Music box versatile using IC M3481

This is a multi-purpose integrated music box that interesting, because an IC package. Is a simple and affordable.

The main function of the circuit is the device of the circuit is IC1. This is a sound generator IC. The Christmas season. Its musical all 8 music. When the power supply LDR1 the exposure will cause voltage drop across R1 is enough to make IC1 work has output to stimulate pin 11 and pin 12 to stimulate pin B of Q1. Q2 and the current expansion drive that will be the speaker. While the circuit work if the switch S1 connected to the unique music tracks and so on, but if S1 is not connected. Circuit will play all the songs. If the switch S2 connected to the cycle When there is no light will stop play immediately. But if the switch S2 is not connected to music and no light will not stop until the song is finished playing. Switch S3 is responsible for selecting music on, press 1 once one moves to music. The VR1 is also a tone control if VR1 is less resistance will be reduced to a lower tone. And the music will slow down play with. The R6, C3 is responsible for smooth sound more R7 forward to control the feedback stability of dc output of the circuit.

Battery-Charging Indicator For Mains Adaptor

Although you may well be the proud owner of the very latest NiCd battery charger, you may still come across the odd 'incompatible' battery, for example, one having a rare voltage or requiring a much higher charging current than can be supplied by your off-the-shelf charger. In these cases, many of you will resort to an adjustable mains adaptor (say, a 500-mA type) because that is probably the cheapest way of providing the direct voltage required to charge the battery. Not fast and not very efficient, this 'rustic' charging system works, although subject to the following restrictions:

Circuit diagram:

Battery-Charging Indicator Circuit Diagram
You should have some idea of the charging current. In case you use an adaptor which is adjustable but of the unregulated, low output current type, you can adjust the current by adjusting the output voltage.
You have to know if the current actually flows through the battery. A current-detecting indicator is therefore much to be preferred over a voltage indicator.
To prevent you from forgetting all about the charging cycle, the indicator should be visible from wherever you pass by frequently. Using the circuit shown here, the LED lights when the baseemitter potential of the transistor exceeds about 0.2 V. Using a resistor of 1 ? as suggested this happens at a current of about 200 mA, or about 40 mA if R1 is changed to 4.7?. The voltage drop caused by this indicator can never exceed the base-emitter voltage (UBE) of the transistor, or about 0.7V. Even if the current through R1 continues to increase beyond the level at which UBE = 0.7 V, the base of the transistor will 'absorb' the excess current. The TO-220 style BU406 transistor suggested here is capable of accepting base currents up to 4A. Using this charging indicator you have overcome the restrictions 2 and 3 mentioned above.

USB Power Injector For External Hard Drives

A portable USB hard drive is a great way to back up data but what if your USB ports are unable to supply enough "juice" to power the drive? A modified version of the Silicon Chip Usb Power Injector is the answer. For some time now, the author has used a portable USB hard drive to back up data at work. As with most such drives, it is powered directly from the USB port, so it doesn’t require an external plug pack supply.

In fact, the device is powered from two USB ports, since one port is incapable of supplying sufficient current. That’s done using a special USB cable that’s supplied with the drive. It has two connectors fitted to one end, forming what is basically a "Y" configuration (see photo). One connector is wired for both power and data while the other connector has just the power supply connections. In use, the two connectors are plugged into adjacent USB ports, so that power for the drive is simultaneously sourced from both ports.

An external USB hard drive is usually powered by plugging two connectors at one end of a special USB cable into adjacent USB ports on the computer. This allows power to be sourced from both ports. According to the USB specification, USB ports are rated to supply up to 500mA at 5V DC, so two connected in parallel should be quite capable of powering a portable USB hard drive – at least in theory.

Unfortunately, in my case, it didn’t quite work out that way. Although the USB drive worked fine with several work computers, it was a "no-go" on my home machine. Instead, when it was plugged into the front-panel USB ports, the drive repeatedly emitted a distinctive chirping sound as it unsuccessfully tried to spin up. During this process, Windows XP did recognise that a device had been plugged in but that’s as far as it went – it couldn’t identify the device and certainly didn’t recognize the drive.

Plugging the drive into the rear-panel ports gave exactly the same result. The problem wasn’t just confined to this particular drive either. A newly-acquired Maxtor OneTouch4 Mini drive also failed to power up correctly on my home computer, despite working perfectly on several work computers.

