Top Circuits Page 231
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A Miniature Real-time Controller controls night light, A/C, household appliances with programmable scheduler. Modified source code and hex file for year 2002 readout. This is my long history the device that controls my home`s night light, air-conditioner,....
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A Microchip PIC12C508 8-pin CMOS Microcontroller turns a night light on and off with preset time everyday. Save Energy, No EMI, No Battery, Built-in Lamp Fixture, and Peak Shaving It`s time for 8-pin microcontroller Microchip PIC12C508, the SAVER V3. 2, my....
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The Saver V5. 0 runs simple clock emulation program, turns a night light on and off with preset time, say 19:00 to 22:00 everyday. The design features low cost, easy installation, no battery backup and no EMI. The AT89C2051 uses external oscillator generated....
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The complete hardware schematic of the Night Light Saver V6. 0. The AC line was protected F1, a 1A fuse. Any short circuit caused by saver`s components will blow the fuse. R1 and C1 limit current to the +5V zener diode, D3. R2 discharges capacitor C1 when....
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This is my student assignment for the class "Designing Microprocessor Based Instrumentation". The board demonstrates the use of 12-bit ADC, writing c program with digital filtering and interface the LED display. The reading provides 0. 1C sensitivity. The....
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The enable signal for USB chip and GLCD controller were made by PLD decoder from the address lines. As we have seen the memory map for i/o of 8051SBC board, the available space is from 0x0300-0x07FF. The address range of 0x0300-0x03FF was used for USB chip....
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The Hartley Oscillator is an L C oscillator that derives its feedback from magnetically coupled energy in a tapped coil. Hartley oscillator are inductively coupled variable frequency oscillators...
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Figure shows the V-I curve for a typical solar panel (Sharp ND-224U1F), and output power under different lighting conditions. The solar panel behaves like a constant current source at high current, and like a voltage source at low current. The transition....
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The circuit is only suitable for fundamental crystals as there are no mode suppression components. The oscillator transistor Q104 is cutoff most of the time except for a short period at the peak of the crystal current waveform. Q103 regulates the dc....
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J1 And J2 are a matched pair of J310`s (can also use U310`s or a U431 matched pair). R2 is selected to bias the 2 FETs with a small drain current with no RF input. The turns ratio of the input transformer is selected for an approximate 50 ohm impedance match....
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This page contains material related to the technical issues on taking meteor counts thus monitoring the meteor influx using VHF radio receivers. It is not meant to be a comprehensive how-to guide, but tries to fill some gaps and give second opinions on....
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Older TV sets that do not have a diode split flyback usually contain a flyback that gives about 8kV peak, and a subsequent cascade which triples this to about 24kV. These cascades are moulded modules with a number of wires or solder points for input and....
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If the unit has been sitting idle for a long period time (dead AAA batteries) and you see only garbage on the display or the unit doesn`t operate, the first item required is probably a new internal lithium battery. Although the unit was exceptional for its....
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Ever since I built a MythTV, I have been able to eliminate my DVD and VCR remote controls. However, I still needed my television remote control to turn on the TV as well as to control the volume, mute, and video input signal selection. For a while, I didn`t....
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I have managed to let the stock ATS-3A transceiver transmit nice BPSK31 "cq ok1iak". The firmware of ATS-3A was modified to allow serial line control, which is performed over the DASH paddle pin in straight key mode. That means paddle will not work if in....
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Many of us who invested in Prologic decoders are now looking at Dolby Digital. New formats like DSS, DVD-Video and High Definition Television incorporate this new technology; but what about the old laserdisc format After all, more than 600 laserdiscs feature....
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The MAX3420 is a USB peripheral controller chip with an SPI bus. This page hopefully contains enough information to help you easily make use of the device in your projects. The MAX3420 provides a very simple approach to adding a USB interface to a circuit.....
