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How to build a Simple Sensitive Optical Burglar Alarm Circuit Diagram ? This optical burglar alarm uses two 555 timer ICs. Both the ICs are wired as astable multivibrators. The first astable multivibrator built around IC1 produces low frequencies, while the second astable multivibrator built around IC2 produces audio frequencies. Simple Sensitive Optical Burglar Alarm Circuit Diagram General-purpose Darlington photo-transistor 2N5777 (T1) is used as the light sensor. To increase the sensitivity of the circuit, npn transistor BC547 (T2) is used. Place phototransistor T1 where light falls on it continuously. Phototransistor T1 receives light to provide base voltage to transistor T2 . As a result, transistor T2 conducts to keep reset pin 4 of IC1 at low level. This disables the first multivibrator (IC1) and hence the second multivibrator (IC2) also remains reset so the alarm (loudspeaker LS1) does not sound. When light falling on Darlington phototransistor T1 is obstructed, transistor ...

This is a simple electro meter circuit.This circuit will detect electrostatic charge from the any material such plastic,comb etc. It can measure up to 30 cm from the target material. To use this circuit first adjust R2 when the antenna near the material until Amp meter read 1 mA. Electro meter circuit Diagram

Hey all, some folks on the XP Embedded team have recorded some video demonstrations of various features of XP Embedded, including walkthroughs of some of the new XPE SP2 features.  Click here to check them out today!  I did the Device Update Agent (DUA) video, so please forgive me for being a little nervous.  I also had a really bad cold the day I recorded it and had to stop for some coughing fits, but the folks in the MSDN recording studio did a great job of editing it out  🙂  Here's a complete list of the videos that are available (not all of them are new): Accelerated Operating System Configuration Automated Dependency Checking and Build Process Building a Windows XP Embedded Device Device Update Agent for Windows XP Embedded Windows Embedded Application Development Windows XP Embedded – Basic Lab Windows XP Embedded Product Overview Windows XP Embedded with Service Pack 2 – Basic Windows XP Embedded with Service Pack 2 Technical Training: Embedded Enabling Features ...

SMPS U-Com expander MPEG DVD DSP Drive-IF circuit

This circuit will automatically switch on several mains-powered "slave" loads when a "master" load is turned on. For example, it will switch on the amplifier and CD player in a stereo system when the receiver is turned on. It works by sensing the current draw of the "master" device through a low value high wattage resistor using a comparator. The output of that comparator then switches on the "slave" relay. The circuit can be built into a power bar, extension cord or power center to provide a convenient set of "smart" outlets that switch on when the master appliance is powered (turn on the computer monitor and the computer, printer and other peripherals come on as well). Automatic Load Sensing Power Switch Circuit Diagram   Parts Part               Total Qty. Description C1, C3               2             ...

A very efficient 6V to 15V DC to DC converter using LM2585 is shown here. LM2585 is a monolithic integrated voltage converter IC that can be used in various applications like flyback converters, boost converters, forward converters, multiple output converters etc. The circuit requires minimum number of external components and the IC can source up to 3A output current. Circuit diagram : 6 to 15V DC to DC Converter Circuit Diagram Here the IC is wired as a boost converter where resistors R1 and R2 are used to set the output voltage .The junction of R1 and R2 is connected to the feedback pin of IC1. Capacitor C4 is the input filter while capacitor C1 the filter for output. Network comprising of resistor R1 and capacitor C2 is meant for frequency compensation. Inductor L1 stores the energy for acquiring boost conversion. Notes:      Assemble the circuit on a good quality PCB. LM2585 requires a heatsink. Output voltage is according to the equation Vout =( (R1/R2)+1) x 1....

This is a wireless microphone circuit which transmits the FM frequency and uses a coil on the printed circuit board itself. This transmitter has a good frequency stability, its sensitivity is excellent and audio consumption is about 30mA. The size of the PCI board is 25mm by 50mm.The power supply is made ​​by a 9V battery. and its range can be more than 100 meters.  FM Wireless Microphone with Coil PCI Circuit Diagram To improve the transfer transistor 2N2222 use in place of BC547.You have to remove the 4K7 resistor if you use a dynamic type microphone.

