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You can use this laser-based intruder alarm conveniently at the entrance of a hall or any other similar location to protect the same from unauthorised access as and when desired. Its range can be extended further to protect the perimeter of a  building from unauthorised intrusion by using a cascade arrangement of multiple alarms. The circuit consists of a transmitter and a receiver. Circuit diagram : Fig. 1: Transmitter circuit Diagram The transmitter circuit (shown in  Fig. 1) is nothing but a laser diode (LD1) driven by a 9V PP3 battery. The  output of IC1 is regulated 5V as long as  its input remains equal to or more than  7.5V, thus ensuring a constant drive  current for the laser diode. The battery (Batt1) is connected to the circuit  through switch S1. The laser diode (LD1) can be  replaced with a laser pointer (torch)  emitting red laser beam. The laser  pointer itself can be used as a transmitter. The pointer has in-built series  resistance, on/off switch and battery. Ci...

INTRODUCTION TO DARLINGTON PAIR In practice, the two transistors are put inside a single package and three terminals E, B and C are brought out as shown in figure. This three terminal device is known as darlington pair. It acts like a single transistor that has high current gain and high input impedence. DARLINGTON AMPLIFIER Darlington amplifier with voltage divider bias is shown in figure. In this circuit the output of one amplifier is coupled into the input of the next one by directly joining emitter of one transistor to the base of Other. Obviously, the emitter current of the first transistor becames the base current for the second transistor. The biasing analysis is similar to that of RC coupled Amplifier except that two Vbe drops are to be considered. ADVANTAGES OF DARLINGTON AMPLIFIER It uses very few components and can be readily formed from two adjacent transistors in an IC. It provides excellent Characteristics of high input impedence with low output impedence and high curren...

In the circuit use a IC AN7171 . Minimum requirment  voltage is 12 volt and maximum voltage is 15  volt . Power output 2 X 30 W with impedance 4 Ohm . Speaker match woofer speaker , and operate it on the small room. This circuit matches variety of input device such us mixer , equalizer , tone control , processor , galaxy , bass boost , giga bass , and etc. This circuit schematic below : AN7171 amplifier schematic Output speaker is stereo , output couple with ground and add commponent resistor 2,2 Ohm and capacitor 100 nF.

The 600W Audio Amplifier Circuit Diagram is based around {LM4702}manufactured by NATIONAL semiconductors&{MJ11029-MJ11028} by ON semiconductors It is a high fidelity audio power amplifier. Designed for demanding consumer and pro-audio applications. You can also use this circuit with AV receivers, Audiophile power amps, Pro Audio High voltage industrial applications etc Amplifier output power maybe scaled by changing the supply voltage and number of output devices. The circuit includes thermal shutdown circuitry that activates when the die temperature exceeds 150°c. CIRCUIT’s mute function, when activated, mutes the input drive signal and forces the amplifier output to a quiescent state.  Simple 600W Audio Amplifier Circuit Diagram Power: Maximum Output power @ 8ohms : 300watt Absolute max power supply voltage :±38V to ±40V Recommended power supply voltage :±30V to ±35V

Solid state relays are almost everywhere these days, but they are very expensive. So, your efforts to build their own salary. Especially since it’s only a few parts and circuit simple and straightforward. Solid state relay is not really at all relays. There are no “relay” is available only with electronics, connection works. It works well as a relay, you can use low voltage higher and better. “Relay” between 115/220V AC wires in place, although it was customary, the neutral conductor and leave unchanged phases and neutral. As long as no voltage (left in picture), the phototransistor TIL111 blocks of energy, and thus is not available. To ensure that the base TIL111 is fed to the transmitter (s) through the 1M resistor. This method prevents the base of transistor BC547B will be low and remains biased ‘on’. Collector is low and the gate (g) TIC106M thyristor, which is still in the country, “off”. 4-diode bridge rectifier circuit has no power apart from a small base and collector current B...

