Figure gives the circuit diagram of 2X12 W Hi-Fi Amplifier. This amplifier circuit is based on TDA 2616 IC which is the core part of this circuit. The TDA2616 is a stereo power amplifier IC. It is a 9-lead single-in-line (SIL9) plastic power package (SOT131). This amplifier IC finds applications in mains fed amplifier circuits such as stereo radio, tape and television. It has gain balance for both of the channels and hi-fi according to standards such as IEC 268 and DIN 45500. This IC has special inbuilt circuit for the suppression of noise signals at the inputs, during switch-on and switch-off. This avoids click sounds during power on and power off.

Simple and less number of components make this circuit suitable for portable power amplifier circuits. A well regulated and filtered +/- 12 V dual power supply is used in this circuit to provide at least 2 A continuous current. The circuit can deliver a maximum output of 12 W power on 8 Ohm speaker for each channel at +/- 12 V dual supplies. This Hi-fi amplifier circuit can complement your audio system with ceiling speakers for home theater.

Circuit Diagram

Hi-Fi Amplifier Circuit

Notes

• Use a good quality PCB to assemble this particular circuit.
• IC TDA 2616 is from Philips.
• All capacitors except C10 & C9 are ceramic type.

Police siren circuit given here is a circuit based on NE 555 timer IC. This circuit uses two NE 555 ICs (IC1 and IC2) and which are the core working parts of this circuit. Here two timer ICs are wired to work as astable multivibrators. But these two timer ICs are working at different frequencies. IC1 is slow astable multivibrator operating at a frequency of 20Hz and a duty cycle of 50% whereas IC2 works at 600Hz as fast astable multivibrator. The output of IC1 is fed to the control pin (pin5) of IC2. By this connection, the output frequency of IC2 will be modulated with the output frequency of IC1.

The circuit can be powered from a DC supply voltage ranging between 6V and 15V. Power supply used here is 12V DC supply. The loudness of output can be further increased by inserting a power amplifier circuit at the output stage of this circuit.

Circuit Diagram

555 Timer Police Siren Circuit

Notes

• Use a Perf board to assemble this circuit.
• The output frequency of IC2 is controlled by the output of IC1.
• One NE 556 IC can be used instead of two NE 555 ICs.

Use speaker with rating 64 ohm, 500mW.

The circuit diagram given here is a simple voltage doubler circuit. In this circuit the central part is the timer IC NE 555. This circuit also includes two transistors Q1 (BC 107) and Q2 (BC 177) as its main part. The actual output current delivered by this circuit is 50 mA and it is suitable only for low current applications. The output voltage of this circuit will be approximately 19V for 12V DC input voltage.

In this circuit, the IC1 NE 555 acts as astable multivibrator operates at a frequency of 9 KHz. The output of this astable multivibrator is connected to the base of the transistors Q1 and Q2. The capacitor C3 is connected in such a way that its negative terminal is shorted to the output of two transistors. When the output of the astable multivibrator becomes low, Q1 will be off and Q2 will be on and capacitor charges. When the output of astable multivibrator goes high, reverse will happen and capacitor again charges to the double of the supply voltage. So the final output across capacitor C4 will be the double of the input voltage.

Circuit Diagram

Voltage Doubler Circuit

Notes

• Use a Vero board to assemble this circuit.
• Use a holder to mount IC1.

The circuit given here is a three phase auto charger circuit. Any modern electrical or electronic device can operate from 230 V ac supply with 15% tolerance in voltage. That is the device will work normally for a voltage range between 195V and 265V. The device may not work properly beyond this range of voltage. To change over to the other phase, the voltage required for can be chosen. Here in this circuit, a step down transformer with a secondary voltage of 15-0-15 volt at 500 mA is used for the operation of 18V relay. Here switching of the relay can be controlled by the resistors R3 and R1 respectively.

Circuit diagram

3-Phase Auto-Changer Circuit

Connection diagram

3-Phase Auto changer circuit-Connection Diagram

Notes

• The circuit given here is designed by Mr.Seetharaman V.S from Chennai.
• Transformer T1 can be a 15-015 V secondary, 230V primary, 500mA step down transformer.
• For chatter free operation, use a capacitor of 100μF 40 volts in parallel with relay.
• Use one mould for each phase.
• The connection diagram given above gives the relay interconnections.

Here is the circuit diagram of Baxendall tune control circuit. The name Baxendall for this circuit is because this circuit is based on the tune control circuit developed by Baxendall. This circuit uses two transistors Q1 and Q2 (BC 109C) which are the central active components in this circuit. This circuit can produce a maximum cut or boost of around 12 dB at 10 KHz (treble) and 50Hz (bass).

The whole circuit consists of three stages such as input stage, Baxendall circuitry and output stage. The input stage is an emitter follower centered on transistor Q1 and consisting of resistors R1 (560K), R2 (470K) and R3 (2.2K). This input stage has unity gain and the output of this stage is fed to the Baxendall stage through the capacitor C1 (10 uF). Potentiometers R7 and R10 (47K) are used for the adjustment of bass and treble respectively. The output stage of this circuit consists of transistor Q2 and resistors R11 (2.7M), R12 (10K) and R13 (2.2K). The output of second stage is given to the output stage and the final audio output is produced from the output stage with a gain of three.

