Popular Circuits Page 79
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The goal is to be able to turn on and off the load (an 8051 based uC) by pressing both switches. When the uC turns on, it sets PWR high, and then when the switches are pressed again, pin 4 of the flip flop goes low, turning off the boost regulator and uC.....
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The design of solar panel systems with a (lead-acid) buffer battery is normally such that the battery is charged even when there is not much sunshine. Thi....
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The design objective was to produce an hFE tester with switched collector currents for the DUT (Device Under Test) covering a range suitable for the selection and matching of output transistors for amplifiers such as the JLH Class-A, ESP DoZ etc. The tester....
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If we have a lot of parallel telephones on a telephone line, we needed a unit that will have the possibility of showing if somebody of the telephone has raised the earphone. Our this possibility give the circuit. The circuit is connected at parallel with the....
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Unusual frequency compensation gives this logarithmic converter a 100 µs time constant from 1 mA down to 100 µA, increasing from 200 µe to 200 ms from 10 nA to 10 pA. Optional bias current compensation can give 10 pA resolution from - 55 °C to 100 °C..
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This sketch sends an ASCII A (byte of value 65) on startup and repeats that until it gets a serial response from the computer. Then it sends three sensor values as single bytes, and waits for another response from the computer. You can use the Arduino serial....
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Below that is the clock section. The knob controls the internal oscillator`s speed, and that can be voltage-controlled via the `Speed In` input. Or, you can insert your own clock signal via the `Clock In`. This is slightly unusual, but I think having the....
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Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances. This remote control unit has 4 channels which can be easily extended to 12. This circuit differs from similar circuits in view....
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4 ~ 20mA constituted by a TMP35 temperature transmitter circuit as shown in FIG. This circuit can be a voltage signal TMP35 output is converted into a standard 4 ~ 20mA current..
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This page describes my home-built ICOM CI-V interface. In order to connect most all ICOM radios to a computer, an additional interface is required. The interface bridges the gap between the RS-232 electrical levels used by the computer serial port, and the....
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Here`s the circuit for a simple electronic delay detonator circuit diagram. The overall circuit is in a hybrid IC module. This is the figure of the circuit; The diode-bridge circuit connected to the input terminals, a power supply capacitor connected to the....
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This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range. It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a....
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The power supply has been simplified. Power transformers and rectifiers have been omitted and some parts have been omitted from the MOSFET voltage regulator circuits: 1N5242 zener diodes between the source and gate and 10k resistors in series with the gate.....
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A number of shunts and multipliers selected by a switch can be used in association with a single basic meter to form a multirange instrument, known as a multimeter. this is capable of measuring volts, current and resistance. A multirange meter can be....
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Add a simple, low-cost, jack-sensing circuit (JACKSENSE) to a DirectDrive automotive headphone amp and detect when a headphone is inserted into the audio jack....
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In some places, allowing only a specific direction by the motor running, even when the power supply phase sequence..
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This novel buzzer circuit uses a relay in series with a small audio transformer and speaker. When the switch is pressed, the relay will operate via the transformer primary and closed relay contact. As soon as the relay operates the normally closed contact....
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The LCD display on my NAD C520 compact disk player has become unreadable. The audio and CD deck are operating fine but operating the unit without a legible displayis difficult. If you look at the LCD under the right external lighting you can see that the....
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This laser door alarm is based on the interruption of Laser beam. A low cost Laser pointer is used as the source of light beam. When somebody breaks the la....
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Input terminal VIN is connected to the +V line of tbe circuit that the indicator is to monitor, and the grounds of botb circuits are connected togetber. The position of potentiometer Rl"s wiper determines Q1"s base voltage. As long as the transistor....
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TI`s Dafydd Roche completes his 4-part series on sound-bar design with a detailed explanation of clock design for the digital portion of the circuit..
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This is a circuit for voice transmitter using a pair of BC548 transistors in this circuit. Although not strictly RF transistors, they still give good results. I have used an ECM Mic insert from Maplin Electronics, order code FS43W. It is a two terminal ECM,....