Here I tested a 600W 50Hz sine wave inverter circuit using push-pull topology instead of full-bridge topology. 2 PIC16F684's were used - one for SPWM and one for charging. 2 microcontrollers were used intentionally as the purpose was to test if I could use the microcontrollers together and use each of them for multitasking. 2 auxiliary transformers are used - one for powering the circuitry when running off mains and one for current sensing. Charging is done with 4 relays that are turned on/off according to input voltage and accordingly connect the input voltage to an appropriate transformer winding/tapping to keep output voltage relatively constant. Switching frequency is 16kHz. The sine table has 32 values. Here is the complete sine table: 0, 16, 32, 47, 62, 77, 91, 103, 115, 126, 136, 144, 151, 156, 160, 162, 163, 162, 160, 156, 151, 144, 136, 126, 115, 103, 91, 77, 62, 47, 32, 16, //65% 0, 17, 33, 49, 65, 80, 94, 107, 120, 131, 141, 149, 156, 162, 166, 168, 169, 168, 166, 162, 1...

Amplifier circuit is very suitable for use in subwoofer amplifier system based on IC SI1030G. Amplfier has 30W output with 8 ohm impedance. Supply voltage required minimum of 12 volts and a maximum of up to 22 volts DC. Component List : R1 = 100K R2 = 1R C1 = 2.2uF C2 = 100uF C3 = 47uF C4 = 100nF C5 = 10uF C6 = 47uF C7 = 100uF IC = SI1020GL , SI1030G

Simple and cheap, the circuit built based on well-known IC regulator LM317 with current booster of power transistor 2N3782. Don’t forget to add heatsink especially for power transistor 2N3782.

Useful for power lines control, Simple, transformer less circuitry. This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs to be detected. D3 illuminates when the line voltage is approaching 120V and will remain in the on state also at 240V supply. On the other hand, D6 will illuminate only when the line voltage is about 240V and will stay on because the latching action of Q1, Q2 and related components. C1, D1 and D2 provide a low dc voltage in the 4.5V - 6V range in order to allow proper operation of latch circuit and LEDs. 110 and 220V AC LED Voltage Indicator Circuit diagram: 110 and 220V AC LED Voltage Indicator Circuit Diagram Parts: R1__________470R 1/2W Resistor R2__________220K 1/4W Resistor R3,R7_______470R 1/4W Resistors R4__________1K 1/4W Resistor R5__________2K2 1/4W Resis...

The project I’m going to describe today it’s a sort of proof of concept that will demonstrate the possibility to remote control sensors and actuators (for example a couple of relays) via Telegram. Telegram is an instant messaging application, similar to the famous Whatsapp. Last June, the Telegram developers announced that a new set of APIs were available to develop bots. [ ]

Dynamometer Type Wattmeter This is also similar in design and principle to the dynamometer type ammeter and voltmeter. Pic 1 Construction: In the dynamometer type instrument is used as a wattmeter, the fixed coil, which is divided into two equal portions, the fixed coils are connected in series with the load and carry the circuit (or load) current, therefore it is also called as current coil. The moving coils is connected across the load and carries the current proportional to the voltage across the circuit. Therefore, it is known as pressure coil or potential coil. A high non-inductive resistance ‘R’ is connected in series with the moving coil to limit current through it. The magnetic field of the fixed and moving coils react on one another causing the moving coil to turn about its axis. The movement of the coil is controlled by hair springs also lead the current into and out of the moving element. Damping torque is provided by the air friction. Working: When the instrument is connect...