The revised USB Power Injector is essentially a switch and a 5V regulator. The Vbus supply from USB socket CON1 turns on transistor Q1 which then turns on power Mosfet Q2. This then feeds a 6V DC regulated supply from an external plug pack to regulator REG1 which in turn supplies 5V to USB socket CON2.

White LED Lamp

Nowadays you can buy white LEDs, which emit quite a bit of light. They are so bright that you shouldn’t look directly at them. They are still expensive, but that is bound to change. You can make a very good solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of around 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors. The converter shown here generates a voltage that is high enough to allow ten LEDs to be connected in series. In addition, this converter supplies a constant current instead of a constant voltage.

A resistor in series with the LEDs produces a voltage drop that depends on the current through the LEDs. This voltage is compared inside the IC to a 1.25-V reference value, and the current is held constant at 18.4 mA (1.25 V ÷ 68 Ω). The IC used here is one of a series of National Semiconductor ‘simple switchers’. The value of the inductor is not critical; it can vary by plus or minus 50 percent. The black Newport coil, 220 µH at 3.5 A (1422435), is a good choice. Almost any type of Schottky diode can also be used, as long as it can handle at least 1A at 50V. The zener diodes are not actually necessary, but they are added to protect the IC. If the LED chain is opened during experiments, the voltage can rise to a value that the IC will not appreciate.

Resistors:
R1 = 1kΩ2
R2 = 68Ω
Capacitors:
C1 = 100µF 16V radial
C2 = 680nF
C3 = 100µF 63V radial
Inductors:
L1 = 200µH 1A
Semiconductors:
D1 = Schottky diode type PBYR745 or equivalent
D2-D5 = zener diode 10V, 0.4W
D6-D15 = white LED

Mains Powered White LED Lamp

Did it ever occur to you that an array of white LEDs can be used as a small lamp for the living room? If not, read on. LED lamps are available ready-made, look exactly the same as standard halogen lamps and can be fitted in a standard 230-V light fitting. We opened one, and as expected, a capacitor has been used to drop the voltage from 230 V to the voltage suitable for the LEDs. This method is cheaper and smaller compared to using a transformer. The lamp uses only 1 watt and therefore also gives off less light than, say, a 20 W halogen lamp. The light is also somewhat bluer. The circuit operates in the following manner: C1 behaves as a voltage dropping ‘resistor’ and ensures that the current is not too high (about 12 mA).

The bridge rectifier turns the AC voltage into a DC voltage. LEDs can only operate from a DC voltage. They will even fail when the negative voltage is greater then 5 V. The electrolytic capacitor has a double function: it ensures that there is sufficient voltage to light the LEDs when the mains voltage is less than the forward voltage of the LEDs and it takes care of the inrush current peak that occurs when the mains is switched on. This current pulse could otherwise damage the LEDs. Then there is the 560-ohm resistor, it ensures that the current through the LED is more constant and therefore the light output is more uniform.

There is a voltage drop of 6.7 V across the 560-Ω resistor, that is, 12 mA flows through the LEDs. This is a safe value. The total voltage drop across the LEDs is therefore 15 LEDs times 3 V or about 45 V. The voltage across the electrolytic capacitor is a little more than 52V. To understand how C1 functions, we can calculate the impedance (that is, resistance to AC voltage) as follows: 1/(2π·f·C), or: 1/ (2·3.14·50·220·10-9)= 14k4. When we multiply this with 12 mA, we get a voltage drop across the capacitor of 173 V. This works quite well, since the 173-V capacitor voltage plus the 52-V LED voltage equals 225 V. Close enough to the mains voltage, which is officially 230 V.

Moreover, the latter calculation is not very accurate because the mains voltage is in practice not quite sinusoidal. Furthermore, the mains voltage from which 50-V DC has been removed is far from sinusoidal. Finally, if you need lots of white LEDs then it is worth considering buying one of these lamps and smashing the bulb with a hammer (with a cloth or bag around the bulb to prevent flying glass!) and salvaging the LEDs from it. This can be much cheaper than buying individual LEDs…

CIRCUIT DIAGRAM 

Power Buzzer

How often on average do you have to call members of your family each day to tell them that dinner is ready, it’s time to leave, and the like? The person you want is usually in a different room, such as the hobby room or bedroom. A powerful buzzer in the room, combined with a pushbutton at the bottom of the stairs or in the kitchen, could be very handy in such situations. The heart of this circuit is formed by IC1, a TDA2030. This IC has built-in thermal protection, so it’s not likely to quickly give up the ghost. R1 and R2 apply a voltage equal to half the supply voltage to the plus input of the opamp. R3 provides positive feedback. Finally, the combination of C2, R4 and trimmer P12 determines the oscillation frequency of the circuit.Power Buzzer Circuit Diagram ...