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CRV-59AAE is 20" long by 9" wide by 10"high. It weighs a mere 33 pounds. It is at least 60 years old and in excellent condition. It represents some of the finest in miniaturized technology for its time. It uses an iconoscope tube as the imager. It contains....
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RCA made some of the first commercially available CCD chips. A CCD (Charge Couple Device) is a silicon solid state imaging device that replaces the vidicon tubes of the past. CCD`s are made up a two dimensional array of photo detectors coupled to an array of....
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This has been supplanted by the SD library built into the Arduino IDE. The only good thing about it is that it will (barely) fit and run into a `168 Arduino so if you happen to be stuck with a `168 and can`t upgrade, this code may be handy. Otherwise, please....
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There is a small power supply on the board for generating 3. 3V @ 250mA. We don`t use the `built in` 3. 3v regulator on the Arduino because its only guaranteed up to 50mA and some SD card need a lot of power when writing. This supply is nice and steady, we....
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Most metal detectors work on the fact that metals in a magnetic field change the behaviour of the field. There are two general approaches to detect these changes. In one approach, an alternating current is provided to a transmit coil. A receive coil is used....
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This is a write-up for a 2011 update to the 2008 lanc circuit project, lets call call phase 2. This update allows the use of a cx700v camera to be used in the same underwater video housing. Such a housing is called a generic housing. A generic housing....
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With a few basic hand tools and a digital camera, this programmable camera controller project is for you. By using components already available at home, costs may be kept to a minimum. A servomotor may be reused from a radio-controlled model and aluminium....
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ML2011GD/ML2011HB is MP3 decoder LSI easily used. Besides the MP3 decoder, it integrates stereo DAC and 8 © 650mW drive speaker amplifier that allows MP3 playback function only by building this LSI into the application...
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How to add an AC-3 RF output to older laser disc players. Finally I was ready to try it myself. Kevin Nakano`s web page (link below) was very helpful. His page describes how to do the modification to a CLD-D702. My CLD-1090 is very similar to the CLD-D702.....
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This modification is to be done AT YOUR OWN RISK and there is no guarantee that the modification will work for you. Failure to properly install this design correctly may result in damage to you and/or your laserdisc player. This web site takes no....
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The design is based loosely on some ideas from K8CU and AG6K. However, I have simplified the circuit somewhat and used different components. The mechanical encapsulation is also different. I used LTspice to verify the tester before building it. The schematic....
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The ARMSTRONG OSCILLATOR is used to produce a sine-wave output of constant amplitude and of fairly constant frequency within the rf range. It is generally used as a local oscillator in receivers, as a source in signal generators, and as a radio-frequency....
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The beat frequency oscillator (bfo) is necessary when you want to receive cw signals. Cw signals are not modulated with an audio component, you remember, so we must provide one. The action of the rf amplifier, mixer, local oscillator, and IF amplifier is the....
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Clocks have been mentioned in the preceding section with regard to their action with FFs. You will recall that this circuit is a timing signal generated by the equipment to control operations. This control feature is demonstrated in both the D and J-K FFs.....
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Another frequency-determining device is the CRYSTAL. The crystal may be used with a tank circuit, or it may perform alone. Crystals exhibit a characteristic known as the PIEZOELECTRIC EFFECT. The piezoelectric effect is the property of a crystal by which....
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The diode tube we are about to study is really Edison`s old incandescent bulb with the plate in it. Diode means two elements or two electrodes, and refers to the two parts within the glass container that make up the tube. Within a few years after the....
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The HARTLEY OSCILLATOR is an improvement over the Armstrong oscillator. Although its frequency stability is not the best possible of all the oscillators, the Hartley oscillator can generate a wide range of frequencies and is very easy to tune. The Hartley....
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Reverse the DC power connections on such a motor and its shaft will rotate in the opposite direction. One way to control direction is to use switches arranged in the following manner: This configuration is called an H-Bridge due to its shape. Let`s say that....
