Top Circuits Page 209
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Circuit of a loop sensor based simple security alarm is described here. The sensor loop is nothing but a short length of thin enamelled copper wire, which....
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This electronic cricket is a present for Kids. This simple battery powered circuit can be used to play Cricket Match with your friends. Each LED in the cir....
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The power switch with infrared proximity sensor is intended for the recognition of obstructions at distances of a few millimetres to a few centimetres. Thi....
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This Simple circuit can monitor overflow of water from the Overhead tank. The sensor placed close to the lid of the overhead tank always monitor the presen....
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The common home solar power system, in principle consists of a roof-mounted solar panel, a charge controller and a storage battery bank plus direct or elec....
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Most universal radio receivers have a very wide bandwidth that is not particulary for radio amateurs. The better models with narrower bandwith are almost a....
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Ever accidentally left your front door ajar and had a pet escape Here is a smart solution to this problem. The circuit is fairly simple but a great example of using a tiny circuit to get the job done. All you need is a CD4011 IC plus a handful of components.....
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This time delay relay circuit is built with IC NE/SE555, produced by Intersil which contains a precision timer. Stability to temperature variations is 0.00....
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This is a 35.3 to 10.7 MHz converter circuit. It converts the 35.3 MHz signal coming from a VHF/UHF tuner down to an FM tuner to decode the TV audio in FM....
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This 3 band equalizer circuit is an active filter network for bass, mid and high audio ranges. It is designed around the LM833 opamp from National Semiconductors. The output of this 3 way graphic equalizer is designed to be DC coupled, however due to slight....
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This audio processor circuit features the SSM2045 IC which was developed specially for electronic music applications and the 741 opamp IC. The circuit is c....
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This 555 timer is designed unusually to give a positive output through a control over its reset pin. Usually the timer IC 555 is triggered by applying a ne....
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An interesting circuit of a true-portable and cute solid-state bright light built with LT1932. The light can be operated from two AA size dry/rechargeable pen-light cells. There is no housing included so that you can use your own imagination as to what you....
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This circuit uses invisible infrared light to detect the movement of people through the door. A short beep will be generated when the infrared beam breaks ..
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AVC - The featured circuit controls a volume line automatically. It delivers an output voltage of approximately 4 volts peak to peak. This voltage remains....
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This humidity controlled switch circuit turns on and off an electrical load (for example a heater) depending on the moisture content of the surrounding air....
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A very interesting remote controlled alarm circuit using TSOP1736. Routing of an electric cable to attach a calling bell switch near the bed of an old age/patient is not a good idea. Here is an ultra simple battery operated remote controlled alarm to help....
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Most of the battery chargers do not have current and voltage regulation provisions. The step down voltage is simply used for charging. These chargers devel....
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The high temperature alarm will beep and LED blinks when the temperature of the device increases abnormally. This simple over heat alarm is to monitor heat....
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Using this simple Christmas LED lights decoration circuit, you can make an 18 LED flasher to decorate the Christmas Tree. The White, Blue and Red LEDs flas....
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Here is a simple power resumption alarm circuit that can be fixed inside the switch box itself. It gives beeps when the power resumes after a power failure....
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One advantage of solid-state relay (SSR) over conventional electro-magnetic relay (EMR) is its tear and wear free operation. S201S01 from Sharp is a good e....
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Without any dedicated buck converter/white LED driver IC, you can safely drive many standard Hi-efficieny white LED modules using the battery power availab....
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A simple light fence security beeper is presented here. This circuit can be used as a door alarm, gate alarm, pathway alarm, etc. Any 12 Volt dc power supply can power the whole circuit. Working of this circuit is straight forward. In standby mode photo....
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Here is a simple LED blinker or flasher for decoration purpose. The 20 High bright LEDs flashes alternately giving a brilliant colour display. The circuit....
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One of the serious problems in relay operated circuits is the relay clicking or chattering during the on/off of the relay driver transistor. This problem i....
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Here is an ultra simple automatic light switch circuit for bedrooms. After construction, connect the input terminals of this circuit in parallel to the int....
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Here is one basic circuit of a simple but accurate 1Hz timebase generator built around a standard Quartz clock circuit board. Just lift the clock PCB from....
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This easy to construct Handy pen torch electronic circuit and low component count, uses two power white LEDs for lighting. Low volt (4. 8V dc) supply available from the built in rechargeable Ni-Cd battery pack is first converted into two channel....
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This LC meter circuit can measure coils and capacitors. When Lx or Cx is connected in the circuit the oscillator frequency will decrease and this decrease is measured by a frequency-voltage converter build with T3 and T4. To adjust this lc meter circuit with....
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Most of the PC desk lamps available in the market light up whenever there is an input power. These don`t take into account whether there is a real need for....
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An interesting hobby circuit of a crank door bell! The circuit is built around a timer 555 and a musical piezo-buzzer. The circuit works off 9 volt battery supply. One 9volt PP3/6F22 compact battery is enough for powering the whole gadget. Timer IC (NE555)....
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This is a simple magnetic levitation circuit which suspends objects a set distance below an electromagnet. The physics behind it is to simply provide a mag....