This circuit idea is certainly not new, but when it comes to making a trade-off 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 handy. If forced cooling is an afterthought and the available options are limited then perhaps there is no other  choice. At low currents a capacitive divider requires less space than a small,  short-circuit proof transformer. Circuit diagram : 12V Fan Directly on 230 V Circuit Diagram R1 and R2 are added to limit the inrush current into power supply capacitor C2 when switching on. Because the maximum rated operating voltage of resistors on hand is often not known, we choose to have two resistors for the current limit. The same is true for the discharge resistors R3 and R4  for C1. If the circuit is connected to a mains  plug then it is not allowed that a dangerous voltage remains on the plug, hence R3 and R4. Capacitor C1 determi...

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24v DC is a very popular voltage used in industrial settings. This hobby circuit below was designed to accept four different 24v DC alarm input signals, which are then used to drive a single low power beeper. The beeper is a magnetic type with its own oscillator/driver. The four diodes form an “OR” gate so any one of the four inputs will cause the beeper to make noise. A CMOS version of the popular 555 timer is used to strobe the beeper on and off at about 1Hz.   Copyright: Discover Circuits

Alcohol Gas Sensor MQ-3 is an alcohol sensor is suitable for detecting levels of alcohol directly, for example on our breath. Alcohol Sensor MQ-3 has high sensitivity and fast response time. Alcohol Sensor MQ-3 series drivers for alcohol Sensor MQ-3 is very simple, only need 1 piece of variable resistors. Output of Sensor MQ-3 alcohol in the form of an analog voltage that is proportional to the alcohol content is received. The necessary interface is quite simple, can use the ADC that can respond to voltage 0 volt - 3.3 volt saja.Nilai mounted resistors must be differentiated for various types of gas concentration. So need to be calibrated to 0.4 mg / L (about 200ppm) concentrations of alcohol in the air and on the output resistance of about 200K (100K to 470K) Alcohol Gas Sensor MQ-3 Featured Alcohol Gas Sensor MQ-3: Sensitivity to high alcohol and low on gasoline Fast response and high sensitivity Stable and durable 5VDC or AC voltage source Operating Temperature -10 70 degree C samap...

Crowbar circuits are so-called because their operation is the equivalent of dropping a crowbar (large steel digging implement) across the terminals. It is only ever used as a last resort, and can only be used where the attached circuit is properly fused or incorporates other protective measures. A crowbar circuit is potentially destructive - if the circuitry only has a minor fault, it will be a major fault by the time a crowbar has done its job. It is not uncommon for the crowbar circuit to be destroyed as well - the purpose is to protect the device(s) attached to the circuit - in this case, a loudspeaker. Description There's really nothing to it. A resistor / capacitor circuit isolates the trigger circuit from normal AC signals. Should there be enough DC to activate the DIAC trigger, the cap is discharged into the gate of the TRIAC, which instantly turns on ... hard. A TRIAC has two basic states, on and off. The in-between state exists, but is so fast that it can be ignored for a...

More and more electronic devices are portable and run off batteries. It is no surprise, then, that so many flat batteries find their way into the bin and often far too early. When a set of batteries can no longer run some device for example, a flashgun the cells are not necessarily completely discharged. If you put an apparently unserviceable AA-size cell into a radio-controlled clock with an LCD display it will run for months if not years.  Of course not every partially discharged cell can be put in a clock. The circuit presented here lets you squeeze the last Watt-second out of your batteries, providing a bright ‘night light’ - for free! The circuit features a TBA820M, a cheap audio power amplifier capable of operating from a very low supply voltage. Here it is connected as an astable multivibrator running at a frequency of around 13 kHz. Together with the two diodes and electrolytic capacitor this forms a DC-DC converter which can almost double the voltage from between four and ...