How Make Simple Battery Isolator

This circuit is even simpler and employs a 6V feed from one of the stator connections on the vehicle’s alternator. This is connected to a 6V automotive relay (RLY1) which controls a Continuous Duty Solenoid (RLY2). This solenoid electrically connects or isolates the batteries. When the engine is started and the alternator stator voltage rises, the 6V relay turns on. This turns on the Continuous Duty Solenoid to connect the two batteries in parallel. As long as the engine is running, the vehicle’s alternator will maintain charge in both batteries.
When the engine is shut down, the alternator stator voltage drops and the Continuous Duty Solenoid switches off, thus isolating the second battery from the vehicle’s electrical system. Provided that camping accessories are only connected to the second battery, the main battery should never discharge. Because the concept is entirely dependent upon the alternator’s stator output voltage, you cannot forget to turn the system on or off as it happens automatically.

SEVEN SEGMENT CIRCUIT

The IC 4511 is a BCD to 7-segment decoder driver. Its function is to convert the logic states at the outputs of a BCD, or binary coded decimal, counter like the 4510 into signals which will drive a 7-segment display. The display shows the decimal numbers 0-9 and is easily understood.

7-segment display

There are two important types of 7-segment LED display. In a common cathode display, the cathodes of all the LEDs are joined together and the individual segments are illuminated by HIGH voltages. In a common anode display, the anodes of all the LEDs are joined together and the individual segments are illuminated by connecting to a LOW voltage.

The 4511 is designed to drive a common cathode display and won't work with a common anode display. You need to check that you are using the right kind of display before you start building.

The 0.56 in. 7-segment display common cathode available from Rapid works well as part of a prototype board circuit.

When the 4511 is set up correctly, the outputs follow this truth table:

 

In normal operation, the lamp test and ripple blanking inputs are connected HIGH, and the enable (store) input is connected LOW. The circuit diagram shows the 4511 and a 7-segment common cathode display connected to the outputs of a 4510 BCD counter:

SEVEN SEGMENT CIRCUIT

To build this circuit follow the prototype board layout from the 4510 Beastie Zone web page and then add the 4511 with connections to a third prototype board, as shown below: 

SEVEN SEGMENT CIRCUIT

http://electrocircuitschema.blogspot.com/2010/12/seven-segment-circuit.html

NOT gates

The NOT gate has a single input and one output.

The little bubble on the output indicates that the output goes LOW when the input goes HIGH.

We can say that the output goes LOW when the input is ACTIVATED.

The opposite happens when the input is LOW. The output goes HIGH.

The TRUTH TABLE shows that the output is the opposite of the input.

The NOT gate is also called an INVERTER. It inverts the input.
_
The Boolean expression is A = Z

Which is read as, NOT A EQUALS Z

or IF A IS LOW THEN Z IS HIGH

or BAR A = Z

OR gates

The OR gate has two or more inputs and one output.

The output voltage goes high only when one or more input voltages are high.

In the switch diagram the lamp lights up when A OR B (or both) are operated.

In the truth table Z = 1 when A or B = 1.

The Boolean expression is A+B = Z which translated says, A or B high makes Z high.

The plus sign + translates as OR.

 

AND Gates

The AND gate has two or more inputs and one output.

The output voltage goes high only when all input voltages are high.

In the switch diagram the lamp lights up only when A and B are operated. If only one is switched then the lamp stays off.

In the truth table Z = 1 only when A and B = 1

The Boolean expression is A. B = Z which translated says, A and B both high, makes Z high.

 

Binary

In 1854, a central paper on binary systems was published by the mathematician George Boole. This paper laid out the groundwork for what would eventually be called Boolean algebra. With the advent of electronics, binary systems suddenly made incredible sense. Most electronic systems function on a switch-based system, with current either running or not running. In 1937, Claude Shannon set out the foundations for the theory of circuit design using binary arithmetic. In 1940, the age of binary computing began with the release of Bell Labs Complex Number Computer, which was able to perform extremely complex mathematical calculations using a binary system.
Binary numbers (1 or 0) represent on(1) or off(0).