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This relay driver boosts the input impedance with a regular BC547 NPN transistor (or equivalent). Very common driver. It can drive a variety of relays, including a reed-relay. Transistor Q1and Q2 are a simple common-emitter amplifier that increases the....
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It`s basically a standard Hartley oscillator, output is +7 dBm into 50 Ohms. Don`t be tempted to add a gate diode, this circuit doesn`t need it, and it will degrade the phase noise performance, according to Ulrich Rohde. It should be suitable for any....
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This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer. This circuit takes it power from a PC. The power....
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This circuit is built around a 555 timer using very few components. Since the circuit is very simple, even a novice can easily build it and use it as a controlling device. A laser pointer, now easily available in the market, can be used to operate this....
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Back in the day when AM was king, no expense was spared on transmitting equipment. I remember the GE BTA-25 transmitter from the same era, it was build like a tank. Once, while we were repairing the Harris MW-50A main transmitter, the old GE burped,....
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A regenerative radio works by feeding back a small amount of amplified output of the detector back into the input. Thus it achieves sensitivity far beyond what only a detector could alone. This simple regen radio uses a single tube as it`s detector and....
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This circuit is an oscillator, and is able to generate a sound wave, a tone. The tone`s frequency (if it`s a high or low sound) is controlled by the variable resistor. The sound volume of this circuit is considerable so, don`t put your ear too close to the....
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It is recommended to Have a Fuse in the Power Line and to always have a Load connected , while power is being applied. The Fuse should be10 Amps per 100 watts of output. The Power leads must be heavy enough wire to handle this High Current Draw...
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The LME49830 EF125WT1 amplifier PCB module showcases National Semiconductor s LME ultra-high fidelity power amplifier input stage ICs (drivers). The LME49....
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CGS-H ceramic humidity sensor constructed low humidity detection circuit diagram . ..
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Based on NE555 this circuit turns on and off the IC output by a momentary switch. In other words it works as a mechanical latching relay, but the circuit backs to the start condition when you switch off the power supply. This feature is often required in....
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Figure 1 shows a circuit for sensing the water level in a tank and turning on or off a water pump accordingly. The main component of the circuit is the CD-4011 Quad NAND gate, three gates of which are used as shown in Figure 1 (gates G1, G2, and G3). G1 is....
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A simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i. e. at low frequency, period is measured for a complete wave and....
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The use of diode rectifiers in AC voltmeters with a low lower limit of measurement range (0. 5. 1 V) leads to significant nonlinearity of the scale because of the nonlinearity of current-voltage characteristics of diodes. The use of electronic amplifiers in....
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32.768kHz ; In MP3/MP4, mobile phones, laptops and other digital products are provided real-time clock signal generating circuit, which is shown in FIG example, and is mainly c..
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Easy to build high-quality PLL FM transmitter with typical output power of 5 W and no-tune design. The transmitter includes RDS/SCA input and Audio/MPX input with optional pre-emphasis. It can be used with or without stereo encoder. Tuning over the FM band....
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This circuit is a basic theremin with only a pitch control. It uses the "heterodyne" technique, as did Theremin`s original instrument. Heterodyning is advantageous in its simplicity, and is made further attractive in this design by eliminating the coils that....
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The two neon bulbs will light when more than 100 V is across the ringing circuit. The bulbs provide line isolation between the unit and the telephone line. Finally, they act as a voltage divider for the bridge rectifier made up of D 1 through D4. That....
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This circuit bellow shows a teleremote circuit which enables switching ‘on and ‘off of appliances through telephone lines. Can be used ....
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U1 is a 3817 integrated circuit, which is produced by Fairchild Corp. It can directly drive the display, and it can display for 12h or 24h, It can generate the clock sound and turn on the radios on time. The display is a FND500 LED, the input frequency can....
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When power is first applied, three things happen: light -driving transistor Ql is switched on due to a iow output from U2 pin 3; timer U1 begins its timing cycle, with the output, pin 3, becoming high, inhibiting U2"s trigger, pin 2, via D2; and charge....
