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One tool that I’ve been missing at my lab at home is function generator. They tend to be a bit expensive, so I haven’t bought one. I thought this might be a good opportunity to try and make one myself. I found a pretty common DDS (direct digital synthesis) chip, called AD9833. Then just strap a USB-enabled AVR micro there and maybe some analog electronics. This board doesn’t do any of the special analog magic to allow for variable amplitude or offset for the signal. The output is fixed to 0-4v. I’m planning to make another completely analog board for adjusting amplitude and offset.

This is a Simple 0.5V Negative Supply Circuit Diagram . This simple circuit consists of two LEDs and a photo diode. It generates a negative voltage with a current level of a couple milliamps. It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output. Note: This circuits is not particularly efficient.   Simple 0.5V Negative Supply Circuit Diagram

On this schematic need , Power Supply with voltage : 15 -35 V, if voltage is under 15 volt so the sound will be weak. and is higher 35V will cause the IC hot and fast risk. Output power 14 Watt with impedance 10 Ohms. See circuit diagram  below :

Description: This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It's designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro switches - foil tape - and PIRs. But it can be Easily Modified to accept normally-open triggering devices - such as pressure mats. Circuit Diagram   Notes:   It's easy to use. First check that the building is secure and that the green LED is lit. Then move SW1 to the "set" position. The red LED will light. You now have about 30 seconds to leave the building. When you return and open the door - the Buzzer will sound. You then have about 30 seconds to move SW1 to the "off" position. If you fail to do so - the relay will energize and the Siren will sound. While at least one of the switches in the normally-closed loop remains open - the Siren will continue to sound. However, about 15-minutes aft

Circuit Diagram: 50W Power Amplifier Part list: Part list

This is a circuit of an alarm residential sectors 5, or 5 areas that are monitored separately, it also has a panic button, timing system, is powered by the network jointly by battery v. 12. It is very simple and uses only three integrated circuits and transistors.  Simple Alarm Residential 5 sectors Circuit Diagram

This is the tone booster schematic diagram which is published on Everyday Electronics, September 1978 edition. The peaks of frequencies is at 5000 Hz for a “cleaner and more penetrating” sound. The Q1 type is ztx384, while the Q2 is BC415p.  Simple Tone Booster Schematic Diagram

High Current Step-Up Converter Using MAX641 integrated circuit, manufactured by Maxim IC, can be designed a very simple step-up converter using few electronic components. This step-up high voltage converter electronic projects allows a maximum output current up to 1A. High Current Step-Up Converter Circuit Diagram Low battery voltage detector input compare LB1 with internal reference of 1.31 V. LBO output goes in low state when the voltage at pin 1 falls below 1.31 V. The threshold voltage for "low battery", is determined by voltage divider R1-R2. LED D1 illuminates the LBO output when the input voltage falls below 2.62 V. Input voltage must remain below 5 V. The maximum effectiveness is 80% conversion.

A fast electronic fuse designed to operate on 230V AC with an adjustable trip current.     Fast Electronic Fuse Circuit Diagram :    Note : When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is open, the range is approximately 300-650 mA, and 0.8-2A when it is closed. The key variable in the operation of the fuse is the voltage drop across the power resistor(s) which are connected in series with the load. This voltage drop is directly proportional to the current the load draws. When this current is low, the voltage across the resistors is also small and cannot trigger T1. At the same time the gate of T2 is fed from a little power supply built around a negative voltage regulator. T2 is conducting and the load is on. If the current through the load then gets too high, so that the voltage created across the resistor(s) can trigger the gate of T1 through the 330R resistor and

Circuit Skema Rangkaian -  High Power Amplifier has great advantages are 5000W ultra-light, high-power audio amplifier , without switching-mode power supply. This ambit is of an 2 x 2,500W RMS Stereo amplifier , super - light and after switching-mode ability supply. The ambit aloof shows a channel, and the ability accumulation that it assists to the two channels. The audio ambit should be duplicated, but the ability accumulation assists to the two channels after problems. Circuit Skema Rangkaian Power Amplifier 5000W A adapted affliction should be destined to the careful agent of the audio line, that should be of audio-high-quality, of the blazon acclimated in microphone pre amps ascribe line. The accomplished accumulation (2 channels) of 5,000W RMS it should not counterbalance added than 32 lbs, already central of an adapted brownish box. WARNING: This ambit is alone for abecedarian use. It contains not-isolated genitalia of the electric AC net and it can be actual dangerous. The

This is a Simple Power Pulse Using by LM350 and NE555 Circuit Diagram . This circuit can use to drive lamp,power LED,DC motor etc. Adjust R5 for output amplitude.Adjust R1 for output power . Power Pulse Circuit Diagram The LM350 is adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 3A over a 1.2V to 33V output range.This circuit requires 5-15V power supply.

