Friday, December 27, 2013

Flyback Converter Circuit Diagram

A low-current fly-back converter is used here to generate ±15 volts at 20 mA from a +5 volt regulated line. The reference generator in the SG1524 is unused with the input voltage providing the reference. Current limiting in a fly-back converter is difficult and is accomplished here by sensing current in the primary line and resetting a soft-start circuit.

Flyback Converter Circuit Diagram

Flyback Converter Circuit Diagram

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Wednesday, December 25, 2013

If you desire the personal touch then skins

Look for special discounts and credit offers such as "no payments for 90 days for purchases over a certain dollar amount." These offers enable you to buy multiple items and make payments later without paying high credit card interest. Its a great way to do your holiday shopping from your computer while avoiding the crowded stores. Browse your favorite shopping mall online today to see what latest cell phone accessories are available to fit your budget.The popularity the new smart phones, many of which are multi-functional mobile devices are creating a wave of useful cell phone accessories. As more and more users rely heavily upon these devices items like cell phone chargers, cell phone cases, smart cell phone applications and more are breaking into the marketplace rapidly.Users now demand more flexibility with their devices and even more options with respect to various accessories that are used to personalize their smart phones. An emergence of custom made cell phone cases, multi-device mobile charging units and multi-faceted smart phone applications are emerging for every type of cell phone on the market.
If you desire the personal touch then skins, charms and faceplates will allow you to express your style. They turn the subdued or plain phone into a work of art.
Belt Clips and Vibrating Belt Clips - keeps your phone conveniently in place and lessens the chance of dropping or misplacing your investment.
The mobile communication products, the goal is to identify and introduce innovative products, very attractive and substantial benefits. For example, cell phone interceptor allows to control the traffic in one direction to provide much-needed peace of mind. Simply put, it filtered out the clutter. When the phone is located in mobile interceptor place, it sends a signal to the mobile phone operating at the same frequency, interference success.
Mobile phone interceptor can also be used as a means of combating terrorism. Within the communication range of business areas, from preventive measures to curb organized crime and assassin for remote activation of explosives.The problem has to eat sugar metabolism, it does not just burn.
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Monday, December 23, 2013

DC 12V Car Battery Charger

The circuit has been designed to produce a battery charger for automobiles that are using 12V batteries only. BTY79 is a 10A Silicon controlled rectifier with an operational temperature range from 0ºC to 125ºC. C106D is a 4A sensitive gate Silicon controlled rectifier that functions as reverse blocking thyristors designed for high volume consumer applications such as light, speed control, temperature, process and remote control, and warning systems where reliability of operation is important.

Circuit Diagram:


DC 12V - Car Battery Charger Circuit Diagram
DC 12V - Car Battery Charger Circuit Diagram

The typical car battery chargers have simple designs that produce a few amperes during its operation while charging the battery continuously. In the event that the charger is not turned OFF, overcharging will occur with due to evaporation which looses electrolyte and might cause damage to its elements. With the design of this circuit, this type of problem can be avoided by monitoring the condition of charging of the battery via the retroactive control circuit.

This is done by imposing a high current charge until the charging is complete. The LED LD2 will indicate that charging is full which will eventually deactivate the charging circuit. In creating this design, the cables that connect the transformer to the circuit should have enough cross-sectional area to prevent voltage drop when heat is produced as the current flows through. The adjustment of the circuit comes after the design, with the adjustment of TR1 to null value.

The LEDs are checked without connecting the battery initially and allowing them to turn ON. By connecting a battery, a 2A to 4A current is permitted to flow while ensuring that LD2 is turned OFF. TR1 is carefully adjusted to a few hundred milliamps until LD2 turns ON. This is done using the hydrometer technique. The correct adjustment allows LD2 to begin flickering as the battery is being charged. Connected to the battery is Q1, since it functions as a rectifier and charges the battery, which can be fired in each half cycle by R3-4 and LD2.

In case an uncharged battery is connected, a low terminal voltage is obtained. When the voltage of the battery exceeds the predetermined value, Q2 is activated by the combination of C1, TR1, R2, and D2. Q1 is deactivated with the current supply cut off as the battery terminal voltage is increased where Q2 shifts the control of Q1 gate after TR1 fixed the increased battery terminal voltage above the level. A heat sink should be mounted on the bridge rectifier GR1 and Q1 to prevent overheating. A 5A DC ammeter M1, connected in parallel, is used to measure the charge current.

The circuit’s theory of design will only be applied to batteries with rating of 12V. These batteries are mainly used in a variety of vehicles used in land, air, and water such as personal watercraft like boat, yacht, Jet Skis, and other marine applications. They are also utilized widely in automobiles and motorcycles such as quad bike, RVs, snowmobile, motor scooter, utility vehicle, and riding mower. It can also be beneficial to disabled persons by providing aid to wheelchairs and mobility scooters.

Parts:


R1= 1Kohms
R2= 1.2Kohms
R3= 470 ohms
R4= 470 ohms
R5= 10Kohms
C1= 10uF 25V
D1= 1N4001
D2= 6.8V 0.5W zener
TR1= 4.7Kohms trimmer
Q1= BTY79 or similar 6A SCR
Q2= C106D SCR
GR1= 50V 6A Bridge Rectifier
T1= 220V/17V 4A Transformer
LD1= Green LED
LD2= Red LED
M1= 0-5A DC Ampere meter
S1= 10A D/P On Off Switch
F= 5A Fuse
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Saturday, December 21, 2013

Four Tone Siren

UM3561 PROJECT CIRCUIT

        UM3561 IC includes  oscillator and selector circuits so few external component is used for construction of four tone siren.
   The UM3561 contains programmed mask ROM to simulate siren sound. Power consumption of IC is low.It is powered by 3 Volt. One NPN Transistor is used for amplification of audio signal.