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The Hartley Oscillator is a particularly useful circuit for producing good quality sine wave signals in the RF range, (30kHz to 30MHz) although at the higher limits of this range and above, The Colpitts oscillator is usually preferred. Although both these....
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A typical Colpitts oscillator design. This circuit is very similar in operation to the Hartley oscillator described in Oscillators Module 2. 1 but the Colpitts LC tank circuit consists of a single inductor and two capacitors. The capacitors form in effect, a....
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Build the Colpitts oscillator shown using either breadboard (proto board) or strip board, then test the oscillator`s operation using a multi meter and oscilloscope. This Colpitts oscillator produces a sine wave output in excess of 12Vpp at an approximate....
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Where good frequency stability is required, in applications such radio transmitters, basic LC oscillators cannot guarantee to hold their frequency without some drifting, which can be caused by quite small changes in supply voltage (although stabilised power....
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A basic Wien Bridge Oscillator using a filament lamp with an op amp. It is a property of filament lamps that the resistance of the tungsten filament increases in a non-linear manner as the filament heats up. The lamp in Fig. 3. 4. 1 is connected in the....
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The basic bipolar transistor (BJT) version of an astable multivibrator as shown in Fig. 4. 1. 1 has two outputs that repeatedly change state at a rate determined by the time constants of its feedback network. Although largely superseded by its equivalent op....
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If an oscillator of a particular frequency and mark to space ratio is required, (see Fig. 4. 4. 1) the method would be to calculate periodic time from the required frequency and the discharge time and charge time using the formulae for tD and tC described in....
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The 555 timer is so named because its primary mode of operation is intended to be in monostable mode. Operating as a monostable, it does not fit the strict definition of an oscillator because, unlike true oscillators, it requires an input signal to trigger....
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In his circuit Marin has used two transistors wired as a high gain compound pair. Transistor T1 may be a 2N2222A and T2 a BC108. The current gain will be the product of each transistors beta, which will be a minimum of 140 x 110 or 15400. ..
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As you are probably familiar, an accelerometer is a device that can measure dynamic acceleration (vibrations) and static acceleration (gravity). Being that it measures this, it can measure tilts, rotations, and movements/lack-of-movements for alarm system....
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To do this, first, we must make the appropriate physical connections from the arduino board to the LCD. Then after, we must write the code so that whatever text we want displayed comes up on the LCD. LCDs are pretty much the standard now in order to display....
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For example, once the motion sensor picks up motion, we can program the arduino to turn on an LED, turn on a motor so that it spins, sound a buzzer off, etc. In this circuit we are doing here, for simplicity, we will simply turn on an LED once the motion....
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When doing DC analysis, all AC voltage sources are taken out of the circuit because they`re AC sources. DC analysis is concerned only with DC sources. We also take out all capacitors because in DC, capacitors function as open circuits. For this reason,....
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The hall effect sensor we will use in this circuit is an A1302 hall effect sensor manufactured by Allegro. This IC can detect magnetic fields. We will then connect this IC to an arduino, so that we the arduino can read the voltage output by the A1302 and we....
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With the 10KG potentiometer, you can vary the contrast from dark to bright. When the potentiometer is near 0G , the screen will be very dark. As you turn the potentiometer up to 10KG , the screen will become brighter. ..
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For this project, we`re going to demonstrate how a capacitor can supply a pulse signal to a speaker. We`re going to charge a capacitor and then discharge the voltage of the capacitor to a speaker. The speaker, a transducer which turns electrical signals into....
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The device we then build will function as a metal detector that can scout out metal objects, such as coins, nails, keys such as car keys you may not be able to find, and even gold if you`re looking for in a beach (though this one may not have industrial....
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In this project, all we do is hook up the positive side of the battery to the positive lead of the buzzer and the negative side of the battery to the negative lead of the buzzer. The positive lead of the buzzer many of the times is a red color and the....