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As the name indicates, the step switch selector circuit is intended to choose one of up to four analogue switches, which it does with the aid of some less....
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Exhaust fan is an important component in kitchens. Here is a simple circuit to control kitchen fans by monitoring the ambient temperature. It is built arou....
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The most simple polarity protection tehnique is to connect a series diode to the power line input. The diode conducts only when the power supply protection....
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The principle used in this electronic head or tail circuit is simple: a multivibrator controls a flip flop. The multivibrator oscillates as long as the buton S1 is pressed and the flip flop switches on and off with a frequency of several kilohertz. When the....
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This musical light alarm circuit is very simple, uses only 7 components, a LDR and a 3. 6 V battery or 3 x 1. 2 volts rechargeable batteries. The well-known UM66 is used as the sound generator and will give a pleasent wake up alarm. As you probably know the....
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This dc voltage doubler circuit produces a voltage that is twice its voltage supply. This is useful when a higher voltage level is needed out of a single lower voltage power supply. Since the current consumption levels are low in such cases, the circuit can....
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4013 dual D-type flip-flop is a monolithic complementary MOS (CMOS) integrated circuit constructed with N- and P- channel enhacement mode transistors. Each....
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This is a simple arduino project for a soil moisture sensor that will light up a LED at a certain moisture level. It uses Arduino Duemilanove microcontroll....
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This is a very simple square wave generator circuit built with IC 74LS00 that can generate square signals with frequencies between 20 Hz and 1 MHz. Its stability is good enough for most applications. The output freq. is dimensioned through the RC components....
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This audio amplifier circuit delivers up to 200 W of top-class quality for loudspeaker from 4 to 16 ohm. Operating voltage is between 24 and 36 V, max 5 A ..
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Starting from a 30 volt power supply this high voltage converter circuit can deliver a voltage between 0 to 3 kV (version 1) or from 0 to 10 kV (version 2)....
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This electronic lie detector circuit project will give two readings: one for difficult questions for the subject and another to show its emotional state in....
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This battery charger circuit can be used to charge one or more batteries with the total nominal voltage of 12 V, meaning ten NiCd battery or six 2 V lead a....
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When loading a battery during the day from a solar panel it can be partially discharging through the panel after nightfall. This solar panel power switch circuit replaces the diode and connects the panel to battery through a relay contact. When the voltage....
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A RF probe is a circuit for testing equipment that converts a high frequency signal into a DC voltage. In this way it is very easy to measure RF voltages for either testing or adjustments of transmitters, receivers, modulators. The RF probe circuit described....
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This light sensitive automatic light switch circuit is intended to be connected at the main 220V supply. The circuit will connect a 220V lamp at the nightf....
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This light sensor switch circuit allows the automatic connection of a lamp when the light is low (at nightfall) and will maintain the lamp ON for a certain period of time. From the moment that T4 and T5 are opened, relay`s LED start to light and powers the....
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This sensitive touch potentiometer is based on IC1 (CA3130), one operational amplifier with a high input impedance. When the finger touches Se1 sensor, C2....
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With IC SLB0586A from Siemens you can build a simple touch light dimmer circuit that will allow you to adjust the lamp intensity. Together with a TIC206D triac, it enables smooth regulation of light intensity from a bulb of 10W 400W. A coil of 100 µH/5A is....
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This temperature controlled relay circuit is a simple yet highly accurate thermal control circuit which can be used in applications where automatic tempera....
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This homemade metal detector circuit will help you find objects composed of materials with relatively high magnetic permeability. It is not suitable for bu....
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If you know some language of programming as C +, PASCAL, VISUAL BASIC, DELPHI etc you can write a program which will send in the parallel door (378 I) of PC a number from 0 until 255 checking thus the tendency of expense of simple D/A of converter (that it....
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This simple water detector circuit uses alternative voltage in order to prevent the corrosion of the electrodes. It is easy to build and uses N1 as a trigger Schmitt gate which generate the AC. If between the electrodes is a electricity conductor, for....
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This is a simple home telephone ringtone generator circuit which is built with applying only several electronic components / parts. It generates simulated telephone ringtone and requires only DC supply with 4. 5V DC to 12V DC voltage. One may possibly use....
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A gas leak detector circuit that detects the leakage of LPG gas and alerts the user through audio-visual indications. The circuit operates off a 9V PP3 battery. Zener diode ZD1 is used to convert 9V into 5V DC to drive the gas sensor module. The gas leakage....
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You probably know that LM317 IC is used as an adjustable voltage regulator, but did you know it can be used as an audio amplifier? This is a class A audio....
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This sound level meter circuit can be used to control the intensity of a sound recording or in a disco. It has 5 measurement domains between 70 and 120 dB;....
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Use this cell phone charger circuit and a 1.5V battery when you do not have main power and need to charge your phone ..
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This simple LED driver circuit allows us to drive up to seven LEDs by using a single NiMH (Nickel Metal Hydride) AA cell. The circuit produces voltage puls....
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Butterworth filter is a filter whose freq response is flat over the passband region. British engineer Stephen Butterworth first described this ..