Typically you work out binary like this:

256 128 64 32 16 8 4 2 1

If you have say a decimal number of 254, to work out the binary code you would use the system above to work it out. So,

256 128 64 32 16 8 4 2 1

0 1 1 1 1 1 1 1 0

The number that was given (254) is equated in the system above if you were to add up the numbers that have 1s underneath them.From there you can learn to translate binary into decimal, decimal into hexidecimal (not using binary,because hex is a whole other language base) which then goes onto C++ programming and all the rest.

If you're working out bigger numbers, for instance 3813, then you need to create a bigger system in order to work out the binary code so therefore you need to do this:

2048 1024 512 256 128 64 32 16 8 4 2 1

1 1 1 0 1 1 1 0 0 1 0 1

So this is your Binary Code for 3813:

1 1 1 0 1 1 1 0 0 1 0 1

If you want to be lazy you can just use your calculator on your computer. You need to switch the view to scientific which calculates binary, decimal, hex and octal. I suggest you make sure you understand binary code first before moving onto hex because the development between them can become very confusing.

Sound Effects Generator

Description:
This circuit uses a UM3561 IC to produce four different sound effects.

Notes:
Nothing too complicated here. The IC produces all the sound effects, the output at Pin 3 being amplified by the transistor. A 64 ohm loudspeaker can be substituted in place of the 56 ohm resistor and 8 ohm loudspeaker. The 2 pole 4 way switch controls the sound effects. Position 1 (as drawn) being a Police siren, position 2 is a fire engine sound, 3 is an ambulance and position 4 is a machine gun effect. The IC is manufactured by UMC and was available from Maplin electronics code UJ45Y. At the time of writing this has now been discontinued, but they have have limited stocks available.

24 Hour Timer Circuit

Circuit : Thelurunk
Description:
These two circuits are multi-range timers offering periods of up to 24 hours and beyond. Both are essentially the same. The main difference is that when the time runs out, Version 1 energizes the relay and Version 2 de-energizes it. The first uses less power while the timer is running; and the second uses less power after the timer stops. Pick the one that best suits your application.

 

 

The Cmos 4060 is a 14 bit binary counter with a built in oscillator. The oscillator consists of the two inverters connected to Pins 9, 10 & 11; and its frequency is set by R3, R4 & C3. The green Led flashes while the oscillator is running: and the IC counts the number of oscillations. Although it's a 14 bit counter, not all of the bits are accessible. Those that can be reached are shown on the drawing.

By adjusting the frequency of the oscillator you can set the length of time it takes for any given output to go high. This output then switches the transistor; which in turn operates the relay. At the same time, D1 stops the count by disabling the oscillator. Ideally C3 should be non-polarized; but a regular electrolytic will work, provided it doesn't leak too badly in the reverse direction. Alternatively, you can simulate a non-polarized 10uF capacitor by connecting two 22uF capacitors back to back (as shown).

Using "Trial and Error" to set a long time period would be very tedious. A better solution is to use the Setup tables provided; and calculate the time required for Pin 7 to go high. The Setup tables on both schematics are interchangeable. They're just two different ways of expressing the same equation.

For example, if you want a period of 9 Hours, the Range table shows that you can use the output at Pin 2. You need Pin 2 to go high after 9 x 60 x 60 = 32 400 seconds. The Setup table tells you to divide this by 512; giving about 63 seconds. Adjust R4 so that the Yellow LED lights 63 seconds after power is applied. This will give an output at Pin 2 after about 9 Hours. A suitable Veroboard layout for each version is shown below:
 