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Now we will build a very simple photoresistor circuit to make a photoresistor do what it does: make the circuit work when there is light and stop working when there is darkness. For this circuit, we connect a photoresistor to an LED. When the photoresistor....
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In this project we`re going to use use two wires, in this project, we use one red and the other blue, which serve as the touch sensor wires. When a person touches both wires, the circuit is then closed and current runs through the circuit and lights the LED.....
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A differentiating circuit is a circuit that produces pulses or that fades out input waveforms from its peak value all the way down to zero. To show this visually, let`s view the waveforms, which will show the result of this project. So you can see the input....
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An equalizer is a device that allows you to adjust the gains of individual frequencies. You may want to lower bass, so on an equalizer, you would go to the frequency range of bass, which may be around 500Hz and turn down the volume. If you want to increase....
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In this project, we will build an audio mixer, which is a device that can add different audio signals together into one output. For example, say, one audio input is a cappella, with a personG ‚¬ s lone voice singing and another audio signal is background....
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Terminals 1 and 8 represent the gain control of the amplifier. These are the terminals where you can adjust the gain by placing a resistor and capacitor or just capacitor between these terminals. In this circuit, we will place a 10G‚ µF capacitor between....
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For this project, we are going to charge a capacitor with voltage and then have the capacitor act as a temporary power source for the circuit. After we charge the capacitor with the battery, we`re going to disconnect the battery from the circuit. The....
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This is a pretty simple project we are going to do. We are going to create a simple buzzer circuit where we can increase or decrease the volume of the sound that the buzzer outputs. Okay, now we can do this in two ways. We can first turn the potentiometer....
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You`ve probably seen many of these toys. They`ve been around for years, from the talking tickle me elmo to the talking furby, like the one shown above. How do these devices do what they do when you perform an action such as tickle them or press a certain....
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The 555 timer chip is a very versatile IC, because when connected correctly, it can it can create pulses of current at specific time intervals decided by the resistor-capacitor (RC) network. When a 555 timer creates pulses in this way, the LED doesn`t stay....
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Unlike LED light, a laser`s light output is more concentrated, meaning it has a smaller and more narrow viewing angle. This means it must be directed at its source more directly in order to be picked up. Laser light is also monochromatic, meaning laser light....
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This is a circuit that will go off once it detects a certain amount of light. Once the light the circuit is exposed to increases to a certain level, a loud buzzer will go off, alerting us to this. So the alarm will not go off when the circuit is exposed to a....
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This is an alarm circuit which will go off when any motion or movement is detected. Once it detects this motion, the circuit will trigger an alarm buzzer to sound which will remain on until the power is disconnected from the circuit. This alarm circuit`s....
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This is a circuit which can detect any motion or movement. It`s most common use is to detect a person moving through an area where the motion detector can sense. The main electronic component we will use that allows us to pick up this detection is the PIR....
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Many people place motion detectors in their backyards or even in their houses so that when they walk through that area, the lights will automatically turn on. Thus, motion sensor lights are very popular and being increased in use. Businesses use them all the....
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An overvoltage protection circuit is a circuit which protects electronics from excess voltage, which could potentially damage or destroy electronic components. In this project, we will build a simple, yet effective, overvoltage protection circuit using a....
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There are 2 ways to build a protximity detector. One is mount the IR LED and the phototransistor so that they face each other. Then the infrared light is detected by the phototransistor. If an object comes between the IR LED and the phototransistor, the....
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In this project, we will build a relay driver for both DC and AC relays. Since DC and AC voltages operate differently, to build relay drivers for them requires slightly different setup. We will also go over a generic relay driver which can operate from....
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This is a circuit that will go off if the circuit detects any sound above a certain threshold. Once the circuit detects sound, the alarm goes off alerting us to this sound. This circuit has extreme use when an area ordinarily should be very quiet and should....