Used ICs: 24C08 – NOM8370-B-16NB or TDA9381C38ND – AN7522N – STV9302A – KA5Q0765(STR) SMPS [Split]

This is a 100 Watt Inverter Circuit Diagram with Veroboard Print (LOW COST). This 100 watt Inverter Circuit use Minimum number of Components.I think it is quit difficult to make a decent one like this with further less components.Here we use {CD 4047 IC} for generating the 100 Hz pulses and four {2N3055} Transistor for driving the load.The IC1 {CD 4047} wired as an Astable  multi vibrator produces two 180 degree out of phase 100 Hz pulse train.These pulse train are preamplifier by the two TIP122 100 Watt Inverter Circuit Diagram Transistor.The output of the TIP122 Transistor are amplified by fout 2N3055 Transistor {Two transistor for each of half cycle} to drive the inverter transformer.The 220 AC be available at a secondary of the transformer.Nothing complex just the elementary inverter principle and the circuit great for small load like a few savers or fans.This is LOW COST inverter only 7 $. Info     12v Car Battery can be use for this Inverter Circuit.  ...

Description  Circuit showing a morning alarm.Here we have used a switching transistor.When the sun rise up ldr is low resistance so the ldr is conduct and a positive volt coming to the base of the Q1 there for the transistor will switch.This time  the buzzer is ON . Adjust the preset control the intensity of light.Manually cut off the power.Are you interested please comment and join this site Component Required                 Resistor  4.7k preset  , LDR                 Transistor   BC 548                 Buzzer

This circuit shows how far integration can be taken: IC1, a Type HT82207 from Holtek does virtually everything. Only a (small) loudspeaker and the necessary selectors need to be added. The standard 18-pin Type HT82207 is an integrated sound generator, producing sounds typical of the Old West. The various sounds are selected by S1–S6 as listed below. In the quiescent state, the circuit draws a current not exceeding 1 µA. S1 – bugle S2 – neighing S3 – sound of hooves S4 – pistol shot S5 – crack of a rifle S6 – cannon fire Circuit diagram:

Low-Voltage Remote Mains Switch Circuit diagram. This circuit allows a 240V mains appliance to be controlled remotely via low-voltage cabling and a pushbutton switch. The mains appliance (in this case, a light bulb) is switched with a suitably-rated relay. All of the electronics is housed in an ABS box located in proximity to the appliance. The pushbutton switch and plugpack are located remotely and can be wired up with 3-core alarm cable or similar. Cable lengths of 20m or more are feasible with this arrangement. When the switch (S1) is pressed, the input (pin 8) of IC1c is briefly pulled low via the 10mF capacitor, which is initially discharged. Low-Voltage Remote Mains Switch Circuit diagram Low-Voltage Remote Mains Switch Circuit Diagram The output (pin 10) immediately goes high and this is inverted and fed back to the second input (pin 9) via another gate in the quad NAND package (IC1d). In conjunction with the 1MW resistor and 470nF capacitor, IC1d eliminates the effects of conta...

In this circuit, the 7815 regulatates the positive supply, and the 7915 regulates the negative supply. The transformer should have a primary rating of 240/220 volts for europe, or 120 volts for North America. The centre tapped secondary coil should be rated about 18 volts at 1 amp or higher, allowing for losses in the regulator. An application for this type of circuit would be for a small regulated bench power supply.   Dual Regulated Power Supply Circuit Diagram

If you are tired of connecting the same I/O devices every time you prototype a new project then this board could save you a lot of time. All the necessary pins of the devices on the board are accessible through headers that allows easy connection of the board to a breadboard circuit or other development boards (Arduino, etc) using jumper wires. [ ]

This digital volume control has no pot to wear out and introduces almost no noise in the circuit. Instead, the volume is controlled by pressing UP and DOWN buttons. This simple circuit would be a great touch to any home audio project. Sooper Digital Volume Control Schematic Parts: Part Total Qty. Description C1 1 0.1uf Ceramic Disc Capacitor U1 1 DS1669 Digital Pot IC (See Notes) S1, S2 2 Momentary Push Button Switch MISC 1 Board, Wire, Socket For U1 Notes: 1. U1 is available from Dallas Semiconductor. 2. S1 turns the volume up, S2 turns it down. 3. The input signal should not fall below -0.2 volts. 4. Using a dual polariity power supply (+-5V works fine) will cure most clipping problems. You will have to check the data sheet for the correct pins to connect your voltages.