The BA3822LS BA3822FS BA3823LS and BA3824LS are monolithic, five-point stereo graphic equalizer ICs. Each IC has two channels, and the five center frequencies for each channel are independently set using external capaci- tors. These ICs feature a wide operating power supply voltage range (VCC = 3. 5V to 14V), and are available in compact 24-pin SZI visit page. P and SSOP packages, depending on the type. This makes them an ideal choice for home stereo systems, Radio cassette players, and car stereos. The difference between the ICs is the amount of boost and cut control. Choose according to the requirements of your application By ROHM Co. Ltd. via next.gr Am Radio / Fm If Stereo System Ic

Presented here is a solution for switching off outdoor lamps even when you are not at home. The lamp turns on in the evening and turns off in the morning so that there is no need for manually switching it on/off. The circuit is directly powered from AC mains and can be enclosed in a plug-in type adaptor box. It can drive a bulb, CFL, tubelight, LED lamp, etc up to 200W. Author’s prototype is shown in Fig. 1. Circuit and working Fig. 1: Author’s prototype The circuit uses a transformer-less power supply to generate low-volt DC. As capacitors C1 and C2 are connected in AC lines, these should be X-rated capacitors. This minimises space and makes the unit light-weight. Unlike an ordinary capacitive power supply, a more efficient power supply design is used for spike-free operation. Phase (L) and neutral (N) lines have identical circuits so reversal in polarity while plugging will not affect the circuit. 105K (1µF) 400V AC capacitors are used that can drop 230V AC to low-level AC. Resistors

If users don't update their Windows Phones to 7.5, they won't be able to access Marketplace. (Credit: Josh Miller/CNET)    Anyone with a Windows Phone that hasn't been upgraded to version 7.5 won't be able to use Microsoft's Marketplace app store as of today. Microsoft announced today that in order to download, buy, update, or review apps in Marketplace, users have to be running Windows Phone 7.5. This change is required for both the phone and web Marketplace storefronts. "Most phones are already running Windows Phone 7.5, which was released last fall, and so most of you won't notice anything different about how the Marketplace works," Microsoft's director of program management, Mazhar Mohammed, said in a blog post today. "However, if your phone has an earlier version of our software installed, you'll soon start seeing an error message when you try to download a new app, or update one you already own."

Circuit Diagram Description This circuit is a Digital Radar Speedometer. It allows us to evaluate the speed of any object moving, especially cars and other vehicles. The speed is calculated in kilometers per hour (KPH). Its display has three digits. This radar works with the laser reflexion. It sends laser radiation to the object and this object reflects the laser radiation to the radar. To evaluate the speed of a vehicle, we must be in front of it. In other words, the vehicle must come in our direction. The front of the radar must point the front of the vehicle. The radar has the shape of a pistol. In this radar, it has a laser LED and a laser diode. Both have a lens. The laser LED can send a spot of light to a distance of 90 m (295 ft). It's very important that the distance range of the laser LED is 90 m, if not, the speed will not be calculated properly. The laser diode, which receives the light signal by the laser LED, must be able to detect the light which is same color as tha

Description The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of the bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a zener regulated supply provided on the circuit. Each tone response is defined by a single capacitor chosen to give the desired characteristic. Circuit Diagram Features Wide supply voltage range, 9V to 16V Large volume control range, 75 dB typical Tone control, ±15 dB typical Channel separation, 75 dB typical Low distortion, 0.06% typical for an input level of 0.3 Vrms High signal to noise, 80 dB typical for an input level of 0.3 Vrms Few external components required . Note: Vcc can be anything between 9V to 16V and the output capacitors are 10

