desktop channel adapter elsewhere on this site, when I found this Saronix crystal oscillator in my junk box. A few minutes with AVRStudio produced an ATtiny12 to make a tone - even fewer parts....
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This circuit responds to RF signals from below the standard broadcast band to well over 500 MHz, and provides a visual and audible indication when a signal is received. The circuit is designed to receive low-powered signals as well as strong sources of....
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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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The circuit has been designed to accommodate all those who dedicate many hours of their lives by exploring the endless pages of this site. Despite the fact that it consists of only three components (Most were not little!), Is able to provide an indication of....
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The voltage reference circuit described below, is a special implementation of current source LM334. Characterized by a very small temperature coefficient metatholio output voltage and consumes only 10uA room temperature. This current fluctuates by a few uA,....
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The circuit is a light switch who triggers when light drops on photo resistor. It is fairly simple in construction and can be used in a million applications. The photoresistor and the trimmer work as a voltage divider and also polarize the transistor TR1.....
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Capacitor Cl is charged to +28 V through Rl and stores energy for firing the squib. A positive pulse of 1 mA applied to the gate of SCR1 will cause it to conduct, discharging Cl into the squib load XI. With the load in the cathode circuit, the cathode rises....
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A power transistor can be used to provide a high powered zener voltage from a low wattage zener. A 400 mW zener can be used where a 10 watt zener is required or a 1 W zener can be used where a 50 to 80 watt zener is required by using appropriate transistors....
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The heart of the lock is the 40022 octal counter. When first powered C2 is charged via R5 so the reset input of the counter is kept high. That causes output Q to go high while all the other outputs are low. With the switches wired as shown, when S4 is....
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The circuit uses a Signetics NE565 PLL (Phase-Locked Loop) as a detector to recover the SCA signal. The input to the SCA decoder circuit is connected to an FM receiver at a point between the FM discriminator and the de-emphasis filter network. The PLL, IC1,....
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This is a small but quite powerful FM transmitter having three RF stages incorporating an audio preamplifier for better modulation. t has an output power of 4 Watts and works off 12-18 VDC which makes it easily portable. It is the ideal project for the....
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A composite stereo signal, as transmitted by FM radio stations, is composed of at least three parts: A base band mono signal, a double sideband channel difference signal, and a pilot carrier. The signal composition is somewhat analogous to an NTSC composite....
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This implementation is adapted to rebroadcast the output of a CD player, television receiver, or radio receiver. I use it so that I can move about the house and listen to my favorite programs without disturbing others. Within and the house, I find that I can....
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The circuit is based on an LM3914N bar graph display driver device (IC1), which can be used to drive up to ten LEDs. This is connected so that with OV12 at the input only the first LED indicator switches on. This simple peak reading VU meter circuit uses six....
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Diode Dl prevents negative spikes from occurring at the MOSFET gate, the 100 ohm resistor is a parasitic suppressor, and Z1 serves as a dissipative voltage regulator for the output and also clips the drain voltage to a level below the rated power FET....
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The 2N4416 JFET will provide noise figures of less than 3 dB and power gain of greater than 20 dB. The JFET's outstanding low crossmodulation and low intermodulation distortion provides an ideal characteristic for an input stage. The output feeds into an....
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On those occasions when we want to see if an amp works, the best tool we can use is a source of acoustic signal with a frequency around the 1 kHz. These characteristics can be merely 'tolerated', because in cases of rapid tests rarely consider whether the....
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A dual optocoupler is used in a configuration which has the same current throughout as the LEDs. Assuming similar optocoupler features the output voltage must be equal to the non-inverting input voltage. Since the op amp is within a closed loop the output....
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An inexpensive electronic thermometer is capable of measuring temperatures over a range of from -30°F to +120°F. A diode-connected 2N3904 transistor used as the temperature sensor forms a voltage divider with Rl. As temperature increases, the voltage drop....
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"Should I cut the blue wire... or the red...?" This is a very common phrase in many movies when the action hero has a bomb in front of him with little time left and he has to choose which wire to cut and stop the bomb from exploding saving millions of....
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This circuit is able to take you to the world of the Wild West. For this it uses the integrated 18-pin IT82207 (IC1) of Holtek, which literally takes care of everything. You have to do is add a few accessories, including a loudspeaker and six selector....
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Transformer Tl can be any matching transistor type in the range of 500/500 to 2500/2500 ohms. No connections from the SCR or its components are connected to ground. For safety's sake, keep the 117-V line voltage from the amplifier connections— that is the....
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The circuit is completely conventional, and has been around almost forever in one guise or another. Similar circuits were used in the valve (tube) era, so there is nothing new about it. The circuit has already been published on these pages as a guitar....
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The automatic fader drops at the background music while the narration is in place. The control input through RIO, a preset audio level control, into an emitter-follower buffer stage CQI). The buffer provides high input impedance and ensures that the source....
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The microprocessor sends out an 8-bit binary code on its 8-bit I/O bus (the binary value needed to program the ICM7240), followed by four WRITE pulses into the CD4017B decade counter. The first pulse resets the 8-bit latch, the second strobes the binary....