       Circuit Diagram of Four Tone Siren
Part List :
IC UM3561
Resistance = 220 Ohms
Condenser 100Mfd
Transistor BC548
Battery Container 3V
Switches
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Thursday, December 19, 2013

Outdoor Lighting Controller

When you step out of your brightly-lit house  into the darkness, it takes a while for your  vision to adjust. A solution to this problem  is this outdoor light with automatic switch-off. As a bonus, it will also make it a little bit  easier to find the keyhole when returning  late at night. Often no mains neutral connection is avail-able at the point where the switch-off timer  is to be installed, which makes many circuit  arrangements impractical. However, the circuit here is designed to work in this situation. The design eschews bulky components such as transformers and the whole unit can  be built into a flush-mounted fitting. The circuit also features low quiescent current consumption.

Outdoor Lighting Controller Circuit Diagram :

Outdoor Lighting Controller-Circuit Diagram

The circuit is star ted by closing switch (or  pushbutton) S1. The lamp then immediately receives power via the bridge rectifier. The drop across diodes D5 to D10 is 4.2 V, which provides the power supply for the delay circuit itself, built around the CD4060 binary  counter.

When the switch is opened the lighting sup-ply current continues to flow through Tri1. The NPN optocoupler in the triac drive circuit detects when the triac is active, with antiparallel LED D1 keeping the drive sym-metrical. The NPN phototransistor inside the  coupler creates a reset pulse via T1, driving  pin 12 of the counter. This means that the  full time period will run even if the circuit is retriggered. The CD4060 counts at the AC grid frequency.  Pin 3 goes high after 213clocks, which corresponds to about 2.5 minutes. If this is not long  enough, a further CD4060 counter can be cascaded. T2 then turns on and shorts the internal LED of opto-triac IC2; this causes Tri1 to  be deprived of its trigger current and the light  goes out. The circuit remains without power until next triggered.

The circuit is only suitable for use with resistive loads. With the components shown (in particular in the bridge rectifier and D5 to  D10) the maximum total power of the connected bulb(s) is 200 watts. As is well known, the filament of the bulb is most likely to fail at the moment power is applied. There is little risk to Tri1 at this point as it is bridged by  the switch. The most likely consequence of overload is that one of diodes D1 to D6 will  fail. In the prototype no fuse was used, as it would not in any case have been easy to change. However, that is not necessarily recommended practice!

Circuits at AC line potential should only be constructed by suitably experienced persons and all relevant safety precautions and  applicable regulations must be observed during construction and installation.
Author : Harald Schad - Copyright : Elektor

Source  : http://www.ecircuitslab.com/2012/09/outdoor-lighting-controller.html

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Tuesday, December 17, 2013

123 Game All MCU Free

This electronic game pits a human player against the ‘machine’. The opponents use a common ‘game token’ and take turns moving along a path by one, two or three steps, and the winner is the first one to reach the goal exactly. Incredibly enough, this simple version of the ‘123’ game can be built without a microcontroller, and it’s almost impossible to beat. The electronics for this is built using only diode logic (Figure 1).

123 Game - All MCU-Free
123 Game Circuit Diagram - All MCU-Free
The ‘ input inter face’ consists essentially of 30 miniature sockets to which a probe tip can be connected to mark the position of the ‘game token’. To make the game more compact, the sockets are arranged in a grid so the route along the sockets follows a serpentine path (Figure 2). The starting position is at the bottom right, and the goal is in the middle of the playing area. The electronics becomes the ‘active player’ when the button is pressed.

The number of steps it wants to move is shown by three LEDs (one, two or three LEDs light up) at the top of the playing area. Naturally, the human player must move the ‘game token’ for the machine opponent. The winner is the first one to reach the goal exactly. How can such simple circuitry represent such a formidable opponent? As already mentioned, the path from the start to the goal is formed by 30 sockets. Each socket has an associated ideal next move.

There are three possibilities, of course: 1, 2 or 3. As you can see from the schematic diagram, switch S1 closes the circuit (which means the player asks the ‘computer’ how many steps it wishes to move) if the probe is touching one of the sockets. All 30 sockets are classified into three types, represented in the schematic diagram by one socket for each type. All sockets belonging to a particular type are simply connected together electrically, which is not shown on the schematic diagram for the sake of clarity.

This is how the LED display works:


The player touches the right-hand contact with R4 (only LED D3 lights up), the left-hand contact with R3 (LEDs D1 and D2 light up), or the middle contact with diodes D4 and D5 (all three LEDs light up). The two diodes prevent all three LEDs from lighting up if the player touches the left-hand or right-hand contact. The key to all this lies in the assignment of the 30 sockets to the three types of logic, which means the three types of ideal next move.

Working backward from the goal, no further move is possible when the goal is reached. For this reason, the last socket is not connected to anything. At the socket just before the goal, the ‘computer’ naturally wants to be exactly one step in front. Consequently, this socket is connected to R4. At the second socket before the goal, the electronics wants to move by two steps. This socket is thus connected to R3.

Obviously, three moves before the finish, a three-step is best as it leads to instant victory. Consequently this socket is connected to D4/D5. The correct response of the ‘computer’ is shown in Figure 2 by the number next to each position. As the two opponents take turns playing, the electronics always tries to arrive at a strategically favourable position (marked by the arrows). If the electronics manages to reach one of these positions, it’s impossible for the human player to win. This means that the human player can only win by starting first and always making the right move.
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