This simple electronic circuit project has helped me out on many occasions. It is able to check transistors, in the circuit, down to 40 ohms across the collector-base or base-emitter junctions. It can also check the output power transistors on amplifier circuits. Transistor Tester Circuit Diagram: Circuit operation is as follows.  The 555 timer ( IC1 ) is set up as a 12hz multi vibrator. The output on pin 3 drives the 4027 flip-flop (IC2). This flip-flop divides the input frequency by two and delivers complementary voltage outputs to pin 15 and 14. The outputs are connected to LED1 and LED2 through the current limiting resistor R3. The LED's are arranged so that when the polarity across the circuit is one way only one LED will light and when the polarity reverses the other LED will light, therefore when no transistor is connected to the tester the LED's will alternately flash. The IC2 outputs are also connected to resistors R4 and R5 with the junction of these two resistors co

This digital thermometer circuit diagram uses a common 1N4148 diode as the temperature sensor. The temperature coefficient of the diode, -2 mV / 0C is exploited for this application to create an accurate electronic thermometer. To display the measured temperature, a digital multimeter is used and so we can measure temperature values from -9.990C up to +99.90C.   Calibration of the digital thermometer To set the minimum level (00C), place the diode in a glass of water filled with crushed ice (check the temperature first with a normal thermometer) wait until the thermometer shows zero degrees centigrade. Set P1 so that the digital voltmeter will display 000 when the diode senses zero degree centigade. To set the maximum level (1000C), place the diode sensor into a boiling water and adjust P2 so that the digital meter exactly displays 99.9. source [link] 

UV (ultra-violet) LEDs can produce eye-catching effects when their light is allowed to interfere with certain colours, particularly with reflected light under near-dark conditions. Also try shining some UV light on a diamond. Circuit diagram :  UV Torch Light Circuit Diagram Most UV LEDs require about 3.6 V (the ‘blue’ diode voltage) to light. Here, a MAX761 step-up switching IC is used to provide constant current to bias the UV diode. The IC employs PWM in high-cur-rent mode and automatically changes to PFM mode in low or medium power mode to save (battery) power. To allow it to be used with two AA cells, the MAX761 is configured in bootstrapped mode with voltage-adjustable feedback. Up to four cells may be used to power the circuit but they may add more weight than you would like for a torchlight. To prolong the switch life, R1 is connected to the IC’s SHDN (shutdown) pin. Less than 50 nA will be measured in shutdown mode. Electrolytic capacitor C1 is used to decouple the circu

Networking Basic for PLC Engineer   In the world of computers, networking id the theory of connecting 2 or more computing devices together for the purpose of sharing important data. Networks are built with mix of hardware & software. Basically Networks are categories into      Peer to Peer Networks      Client Server Networks IEEE has developed different communication standards which are summarized in following table. IEEE 802 Standards   Network Cabling   Cabling is medium through which information usually moves from one network device to another. There are several types of cables used in networks. Some Guidelines for Installing Cables   When running cable , it is best to follow few basic rules:   Always use more cable than you need. Leave plenty of slack Test every part of a network as you install it. Even if it is a brand new, it may have problems that will be difficult to isolate later.   Stay at least 3 feet away from fluorescent light boxes and other sources of electrical i

This simple Sound-Activated Lamp circuit shown int the schematic diagram actives the switch using sound. We can use this circuit for various applications, such as automatic (sound-controlled) disco light or car’s LED light show.  The Q1 amplify the audio from mic. The R1 is used to adjust the peak of signal to greater than about 0.7 volts, act as sensitivity adjuster. A certain level, the signal coming from microphone, after amplification by Q1, will trigger the SCR and light lamp I1. If we change the lamp with a relay, then we can get a sound-activated relay/switch, which can be used to control more powerful / high wattage high voltage lamps. If we use a relay, place a 1N4007 diode in parallel with the relay coil to prevent the back-emf from  relay coil destroying the SCR.  Sound-Activated Lamp Circuit Diagram