I got myself some UV-curable solder mask for my PCB workshop, and as soon as i got it, i discovered that my UV artwork transfer box is totally incapable to activate the UV paint and cure it. I began searching the net for powerful UV lamps, and then it hit me: Some months ago i uploaded a theory regarding the Cold and Hot cathode discharge lamps. During my research for these lamps i found out that they can provide directly visible light (lamps without internal coating), or they produce UV radiation. The lamps that produce UV radiation have an extra coating on their internal surface which glows when excited by the UV rays, thus producing light! [ ]

My new home theatre receiver was getting rather hot in the close confines of its cabinet, with the temperature reaching over 40°C after only about 30 minutes of use. To help lower the temperature, I decided to install a fan in the cabinet. A 75mm hole was cut in the shelf under the receiver, and a 12V fan salvaged from an old computer power supply was mounted underneath. The fan was powered from a 12V DC plugpack.  This did the job, keeping the temperature below 30°C even after prolonged use on a warm day. However, the fan was annoyingly loud when running at full speed. To reduce the noise level substantially, I built this fan speed controller with temperature feedback. The circuit was culled from variety of ideas found on various sites on the internet, with the final circuit designed from what was in the "junk box". Air temperature in the cabinet is sensed via an LM335 (TS1). Circuit diagram: Junk-box Fan Speed Controller Circuit Diagram It is glued to a piece of aluminium a...

Description. Here is a simple circuit in which an LED will continue flashing as long as the voltage of the battery to be monitored is above the set level.The transistors Q1 and Q2 are wired as a complementary astable multivibrator.The circuit can operate from a voltage range from 6V to 12V. The voltage level at which LED has to stop flashing can be set by adjusting the preset R4.When the battery voltage reaches the threshold the flashing frequency decreases and when the voltage goes below the threshold the LED becomes OFF.The diode D1 is used to compensate the changes in the base emitter voltage of Q1 due to temperature changes. Circuit diagram with Parts list. Notes. Assemble the circuit on a general purpose PCB. Batteries from 6V to 12V can be monitored by this circuit. The diode D1 must be a Schottky diode.

Problems can arise with USB hubs that are powered from a PC when gadgets plugged into them draw too much current. This is often the case with devices fitted with USB cables that are too long or too thin, causing voltage drop. There’s no need to scrap your old USB hub, however, if you upgrade it using this little circuit and an external power supply. Just cut the 5-V power wire of the USB cable inside the hub and solder a diode (D1) in the pass-through direction. Now connect the 5 V wire from the external power supply to the cathode of this diode. D1 prevents any current from the power supply from flowing back into the PC.  USB Hub Circuit Diagram

35Watts sub-woofer schematic using IC TDA7265

Tunable bandpass filters variable resistors One of the difficulties in the design of higher-order tunable bandpass filters is achieving correct tracking of the variable resistors in the RC networks. The use of switched capacitor networks can obviate that difficulty, as is shown in this filter. The filter can be divided roughly into two stages: an oscillator that controls the electronic switches arid the four phase-shift networks that provide the filtering proper. The oscillator, based on a 555, generates a pulsating signal whose frequency is adjustable over a wide range: the duty factor varies from 1:10 to 100:1. Electronic switches ESI through ES4 form the variable resistors whose value is dependent on the frequency of the digital signal. The operation of these switches is fairly simple. When they are closed, their resistance is about 60 ; when they are open, it is virtually infinitely high. a switch is closed for, say, 25% of the time, its average resistance is therefore 240 . `Varyi...

