Thursday, June 30, 2011


1.25V-15.19V Regulator/Adaptor Variabel Digital, is a series regulator with variable output from the digital 1.25V to 15.19V The first section of the circuit comprises a digital up-down counter built around IC1, a quad 2-input NAND Schmitt trigger (IC CD4093), followed by IC2, a binary up-down counter (CD4029 IC). Two gates of IC CD4093 are used to generate the up-down logic using the push buttons S1 and S2, respectively, while the other two gates form an oscillator to provide clock pulses to IC2 (CD4029). The frequency of oscillations can be varied by changing the value of capacitor C1 or preset VR1. IC2 receives clock pulses from the oscillator and produces a binary sequential output. As long as its pin 5 is low, the counter continues to count at the rising edge of each clock pulse, but stops counting as soon as its pin 5 is brought to logic 1. Logic 1 at pin 10 makes the counter to count upwards, while logic 0 makes it count downwards. Therefore the counter counts up by closing switch S1 and counts down by closing switch S2. The output of counter IC2 is used to realize a Digitally variable resistor.
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This Power amplifier circuit produces output power up to 300 watts ( 8ohms) pada masing-masing channelnya. 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. CIRCUIT mute function, when activated, mutes the input drive signal and forces the amplifier output to a quiescent state.
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The voltage drop across the resistors R2 and R3, are used as the input of the Darlington pairs.
 As the input current to the op-amp depends on the level of the signal op amp is amplifying
the voltage drop across the resistors R2 and R3 will be proportional to the input signal.
These voltage drops are given to the base of Darlington pairs. The amplification is stabilized
as a result of the negative feedback from the junction of collectors of Q2 and Q4.
The theory may seem little awkward for you.But its working good.Such a simple but stable
circuit as this can produce a reasonable output of 12W on a 4 Ohm speaker.
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10-Band Graphic Equalizer Circuit Diagram, As shown in the diagram, there are 10 same units that only differ in capacitance values of
capacitors which determine the frequency band of each filter. The potentiometers adjust
the predetermined regions of frequency in each unit.

The components must be high quality and have low tolerance, Specifically potesometer RV1.
the 10 and capacitors. The resistors must be metal-film type.

If it is intended for stereo use then it will be supposed it is made in two pieces with as
much as possible suited the materials, between the channels, so that do not exist differences
in the regulation of each band frequencies.
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The amplifier circuit can be run from 3Volt. This Mercury is ideal for battery
operated module. The potentiometer circuit can be used to control volume. Capacitor C1 and C2
are designed to filter supplyvoltage If the battery separator is used as operations offer
source.For using batteries C1 and C2 are not required.

TDA7052 is a mono output amplifier in 8-comng Head DI package (DIP).
The device is designed primarily for battery-operated portable audio circuits.
Features include TDA 7052, no external components needed, no switch-on or switch-off button.
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Tuesday, June 21, 2011

Heat Sensor Circuit

This is the simple heat sensor circuit. It can be used to control any device using heat sensor. In this circuit a thermistor and a resistance is connected in series. This arrangement makes a potential divider circuit.

Here the thermistor is Negative Temperature Coefficient type. So when the room temperature is increased its resistance decreases simultaneously and more current flows through the resistor and the thermistor. We find more voltage at the junction of the resistor and the thermistor.
Our thermistor resistance value is 110 ohms. Suppose the resistance value becomes 90 ohms after heating the 110 ohms thermistor. Then the voltage across one resistor of the voltage divider circuit equals the ratio of that resistor’s value and the sum of resistances of the voltage across the series combination. This is the concept of voltage divider. 

The final output voltage of the voltage divider circuit is now applied to the npn transistor (BC548) through the base resistor (3.3K ohms). Here the emitter resistor is replaced with a zener diode. Emitter voltage is maintained at 4.7volt with the help of zener diode. This voltage is used to compare voltage. Transistor conducts when base voltage is greater than the emitter voltage. Transistor conducts if it gets more than 4.7volt of base voltage. Then the circuit is completed through buzzer and it gives sound.

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Monday, June 20, 2011

Active FM Antenna Amplifier of FM Booster

FM booster is one kind of a preamplifier which can be used to listen FM radio programs from distance FM stations clearly. The circuit comprises a common-emitter tuned RF preamplifier which tuned RF preamplifier wired around VHF/UHF transistor 2SC2570.

Parts Lists

22pF Trimmer capacitor

Adjust input/ output trimmers (VC1/VC2) for maximum gain.
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Wednesday, June 15, 2011

3 digits Digital Ammeter using Microcontroller

Digital Ammeter is needed to do any kind of electronics circuit making. It is very much useful who is interested in electronics projects. Now-a-days there are many kind of digital or analog ammeter which are found in the market. But if you make such kind of digital meter then you have no no bounds happy.

The bellow circuit is digital Ammeter based on PIC16F684 and ACS712 current sensor. Here the measured ac/dc current will display on three digit 7-segment  with resolution 100mA. In this project current sensor is ACS712ELCTR-30A-T . This circuit can measure the ac or dc current up to 30mA with 66mV/A output sensitivity.

The micro-controller PIC16F684 is used to read analog value from the ACS712 current sensor output and micro-controller convert to current and displaying on 7-segments display. For this circuit all 7-segment displays will be common anode type and it driven by PNP transistor BC557. Originally, this circuit is suitable for measuring DC current.

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Remote Control Using the NE 555 and LM 567

Remote control circuit consists of two parts, one is transmitter and the other is receiver. A simple diagram is schematic remote control. The transmitter circuit’s transmitter IC is controlled by NE555. Receiver circuit works by the signal emitted frequency which is emitted by that transmitter circuit. Transmitted signal frequency must be equal to the frequency decoder of the receiver circuit. The NE 555 generated frequency is same that receive frequency of IC LM 567. 

The output frequency of the transmitter circuit is f,
f = 1.44/(Ra+2Rb)C
The resistor R1 is a receiver variable to facilitate the process of tuning. The system works well when the circuit is ready. The first step is tuning by way of the transmitter is turned on continuously, while the receiver R1 to set the value to be able to detect the signal transmitter. The second part is the receiver is controlled by LM 567. The following is a schematic drawing recipient.

f = 1 / (1.1 xR1xC1)
This frequency depends on the value of R1 and C1.

In the picture on top of each channel is designed with a different frequency. By considering the bandwidth of the frequency detection signal LM 567, inter-frequency channels should have a big enough difference, let’s try with a difference of 5 KHz.

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Sunday, June 12, 2011

IR Remote Control Circuit using Op amp 741

IR circuit is called Infrared Circuit. Remote controls are very much popular now-a-days. It is specially called cordless circuit. This circuit is very simple and low cost cordless remote control circuit which is based on infrared   rays.

Figure 1 shows the transmitter circuit. The transmitter produces infrared rays and that can be easily transmitted up to 4 meters with a special convex lens and a twin LED arrangements.
Figure 2 shows the receiver  circuit. Op amp IC1-741 generates high frequency squire wave which provides the gate pulses for SCR1. IC1’s output current flows through  SRC1 and it is conducting current and enables the LED to emits infrared rays. The output frequency of Op amp IC1 depends on the variable resistor VR1, which in turns varies the output radiations of the LED.

When IR rays fall on the photo-transistor T1 of the receiver, then base of the photo-transistor’s base produces charge carriers at a rate depending on the rate of arrival of incident radiations at the pn junction of the transistor. Then the resulting emitter voltage is amplified by Op amp IC-2 . The amplified signal is rectified by D2. Finally the amplified signal is to drive the relay.

Parts List:

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