Since I really like using LiFePO4 AA and AAA batteries in some of my projects, I finally gave in and built a dedicated charger for them. Previously I used a lab power supply to mimic the constant current/constant voltage charging curve, which worked also fine. But after seeing Patrick Van Oosterwijck nifty LiFePO4wered/USB™, I thought it would be a bit more convenient to charge these batteries using USB. [ ]

Triangular Wave Oscillator Circuit Diagram . This design resulted from the need for a partial replacement of the well-known 8038 chip,  which is no longer in production and there fore hardly obtainable.  An existing design for driving an LVDT sensor (Linear Variable Differential Transformer),  where the 8038 was used as a variable sine  wave oscillator, had to be modernised. It may  have been possible to replace the 8038 with an  Exar 2206, except that this chip couldn’t be used  with the supply voltage used. For this reason we  looked for a replacement using standard components, which should always be available. In this circuit two opamps from a TL074 (IC1.A  and B) are used to generate a triangular wave,  which can be set to a wide range of frequencies using P1. The following differential amplifier using T1 and T2 is configured in such a way  that the triangular waveform is converted into  a reasonably looking sinusoidal wavefo...

I had previously used the Adafruit TFT display using my library (ported from the Adafruit Arduino library). I decided to optimize the library to improve drawing speed. The same display I use comes with a 4-wire resistive touch-screen as well. I decided to write a simple library for the touch-screen and give Protothreads a try. To incorporate all this, I thought it would be cool if I used these to make a simple game. Tic-tac-toe came to mind as a fun little demo. I'm sure everyone's familiar with the game so I won't explain the rules there. The touch-screen is simply two resistive sheets placed on top of each other on top of the TFT screen. When it is pressed down at a given place, the two sheets make contact and a voltage divider is formed. Using the IO's and the ADC, this voltage is read in the X and Y directions to register a touch. Here is a very good pictorial depiction of the resistive touch screen (taken from the Atmel AVR341 document ): So in order to read the to...

The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which can be used individuals to act as a deterrent against some animals. It should NOT be relied upon as a defence against aggressive dogs but it may help distract them or encourage them to go away and do not consider this as an electronic pest repeller. The ultrasonic dog repellant uses a standard 555 timer IC1 set up as an oscillator using a single RC network to give a 40 kHz square wave with equal mark/space ratio. This frequency is above the hearing threshold for humans but is known to be irritating frequency for dog and cats. Since the maximum current that a 555 timer can supply is 200mA an amplifier stage was required so a high-power H-bridge network was devised, formed by 4 transistors TR1 to TR4. A second timer IC2 forms a buffer amplifier that feeds one input of the H-bridge driver, with an inverted waveform to that of IC1 ou...

The 60 Hz inverter shown below is about as simple to make and as inexpensive as one could desire. Yes, it is capable of providing some very useful services. Operating from an automobile battery, it can supply 50 W for the operation of such devices as an ac-dc radio, electric shaver, fluorescent lamp, small soldering iron, 40 W incandescent lamp, recorder, or portable phonograph. Its essential ingredients are a filament transformer and two general-purpose germanium power transistors. Although this is a saturable-core oscillator, no separate feedback windings are employed. Rather, feedback is produced by cross-coupled connections in the manner of a multivibrator. At a full load, the efficiency is in the vicinity of 75 percent, and the output voltage is about 106 V. The "mild" pi-section filter despikes the output waveform and causes a trapezoid wave, rather than the usual square wave, to be available at the output. This makes the device more suitable for the operation of radios...

This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's output device. (E.g. MOC 3010/3020) If a relay is unavoidable, use one with a mains voltage coil and switch the coil using the optical isolator.C1 should be of the 'suppressor type'; made to be connected directly across the incoming Mains Supply. They are generally covered with the logos of several different Safety Standards Authorities. If you need more current, use a larger value capacitor; or put two in parallel; but be careful of what you are doing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2....