Description. W ith this compact FM adaptor circuit plugged into the audio out of your cassete player or i Pod out put,you can listen your favorite music on your car stereo.This circuit is very useful if your car stereo doesnot have an auxillary in socket.The circuit is nothing buy  an short range  FM transimitter. The FM transmitter circuit is based on low power NPN transistor 2N2222.The tank circuit consisting of L1 & C1 producess the necessary oscillations at the collector of Q1.The capacitance C4 , resistance R3 & R4  performs the function of mixing the stereo out put from theaudio player or i-Pod.The emitter resistance R2 provides sufficient stability to the circuit.It also limits the collector current to increse the battery life. Circuit diagram with Parts list. Notes. Use a 28SWG , 10 cm insulated copper wire as antenna. For L1.make 8 turns of 20 SWG insulated copper wire on a 5mm dia plastic former. Power the circuit from a 3V battery. Assemble the circ...

Having been affected by earth fault accidents,  the author put together this little circuit. It  consist of just three elements: the neon with its  original resistor for example, salvaged from  the switch on an AC power bar and a small  capacitor (class Y) salvaged from the electronics of a low-consumption lamp. A larger capacitance makes the neon glow brighter. All this  for no money at all. The neon lights only when there is an efficient Earth present. This works  well at the author’s home, with Live or Neutral either way round. In the Elektor laboratory based in The Netherlands, some concerns  were expressed as described in the June 2011  issue [1], as the circuit was sensitive to the relative positions of the Live and Neutral. So the  Earth fault detector can also be used as a Phase  detector, but probably in Belgium only. . The whole thing can easily be incorporated into a power socket; the author used a small transparent cove...

The key to using a soundcard successfully in digital signal processing or digital radio applications lies principally in the characteristics of the soundcard itself. This applies in particular to SDR (software defi ned radio) programs that turn your PC into a top-class AM/SSB/CW receiver, assuming your soundcard cooperates. If you want to experiment with SDR and avoid a lot of frustration, it is worth checking fi rst whether the PC soundcard you plan to use is suitable. There are three essential elements to success: the soundcard must have a stereo line-level input; the card must be equipped with an input anti-aliasing filter; and the sample rate must be at least 48 kHz and the card must be able to cope with signals up to 24 kHz. Many laptops have only a mono microphone input, sometimes also rather limited in bandwidth. In this case it may be possible to use an external USB soundcard. Most desktop PCs these days have an internal integrated soundcard, although some of these do not feature...

This is a small switching power supply, a Schmitt trigger oscillator is used to drive a switching transistor that supplies current to a small inductor. Energy is stored in the inductor while the transistor is on, and released into the load circuit when the transistor switches off. Circuit diagram : 2W Switching Power Supply Circuit Diagram The output voltage is dependent on the load resistance and is limited by a zener diode that stops the oscillator when the voltage reaches about 14 volts. Higher or lower voltages can be obtained by adjusting the voltage divider that feeds the zener diode. The efficiency is about 80% using a high Q inductor.

Having anything that is “cute” does seem to work these days, and considering how many of us carry a fair number of gadgets, it can be quite a task trying to make sure that all of them are fully juiced at the beginning of each day. Having said that, having a car charger in your ride is not too bad an idea after all, since you can never quite tell just when you might need to fall upon some backup power on the way to your meeting, with your smartphone running on empty. Why not get something cute while you are at it The $19.99 HoneyDru USB Car Power Adapter will certainly not disappoint, where this small, bee-shaped car power adapter will come with light-up eyes and wings for added “coolness” effect, especially during the evenings. Good thing nobody should be allergic to this bee-like USB car power adapter, as it does not sting at all, and the only thing it does well would be to power up those thirsty batteries in your well used gadgets. The HoneyDru USB Car Power Adapter would be plugged ...