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The circuit is based on the type EL2020 (or similar) operational amplifier which is marled by large bandwidth. The LL2020 amplifies the video signal applied to the input stage, with a gain adjustment range of ±6 dB. Output transistor Q1, a 2N3866, applies....
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The popular USB interface can charge a portable device while transferring data. But for high-capacity batteries, the 500-mA output current of USB hosts and powered hubs greatly extends the charging time. (Unpowered USB hubs supply no more than 100 mA.) Thus,....
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so what happens when you flip a switch? When you try to stop the flow of current in 'zero' time its equivalent to trying to stop a freight train instantaneously. you get a huge voltage buildup "dv/dt" = "X/0=infinity This is one example of the use of a....
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It's very simple actually. The idea is that we use what we have learned from the capacitor tests to create a circuit that uses the capacitors to run the load and then by discharging the 1/2 full capacitor into a DC-DC converter we can recharge the initial....
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This is a silicon transistor circuit showing typical voltage values. When the forward base/emitter voltage is 0.6 to 0.7 V, the transistor is silicon. Germanium transistors will have a forward base/emitter bias voltage of 0.2 to 0.3 V This is a silicon....
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The circuit consist of 10 k and 470 k resistors. Also one potentiometer resistor and led was used. This circuit is used for learning Arduino programming later in class...
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This is the low cost AVR programmer using attiny2313. The schematic diagram is given below.
First setup the circuit as shown. One important care taken to make fuse bit
avrdude -c usbasp -p t2313 -U hfuse:w:0xdf:m -U lfuse:w:0xef:m
If you use serial port....
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This metal detector schematic circuit is based on a transistor radio as an detector .This metal detector is total different that other metal detectors, because this circuit doesn't have a speaker . With the radio tuned to a weak station you must adjust the....
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This system performs a complete conversion of 12 bits in 10 p unipolar or bipolar. This converter is accurate to ± 12-bit LSB Y2 and a typical gain TC of 10 ppm / ° C. In unipolar mode, the system range is 0 V to 9.9976 V, with each bit having a value of....
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Can be directly connected to CD players, tuners and tape recorders...
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Another very simple audio preamp to build. all parts should be available at your very local electronics shop...
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This circuit mixer has an internal amplification with 2N3563 transistor. The two input signals can be independently controlled by VRI and VR2. The VR3 balance control is used to remove a signal while the other melted. ..
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This is an image Schematic. No Description available...
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With graphic equalizer we make selective cutting off or boost, of selected departments of acoustic spectrum. With this way we can adapt the musical reproduction, in the characteristics of space where we hear. This can create however also problems if go to....
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A classic circuit of regulation of tone of three way, with which we can regulate low, mid and high frequencies, of acoustic signal. The boost/cut can be regulated in the range of ± 18 dB/oct. In the circuit the supply is ± 15V, but can be also supplied with....
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The EQ-2 it is a circuit of graphic equalizer 6 band of regulation. Each band is regulated from the potesometers RV1-6, that are, for better optical indicate of regulations, Fader. This does not mean that we cannot him replace with simply potesometer. In the....
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The AM signal is captured by the antenna , 10 mt long horizontal wire, WELL insulated from earth (I mean distant, to lower the stray capacitance coupling with ground which will adsorb some signal ). The Inductor and capacitor forms a resonator, that will....
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In the "Trace" mode the non-linear operation of the amplifier will detect modulated rf signals which will be filtered by the .001 µ¥ capacitor and heard in the headphones.
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The MC74HC04 IC is a low cost CMOS Hex Inverter. I used this type mainly because, it is what I have, although you can use LS type but, with a little modification or exemptions....
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When this car alarm circuit is activated it stays activated for 80 seconds. It has 15 seconds delay for the driver to enter and deactivate. and All timmings can be altered easilly.....
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The power supply section is the important one. It should deliver constant output regulated power supply for successful working of the project. A 0-12V/500 mA transformer is used for this purpose. The primary of this transformer is connected in to main supply....
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Is it possible to use DRAM with microcontroller AVR? Yes, it is possible. Jesperh has proved it. He hooked up a DRAM to a small processor (in this case an Microcontroller Atmel 8515), and handle the RAS/CAS sequencing and refresh in software. The type of....
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model airplanes, boats, cars and use of ignition of glow plugs for their miniature (O. Bcc to 15cc) internal combustion engines. These engines happen with the heavy batteries on board, HT coil, and "condenser" spark required for ignition classic, while....
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If you are searching for the 8255 datasheet, click here. Another project describing the 8255 interface to PC is here...
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Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere. It detects RF via a square law detector, basically its a crystal set with....
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IC-1 and the associated circuitry form a stable audio tone generator that feeds a buffer amplifier, Ql and Q2. The tone output is taken from the emitters of the transistor pair to supply a carrier voltage for a balanced modulator made up of four diodes—Dl....
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The working principle of this cheap and easy to build metal detector circuit consists in mixing two equal frequencies which causes a low-frequency interference. When one of the oscillators become unstable then the frenquency of the interference will be....