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This circuit diagram is a UM66 based touch sensitive musical bell. The circuit is built around CMOS IC CD4011 and popular melody generator IC UM66. The circuit contains a pair of touch plates. When these are bridged by hand for a moment, the um66 starts....
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With this electronic dice the result is displayed with LEDs that are placed so every dice face is shown. In the circuit diagram, IC 4022 is used to count t....
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This Arduino sketch is useful for rescuing ATtiny microcontrollers rendered useless by incorrect fuse settings. It does this by putting the bricked tiny into high-voltage serial programming mode and writingthe fuses to safe values. The Arduino is connected....
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To get a low output impedance I needed to use quite a high step-down ratio (20:1); after all, the amplifier may be used with headphones of lower impedance that the 300 Ohms of the HD600. The output valve is the 12B4A which has a anode impedance of about....
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While laying in bed and watching movies on my laptop, I used to think if there is a remote control, it will be easy to pause, play, fwd, rev, adjust volume, play next etc etc without going near to the system. Then I planned to make a remote control. I don`t....
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This circuit will convert a positive voltage to a negative voltage, while losing 1. 5 V (approximately). For example, if you`re supplying 9V to the circuit, the output will be -7. 5 V. This circuit can also be used as voltage doubler, by using the output as....
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Many times we have found itself in the necessity to use a Zener diode and cannot to know the voltage of operation. Many times we cannot read the characteristics or the type that is written on her. In this case, but in different we can also use the circuit....
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This is a 1-amp variable-voltage PSU. It adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment...
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Even as display devices move toward digital video, they retain the legacy of an RF-modulated analog TV output. That output is specified in the US by the National Television Standards Committee (NTSC), and utilized in security applications and in the Digital....
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The EUA2123 is a high efficient Class-D Audio power Amplifier for delivering up to 2G—20W into a 4 stereo mode with a single-ended (SE) configuration or 1G—40W into an 8 mono mode with a bridge-tied-load (BTL) configuration. The high efficiency of the....
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This circuit switches a printer s USB connection from a PC to a laptop. What was needed was a method of allowing a laptop to use the printer occasionally....
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The microphone preamplifier circuit design presented in this schematic use SSM2015 produced by Precision Monolithics Inc. (PMI) which offers a high amplifi...
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The pilot detector output is designed as an open collector output, therefore an external pull up resistor is needed. To force the decoder to "MONO" Pin 19 has to be clamped to a voltage below 0. 8V...
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All optical transmitters will contain circuitry to limit the current to a value that will be safe enough to protect the LED during short-term accidents. Red, Red-Orange, and Amber Luxeon I LEDs have a much lower peak current rating - about 550 mA. At this....
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This is a very simple and easy to make IR receiver circuit. This infrared receiver circuit is using only few components and it is able to receive 38KHz carrier signal. The working of this circuit is simple when ever the IR LED receive any signal from 38KHz....
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This is the electronic schematic of the homebuilt SONAR. Only one piezoelectric tranducer is used for both tramsmit & receive. This transducer is switched from TX to RX via the four 4016 switches. A high gain amplifier stage & rectifier translates the....
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A safe home is a happy one, but many off-the-shelf surveillance cameras are too expensive or simply impractical for home use. That`s why designer Alberto Ricci Bitti created an automated and inexpensive surveillance camera that uses a flash card as recording....
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The input resistance of a. c. -coupled op amp circuits depends almost entirely on the resistance with which the d. c. setting is determined. If CMOS op amps are used, the input resistance is normally high, currently up to 10 M. If a higher value is needed, a....
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The LM231 LM331 family of voltage-to-frequency converters are ideally suited for use in simple low-cost circuits for Analog-to-digital conversion, precision frequency-to-voltage conversion, long-term integration, linear frequency modulation or demodulation,....
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The ISL6323 dual PWM controller delivers high efficiency and tight regulation from two synchronous buck DC/DC converters. The ISL6323 supports hybrid power control of AMD processors which operate from either a 6-bit parallel VID interface (PVI) or a serial....