Circuit Diagram Two bands amplifier with bass alc surround Datasheet for TDA7468: Download

This project includes a number of improvements over my older Temperature Controlled NICD Charger circuit. This circuit runs on 12VDC, allowing it to be used in a car or from a 12V solar power system. Additionally, a current sensor LED verifies that the cells are receiving charging current. Note that the current sensor circuitry is not shown in the circuit board photo above, it was added to the side of the main board via a small perfboard. 12V, 4-AA Cell Differential Temperature Charger Circuit diagram The current is adjustable in three steps from 100 to 300mA, allowing fast charging of AA, AAA or other small cells. Battery packs from 1 to 6 cells can be charged with this circuit. NiMH and older NiCD cells are supported. The circuit is protected from reverse input voltage and reversed cells. Connections: 12VDC (nominal) power input Connections for the Battery Under Charge Controls: Power On/Off switch Charge Start switch 3 step Charge Current Select jumper Calibrate/[Latch] mode jumper ...

This simple circuit can be used to charge batteries from a solar cell array. The circuit consists of an oscillator, a DC-DC step-up or ‘boost’ converter and a regulator that pro-vides regulation of the output voltage.The oscillator is built around a hex Schmitt trigger inverter IC, the 40106B, one resistor, R1, inserted between the input and the output of one of the gates in the 40106 to supply charge to C3. Depending on the values of resistor R1 and capacitor C3 you’re using in the circuit, the oscillator will operate at different frequencies, but a frequency below 100 kHz is recommended. By consequence, the oscillator frequency should not exceed the maximum ripple frequency of capacitor C2 connected on the output. C2 should be an electrolytic capacitor with a DC working voltage larger than the desired output voltage. Besides, it should have a low ESR (equivalent series resistance). Solar Cell Array Charger with Regulator Circuit Diagram : IC1A is used as a buffer, ensuring that t...

The controller uses one or more ordinary silicon diodes as a sensor, and uses a cheap opamp as the amplifier. I designed this circuit to use 12V computer fans, as these are now very easy to get cheaply. These fans typically draw about 200mA when running, so a small power transistor will be fine as the switch. I used a BD140 (1A, 6.5W), but almost anything you have to hand will work just as well. Thermal Fan Controller By IC 741 Circuit diagram:   Thermal Fan Controller Circuit Diagram Source: ESP

Description  This multi-tone siren is useful for burglar alarms, reverse horns, etc. It produces five different audio tones and is much more ear-catching than a single-tone siren. The circuit is built around popular CMOS oscillator-cum-divider IC 4060 and small audio amplifier LM386. IC 4060 is used as the mult-itone generator. A 100µH inductor is used at the input of IC 4060. So it oscillates within the range of about 5MHz RF. IC 4060 itself divides RF signals into AF and ultrasonic ranges. Audio signals of different frequencies are available at pins 1, 2, 3, 13 and 15 of IC 4060 (IC1). Circuit Diagram: These multi-frequency signals are mixed and fed to the audio amplifier built around IC LM386. The output of IC2 is fed to the speaker through capacitor C9. If you want louder sound, use power amplifier TBA810 or TDA1010. Only five outputs of IC1 are used here as the other five outputs (pins 4 through 7 and 14) produce ultrasonic signals, which are not audible. Assemble the circuit...

Here is a solar powered Flasher to scare away the nocturnal animals like bats and cats from the farm yard or premises of the house. The brilliant multicolored flashes confuse these animals and they avoid the hostile situation. It is fully automatic, turns on in the evening and turns off in the morning. The circuit has an LDR controlled oscillator built around the Binary counter IC CD 4060.The functioning of the IC is controlled through its reset pin 12. During day time, LDR conducts and keeps the reset pin of IC high so that it remains dormant. During night, LDR cease to conduct and the reset pin will be grounded through VR1. This triggers the IC and it stats oscillating using the components C1 and VR2. Output pins 7, 5 and 4 are used to power the LEDs strings. VR1 adjusts the sensitivity of LDR and VR2, the flashing rate of LEDs. High bright Red, Blue and White LEDs are used in the circuit to give brilliant flashes. Red LEDs flash very fast, followed by blue and then White. White LEDs...