How to make Electronic Siren Circuit

The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off. When the push button switch is pressed to 10u capacitor will charge via the 22k resistor. This voltage is applied to the base of the BC108B which will turn on slowly. When the switch is released the capacitor will discharge via the 100k and 47k base resistors and the transistor will slowly turn off. The change in voltage alters the frequency of the siren. The oscillator action is more difficult to work out. As the BC108B transistor switches on its collector voltage falls and so the 2N3702 transistor is switched on. This happens very quickly ( less than 1us). The 22n capacitor will charge very quickly as well. As this capacitor is connected between the collector of the 2N3702 and the base of the BC108B, it soon reaches almost full supply voltage. The charging current for the capacitor is then much reduced and the collector emitter voltage of the 2N3072 is therefore increased; the collector potential will fall. This change in voltage is passed through the 22n capacitor to the base of the BC108B causing it to come out of saturation slightly. As this happens its collector voltage will rise and turn off the 2N3072 transistor more. This continues until both transistors are off. The 22n capacitor will then discharge via the 100k, 22k resistor, the closed push button switch, 9V battery, the speaker and 56 ohm resistor. The discharge time takes around 5-6msec. As soon as the 22n capacitor is discharged, the BC108B transistor will switch on again and the cycle repeats. The difference in voltage at the collector of the BC108B (caused by the charging 10u capacitor) causes the tone of the siren to change. As the 10u capacitor is charged, the tone of the siren will rise, and as it is discharged, it will fall. A 64 ohm loudspeaker may be used in place of the 8 ohm and 56 resistor, and the values of components may be altered to produce different sound effects.

About Zener Diode

The Zener diode is operated in reverse bias mode (positive on its cathode).
It relies on the reverse breakdown voltage occurring at a specified value.
This value is printed on it.

It has two main applications.

1. as a reference source, where the voltage across it is compared with another voltage.

2. as a voltage regulator, smoothing out any voltages variations occurring in the supply voltage across the load.

When being used a voltage regulator, if the voltage across the load tries to rise then the Zener takes more current.
The increase in current through the resistor causes an increase in voltage dropped across the resistor.
This increase in voltage across the resistor causes the voltage across the load to remain at its correct value.

In a similar manner, if the voltage across the load tries to fall, then the Zener takes less current.
The current through the resistor and the voltage across the resistor both fall.
The voltage across the load remains at its correct value.

Series Parallel Batteries

Resistors in Parallel

Resistors in parallel are connected across one another.
They all have the same voltage across them.

To find the equivalent resistance (the total resistance offered to the flow of current) we invert the values and add them. Then we invert the result.

For example take 2 ohms and 4 ohms in parallel.

Inverted 1/2 +1/4 = 3/4

Invert this 4/3 = 1.33 ohms

A quick check on your answer is that it should be smaller in value than the value of the smallest resistor.

If these resistors were connected across a 10 volt supply Ohms Law says about 7.5 amps would flow.

The formula can be written as 1/Rtotal = 1/R1 + 1/R2 + 1/R3 etc etc.

If only two resistors are involved then use (R1 x R2) divided by (R1 + R2)
For the 2 ohms and 4 ohms.
R1 x R2 = 8.
R1 + R2 = 6.
8/6 = 1.33 ohms

If you have several resistors of the same value in parallel then the equivalent resistance is the resistor value divided by the number of resistors.
For example, four 100 ohm resistors in parallel will provide a resistance of 25 ohms

How to make Resistors in Series

Resistors in series are connected in line.

The same current flows through them all.

The total opposition to the flow of current is called the EQUIVALENT resistance.
To find the value of the equivalent resistance we simply add the values.
In this case it is 30 ohms.

Note that, as a quick check on calculations, the value of the equivalent resistance is always higher than the value of the highest value resistance.

If these resistors were connected across a 30 Volt battery then Ohms Law says 1 amp would flow.

Electric Current

An electric current is a flow of microscopic particles called ELECTRONS flowing through wires and electronic components.
It can be likened to the flow of water through pipes and radiators etc.
As water is pushed through pipes by a pump, electric current is pushed through wires by a battery.
Hot water does work by heating radiators.
Electric current does work by heating fires, lighting lamps, ringing bells, electroplating etc.

A basic law of the universe is that like charges repel and unlike attract. Two negatives will repel each other. A negative and a positive will attract each other.
An electron has a negative charge.
The negative (-ve) terminal of a battery will push negative electrons along a wire.
The positive (+ve) terminal of a battery will attract negative electrons along a wire.

Electric current will therefore flow from the -ve terminal of a battery, through the lamp, to the positive terminal.

This is called electron current flow.

The current flows round the circuit.

In some books current is said to flow from +ve to -ve. This was guessed at before the electron was discovered. They guessed wrong! This is called conventional current flow.