What i am making here is a USB lock with smartcard key. The idea is that a phonecard reader made with a PIC micro will be able to store a number of different phonecards into memory. Whenever one of these cards is inserted into the slot, it will activate a 4-ports USB On/Off switch. If the card is removed, the USB ports will be de-activated. [ ]

The family of Eddie Smith has auctioned off their late father's 1967 Ferrari 275 GTB/4*S N.A.R.T Spider, and generously donated all the proceeds to charity. The rare car (only 10 were ever made) was sold Saturday night at RM Auctions in Monterey, Calif., for $27.5 million. That price set a new world record for the most expensive road car of any kind sold at auction.  Smith took ownership of the Ferrari in 1968, and his son, Eddie Smith Jr., told the auction crowd that selling it was "a bittersweet moment." According to the Los Angeles Times, he advised its new owner to "Drive it, love it, enjoy it, and more importantly share it with others so they can see it." [Source] [Source  ] Trending topic: ferrari auctioned | Click to see more on msnNOW.com

Rotel SURROUND SOUND RECEIVER RSX-1057 Continuous Amplifier Power (five channels driven) 75 watts/ch (20-20k Hz, <0.05% THD, 8 ohms) Continuous Amplifier Power (two channels driven) 100 watts/ch (1kHz, <1.0% THD, 8 ohms, DIN) Power Requirements (AC) 120 volts, 60Hz (USA version) 230 volts, 50Hz (CE version) Rotel SURROUND SOUND RECEIVER  RSX-1056 Continuous Amplifier Power (five channels driven) 75 watts/ch (20-20k Hz, <0.05% THD, 8 ohms) Continuous Amplifier Power (two channels driven) 100 watts/ch (1kHz, <1.0% THD, 8 ohms, DIN) Power Requirements (AC) 115 volts, 60Hz (USA version) 230 volts, 50Hz (CE version) RSX1056 power schematic RSX1056 Power amplifier schematic and PWB RSX1057 Power schematic RSX1057 Power amplifer schematic and PWB

Here is a simple but inexpensive inverter for using a small soldering iron (25W, 35W, etc) In the absence of mains supply. It uses eight transistors and a few resistors and capacitors. Transistors Q1 and Q2 (each BC547) form an astable multivibrator that produces 50Hz signal. The complementary outputs from the collectors of transistors Q1 and Q2 are fed to pnp Darlington driver stages formed by transistor pairs Q3-Q5 and Q4-Q6 (utilising BC558 and BD140). The outputs from the drivers are fed to transistors Q7 and Q8 (each 2N3055) connected for push-pull operation.  Use suitable heat-sinks for transistors Q5 through Q8. A 230V AC primary to 12V-0-12V, 4.5A secondary transformer (T1) is used. Soldering Iron Inverter Circuit Diagram   The centre-tapped terminal of the secondary of the transformer is connected to the battery (12V, 7Ah), while the other two terminals of the secondary are connected to the collectors of power transistors T7 and T8, respectively. When you power the ci...

This project is an audio amplifier based on TDA2050 and LM1875. This is not an ordinary project, but an attempt to make a PCB that is suitable for TDA2050 and LM1875 and has all the necessary circuitry on board – power supply, speaker protection, delayed turn-on and fast turn-off. This is achieved using the convenient uPC1237 IC. TDA2050 and LM1875 are pin to pin compatible, the differences in their schematics are the values of a couple resistors and one capacitor. All this allows to make an universal circuit board, suitable for any of these two ICs. [ ]

This amplifier is the monophonic 270 watt Double barreled Amplifier. For the original article, I specified plus and minus 85 V dc power supply voltages. The voltage can be increased to about 93 V to obtain a power rating of 300 W. The amplifier can be built either as a stereophonic or a monoponic unit. My original amps were mono units because the heat sinks, transformer, and filter caps that I used were too large for a stereo amp. The circuit described on this page is a modification of the original Double Barreled Amplifier. The circuit has been simplified somewhat. The circuit board layout is smaller and much more compact. The driver transistors now mount on the circuit board instead of on external heat sinks. And the circuit has the feedforward compensation that I describe for the Low TIM Amplifier. If you build this amplifier, you must keep the wiring between the heat sinks and the circuit boards as short as possible if you don't want oscillation problems. When you test the circ...

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