OVER LIGHT DETECTOR Here i am going to Introduce you an Excess light Detector or sensor circuit. The sensing component used in this circuit is LDR (Light Dependent Resistor). LDRs are sensitive, inexpensive and readily available device. They posses good power and voltage handling capacity similar to an ordinary resistor. CIRCUIT DIAGRAM OF OVER LIGHT DETECTOR Components required to wire up this circuit 1. LDR 2. R - 1K 3. SCR 4. Buzzer 5. 5V BATTERY WORKING PRINCIPLE OF OVER LIGHT DETECTOR The LDR is a variable resistor whose resistance decreases with increase in light intensity. When the light falling on an LDR has normal intensity, its Resistance is large enough and the voltage across R is insufficient to trigger the SCR. However, when light falling on LDR is of large intensity, the Resistance of LDR falls and voltage drop across R becames large enough to trigger the SCR. Consequently the buzzer sounds the alarm. It may be noted that if the strong light disappears the buzzer continu

CIRCUIT DIAGRAM OF OP AMP BASED MONOSTABLE MULTIVIBRATOR (741 IC) MONOSTABLE MULTIVIBRATOR USING OP AMP 741 Monostable multivibrator is also called as One Shot Multivibrator. It has a Stable State and a Quasi-Stable State. The circuit remains in stable state until a triggering signal is applied to its input. After getting the triggering signal the output transit from stable to Quasi-stable state and return back after a time period. So a Single Pulse is generated for single Trigger. Consider the instant at which the output Vo=+Vsat. At that time diode D1 damps the Capacitor voltage, Vc at 0.7V. Feedback voltage is +βVsat at Non-Inverting terminal. When the negative trigger is applied, the potential at Non-Inverting terminal becomes less than 0.7v the output switches to -Vsat, which makes the diode more negative than -βVsat. Comparator switches back to +Vsat. The Capacitor C starts charging to +Vsat through R until Vc reaches 0.7v and C becomes damped to 0.7v. The pulse width is given by

Description  This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on feeding any appliance connected to SK1. Input audio signal is boosted and squared by IC2A & IC2B and monitored by LED D4. When D4 illuminates, albeit for a very short peak, IC3 is reset and restarts its counting. Pin 2 of IC3 remains in the low state, the two transistors are on and the relay operates. When, after a 15 minutes delay, no signal appeared at the input, IC3 ends its counting and pin 2 goes high. Q1 & Q2 stop conducting and the relay switches-off. The device is thus completely off as also are the appliances connected to SK1. C5 & R9 reset IC3 at power-on. P2 allows switch-off at any moment.  Circuit Diagram  Parts: R1,R8___________1K 1/4W Resistors R2,R3___________4K7 1/4W Resistors R4_____________22K 1/4W Resistor R5______________4M7 1/4W Resistor R6,R9__________10K 1/4W Resist

Digital Step-Km Counter Circuit Diagram. This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit) shows hundreds meters and its dot illuminates after every 50 meters of walking. A beeper (excusable), signals each count unit, occurring every two steps. A normal step was calculated to span around 78 centimeters, thus the LED signaling 50 meters illuminates after 64 steps (or 32 operations of the mercury switch), the display indicates 100 meters after 128 steps and so on. For low battery consumption the display illuminates only on request, pushing on P2. Accidental reset of the counters is avoided because to reset the circuit both push buttons must be operated together. Obviously, this is not a preci

This DC adaptor provides a regulated 9V source for operating a transceiver in the car .The IC LM317 is mpounting tab is electrically connected to its output pin. so take this into account tour version of the adapter. The LM317T regulator dissipates 2 or 3 Watt in this circuit , so mount it on a 1- x -2 inch piece of 1/8 inch thick alumunium heatsink. Dont forget to give heatsink on the IC LM317.

Definition of power amplifier A transistor amplifier which raises the power level of the signals that have audio frequency range is known as transistor power amplifier. In general the last stage of multistage amplifier is the power stage. A power amplifier differs from the voltage amplifier. A transistor that is suitable for power amplification is generally called as power transistor. Classification of Power Amplifier The power amplifiers can be classified in the following ways. 1.        According to the usage of Frequency Signals: (i)                   Audio frequency power amplifiers. (ii)                 Radio frequency power amplifiers. (iii)               Video frequency power amplifiers. 2.        According to the period of Conduction: (i)                   Class A Power Amplifiers: The period of conduction is for total 360 o (full cycle). (ii)                 Class B Power Amplifiers: The period of conduction is for 180 o (half cycle). (iii)               Class AB Power Ampli