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In pulse position modulation, the amplitude and width of the pulses are kept constant, while the position of each pulse with reference to position of reference pulse, is changed according to the instantaneous sampled value of the modulating signal ..
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Attention! This strobe light circuit is connected to 220V, so measurements and experiments are very dangerous even after unplugging it from the mains. P1 p....
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Below shown circuit will be automatically switched ON and OFF during night and morning times respectively. In above circuit R1 can be used to adjust the sensitivity. And the working of the circuit is very simple. The LDR will have very low resistance during....
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This 3 volts Car Adapter circuit is based on a standard LT1074CT switching regulator IC. The schematic shows the LT1074CT used as a positive step-down or ‘....
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The best Op-Amp circuit which is used to convert sine waveform into rectangular waveform is the schmitt trigger circuit ..
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This transmitter is basic but allows transmission of audio to an AM radio. It consists of an RF oscillator operating in the AM broadcast band, together with a modulator stage, which mixes the incoming audio and the RF ..
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The car battery charging current is automatically limited to 4. 2A. If there is a 600mV voltage on R1 (4A thru it), then the T1 transistor starts to conduct. Excessive charging current is avoided because the current value on T3 ²s base is limited. The....
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This simple temperature relay circuit can be used to signal a fire or setpoint for temperature monitoring function. You need to adjust P1 so that T1`s base....
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This 12V SCR battery charger circuit differs from the norm in a number of ways, all of which make it difficult to understand ..
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Efficient automatic solar garder lights circuit with minimum components the best deal is that is completely auto and the Solar panel acts as a light detect....
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This battery level indicator offers (5) LEDs that light up progressively as the voltage increases: Red: Power Connected (0%) Yellow: Greater than 10.5V (25....
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Have your already set up a Christmas tree in your house and decorated it with traditional lights? Build a couple of these led lights to enhance the Christm....
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The light activated switch circuit can be used for switching OFF a particular lamp or group of lamps in response to the varying ambient light levels. The u....
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This is the most simple and affordable solar battery charger that the hobbyist can make. It has a few drawbacks over other similar controls, but offers numerous advantages. It is intended for charging lead-acid batteries, but may also be used for charging....
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This Low Dropout Voltage (LDO) solar charge controller uses a simple differential amplifier and series P channel MOSFET linear regulator --their compatibil....
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This is simple circuit that illustrates the function of the programmable unijunction transistor. It may be quickly wired on a proto-board. PUT Flasher Spec....
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This is a simple update to Mr. Hareendran`s PIR Sensor Security Light circuit. It has a shortcoming limits the relay voltage to approximately 3. 3V. While this may function with some 5V relays, it will not function with all. The nature of an emitter follower....
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I had heard some stories in the past concerning how poorly the 555 ran below Vcc = 5V, so I embarked on an endeavor to see if I could improve operation. Th....
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This is a take-off on Mr. Marian s ""Simple Micro Ampere Meter Circuit"" that utilizes active circuitry and an analog meter to make sensitive DC current meas....
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Here is a simple oscillator circuit that varies the duty cycle over a wide range without affecting the frequency. It is a variation of the simple 555 astab....
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This voltage converter is built with TL497A and converts an input voltage of 5 12 voltage to a higher level of 15 30 volts. This is specially helpful i....
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4 simple 12V power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you....
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The circuit is a precision integrated temperature sensor type LM35 (IC1), which provides an accurately linear and directly proportional output in mV, over the zero to +155 degrees C temperature range. This can be used as part of fire smoke detectors but do....
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This simple 220V power interface is intended as an interface for monitoring electric equipments and devices using a computer. The interface only senses whether the device being monitored is turned on or off. The most important aspect of the circuit is the....
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The heart of this diy metal detector circuit is the CS209A IC. The metal detector is built with one 100µH coil that has 40 mm in diameter and is made....
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There are many people who want to listen whats going on in VHF 108 - 132 MHz. This vhf am converter converts a band between 106 and 150 MHz, so you can lis....
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This universal power supply contains, beside the bridge rectifier, a voltage stabilizer (78xx) and a pnp power transistor. This combination allow a load cu....
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This overvoltage protection or crowbar protection circuit is used where we need protection against high voltage surge. The circuit has a few components, it....
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The diagram shows the circuit of a versatile USB power socket that safely converts the 12V battery voltage into stable 5V. This circuit makes it possible t....
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This is a cheap DC Voltage Doubler Circuit diagram, which requires a few components and will deliver 10V from a 5V power supply. If the oscillator must be....
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This Adjustable Voltage Regulator is made by combining a common 78L05 with an integrated audio amplifier of the type TDA2030, an adjustable voltage regulat....
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Here is a simple 12 volts DC to AC inverter circuit. This 120V AC power source is built with a simple 120V:24V or 110V:24V center-tapped control transforme....
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This 3V to 24 volt variable-regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3....
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With this sound activated switch, control by sound may be very useful, not just on a robot but also for a bit of home automation, for example a sound-activ....
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Whenever I use the 555 timer, it seems that the output polarity is invariably incorrect, and the way the 555 functions, it normally cannot generate a duty cycle of less than 50% ” 90% yes, 10% NO! This inverted 555 circuit generates duty cycles of less than....