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I use the lm10 IC because it has a reference voltage and that`s useful for dc power supply. With two ICs can take different output voltage and amperage. This circuit is protected from short circuit. P2 is for controlling the current at the range of 0-2A.....
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An 30 Watt audio amplifier circuit with TDA2040 shown here. TDA2040 is class AB amplifier monolithic integrated audio Pentawatt available in the package. The IC has a low harmonic distortion, cross low over the distortion and has a built in short circuit....
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This is the circuit diagram of a very sensitive electromagnetic field sensor which can sense electromagnetic field from 40Hz to 140Hz. The low noise opamp LF351 and associated components forms the pick-up section. 1uH coil L1 is used for sensing the field....
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This circuit is very basic to build. To open a the lock which is connected to the K1 Load you must press each momentary switch in the correct sequence. The sequence used in this circuit is S1,S2,S3,S4. If any of the other switches are pressed the circuit....
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This circuit is designed to operate an electrical door-release mechanism - but it will have other applications. Enter the four-digit code of your choice - and the relay will energize for the period of time set by C4 & R4. Use the relay contacts to power the....
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555 Timer enables low-loss single-shot circuit and CMOS4011B NAND gate circuit interface. Standby power consumption of less than 50 A. When the one-shot circuit is turned on, t..
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In this instructable I`ll show you how to build a detachable solar panel and battery charger for your backpack. This can power or charge all your gadg....
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The basic current allows no carrier to be present in the output. By adding offsets to the carrier differential pairs, controlled amounts of carrier appear at the output. The amplitude becomes a function of the modulation signal-AM modulation. ..
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In some electronic applications we need to switch or control high voltages or high currents. In these cases we may useelectromagnetic or solid state relays. For example, it can be used to control home appliances using low power electronic circuits.....
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Both help improve efficiency and protect micro-inverters in PV solar applications In 2009, the residential solar photovoltaic (PV) inverter market represented 90 percent of the total PV....
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Typical circuit representative of those used in most light switch type digital timers. The timer module is normally a PIC or custom chip, and it syncs to the AC line so that a trigger pulse can be supplied at the right moment...
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Using the principles of a horizontal steam engine I constructed a model in which the steam cylinder is replaced by an electromagnet with a moving core. The construction details of the model are of little importance, as the photos give all the information you....
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Desheng 89701 type radio (small shortwave Wang) circuit diagram is shown below: ..
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This circuit shows a simple method of achieving a voltage reference which can be trimmed using an 8bit DAC with an on-chip voltage reference. The analogue output from the DAC drives the trim pin of the ZNREF025 via a resistor, R,. When Rs = 0, this circuit....
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The push button and potentiometer initiate a time delay that turns a light on then automatically turns it off again after a predetermined time. The potentiometer can be set for a delay of a few seconds to just under three minutes. When the push-button switch....
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The following experiment shows how interestingly Mr. Steven could draw free energy from air using his home-built sec exciter coil tower, he used it to a feed a small LM317 power supply unit and made it work successfully. Read more. "When i hand wind my coils....
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So there is a chance to use them in combination with a condenser microphone amplifier for a VLF Receiver. Bingo. The first tests as a Monopole gave good results. I live in a small town located at J041VG with approximately 7500 inhabitants. The height above....
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This paper gives a practical example of the design of an off-line switching power supply.
Factors governing the choice of a discontinuous flyback topology are discussed. The design
uses a pulsed-width modulation (PWM) control scheme implemented....
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WHY is the voltage at 12V after the emitter If it`s coming out of the op amp at +15V, then that would put a 3volt drop across the transistor. and why isn`t the gain 2, shouldn`t there be 8 volts coming out to the transistor In that case wouldn`t a 4volt drop....
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FM Wireless Microphone Schematic. In some applications, the use of the microphone cable is sometimes very difficultly. So use a cordless microphone is needed. Microphone as it is often referred to as wireless microphones (cordless microphone). Here I share....