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The IC we will use to measure the temperature is the TMP36 IC. We will integrate this with the arduino to measure the temperature. The arduino will then read this measured value from the TMP36 and translate into degrees fahrenheit which we will be able to....
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This is a circuit where an alarm will go off once the circuit is tilted. Once the circuit is tilted beyond a certain degree, a loud buzzer will go off, alerting us to this. Many different types of electronics have tip-over protection circuits. One such....
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This alarm can be very useful in a room or an area that should normally have no movement at all in it. In a totally still room with no movement, no vibration will be detected and the alarm will not go off. Once the circuit detects a vibration, which could....
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The sensors are a thin strip of piezoelectric material with a rivet in the end acting as a weight. When there is a vibration, the weight moves, stressing the piezo material that produces a spike in voltage. This voltage that is created may be up to 90V. We....
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If resistors R1 to R4 are variable, the signals can be mixed in any proportion, meaning at any volume levels. And overall volume can be set by a variable resistor in series with Rf. ..
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This design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9. 5 -....
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This circuit idea is certainly not new, but when it comes to making a trade-of between using a small, short-circuit proof transformer or a capacitive voltage divider (directly from 230 V mains voltage) as the power supply for a fan, it can come in very....
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Fluorescent tubes use far less energy than incandescent lamps and fluorescent tubes last a great deal longer as well. Other advantages are diffuse, glare-free lighting and low heat output. For these reasons, fluorescent lighting is the natural choice in....
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Most small internal-combustion engines commonly used in the model-building world use glow plugs for starting. Unfortunately, glow plugs have an operating voltage of 1. 5 V, while fuel pumps, starter motors, chargers and the like generally run on 12 V. This....
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Lead acid batteries often fail prematurely due to over-charging, under-charging, deep discharging and low electrolyte level. All of these can lead to sulphation of the plates which leads to high internal resistance and eventual failure. Normally, this....
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When running 12V electronic devices from lead-acid battery banks, the voltage to the appliance can vary from below 11V with discharged batteries, to well above 14V during charging. Many appliances will not tolerate such a wide fluctuation and may perform....
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This handy circuit can be used as a speed controller for a 12V motor rated up to 5A (continuous) or as a dimmer for a 12V halogen or standard incandescent lamp rated up to 50W. It varies the power to the load (motor or lamp) using pulse width modulation....
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The TDA8581(T) from Philips Semiconductors is a 1-watt Bridge Tied Load (BTL) audio power amplifier capable of delivering 1 watt output power into an 8-Wload at THD (total harmonic distortion) of 10% and using a 5V power supply. The schematic shown here....
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This circuit is designed to drive the 1W LEDs that are now commonly available. Their non-linear voltage to current relationship and variation in forward voltage with temperature necessitates the use of a 350mA, constant-current power source as provided by....
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This unit is intended to be connected to an existing car stereo amplifier, adding the often required extra "punch" to the music by driving a subwoofer. As very low frequencies are omnidirectional, a single amplifier is necessary to drive this dedicated....
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The circuit was deliberately designed using no ICs and in a rather old-fashioned manner in order to obtain good harmonic distortion behavior and to avoid hard to find components. The amplifier(s) can be conveniently supplied by a 12V wall plug-in adapter.....
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This project was a sort of challenge: designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality. The Power Amplifier section employs only three transistors and a handful of resistors and....
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Many modern circuits tend to work from a single supply voltage of 3V. But often they need a virtual earth at half the supply voltage for efficient operation. The splitter shown in the diagram bisects the supply voltage with a high-resistance potential....
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This design will interest technicians who work on pneumatically operated valves and other 4-20mA current loop controlled devices. Although 4-20mA signal injector/calibrators are available, this one is both cheap to build and easy to operate. When first....
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The operation of the converter is based on the weighted adding and transferring of the analogue input levels and the digital output levels. It consists of comparators and resistors. In theory, the number of bits is unlimited, but each bit needs a comparator....
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The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs. The....