Circuit diagram

Baxendall Circuit

Notes

• Assemble the circuit on a good quality PCB.
• A 12V DC supply is used for powering this circuit.
• Both the bass and treble can be independently adjusted.
• The input stage of this circuit has an impedance of 225 kilo ohms.

The circuit diagram of FM remote encoder/decoder has been published here. The main parts of this circuit are the ICs RF 600E and RF 600D. This circuit consists of two main parts such as transmitter (encoder) section and receiver (decoder) section. Among these, the transmitter stage uses IC1 (RF 600E) as its core part and the receiver stage uses IC2 (RF 600D) as its core part. These devices are designed to provide a high level of security and it can operate from DC supply between 2 to 6.6V DC.

In the encoder section, pins 1 to 4 forms the switch inputs of IC1. When each push button switch is pressed a corresponding code will be generated at the pin 6 which is the output pin. Transistor Q1 is used for buffering the encoded signals.  After buffering, this signal is given to the FM transmitter module. In the decoder section based on IC2 has four digital data output pins (pins 17, 18, 1 and 2) corresponding to the switches S1 to S4 of the transmitter section. The receiver module receives the transmitted code and feds it to the data input (pin 9). After the signal processing in IC2 the transmitted signal will be obtained.

Circuit diagram

FM REMOTE ENCODER CIRCUIT

FM Remote Encoder Circuit

FM REMOTE DECODER CIRCUIT

FM Remote Decoder Circuit

Notes

• Assemble the circuit on a good quality PCB.
• The ICs can be operated from anything between 2V to 6.6V. It is better to use batteries for powering this circuit.
• Use miniature push button switches for S1 to S5.
• Various electronic circuits like remote control systems, remote alarm systems, anti theft alarms etc can be implemented using the RF600E/RF600D pair.

]]> http://amplifierlab.com/fm-remote-encoderdecoder-circuit/2010/06/09/feed 2 http://amplifierlab.com/switching-regulator-circuit/2010/06/09 http://amplifierlab.com/switching-regulator-circuit/2010/06/09#comments Wed, 09 Jun 2010 09:57:18 +0000 admin http://amplifierlab.com/?p=301 Circuit Description

The circuit diagram of 3A switching regulator has been published here. The central part of this circuit is the IC LM 317. This voltage regulator can deliver a maximum output current of 3A. The input voltage range of this circuit is between 8 and 35V DC. The output voltage of the circuit can be adjusted between 1.8 to 32V DC. The output voltage is adjusted by using the potentiometer R4 (5K). One of the main advantages of switching regulators over liner regulators is its power efficiency.

Switching regulator operates by taking energy from the input voltage source and then transferring it to the output with the help of a solid state switch and a control circuitry. There is no wastage of energy in switching voltage regulators since the switching element is either fully open or closed at any moment. The efficiency of switching voltage regulators is around 85%. The rate of energy transfer from input to output is controlled by the control circuit by controlling the duty cycle of the solid state switch.

Circuit Diagram

Switching Regulator Circuit

Notes

• Use a good quality PCB to assemble this circuit.
• The electronic circuit given here is a simple and low cost switching regulator.
• Adequate heat sinks should be provided for IC1 and Q1.
• Capacitor C1 must be a solid tantalum capacitor.

]]> http://amplifierlab.com/switching-regulator-circuit/2010/06/09/feed 1 http://amplifierlab.com/microphone-pre-amplifier-circuit/2010/06/02 http://amplifierlab.com/microphone-pre-amplifier-circuit/2010/06/02#comments Thu, 03 Jun 2010 05:57:29 +0000 admin http://amplifierlab.com/?p=297 Circuit Description

Here is the circuit diagram of three input microphone preamplifier. This is a mic mixer preamplifier centered on the high gain operational amplifier IC LM 348. This IC LM 348 is a quad operational amplifier IC that is it has four operational amplifiers embedded in this chip. This IC has also got some advanced features such as very high gain, class AB output stage and very low input supply current of 0.6 mA for each op-amp.

The 3 channels of mic input require three amplifiers. The three op-amps (IC1b, IC1c and IC1d) out of four in the IC LM 348 are used here as input amplifiers for the corresponding channels. This three input amplifiers are made in this circuit work as non-inverting amplifiers. The operational amplifier IC1a is the output amplifier in this circuit. IC1a is wired as inverting amplifier here. The output from each input amplifiers are given to the inverting terminal of output op-amp. IC1a mixes the signals from each channel and produces the required output.

Circuit diagram

Microphone Pre-amplifier Circuit

Notes

• Use a good quality PCB to assemble this circuit.
• IC LM 348 operates from a dual power supply. A +12/-12V DC dual supply is used here for powering the circuit.
• The gain of individual channels can be adjusted by using potentiometers R5, R6 and R7.

The circuit diagram of simple capacitance meter has been published here. The core part of this circuit is the frequency to voltage converter IC LM 2917 developed by National Semiconductors. This IC LM 2917 is a monolithic IC having a very high gain. This IC has got its primary application in tachometers. It can also be used for other applications as well.

This is a capacitor measurement circuit that displays capacitance by using a meter M1. The capacitor Cx whose capacitance is to be measured is connected between the pin2 of the IC and ground. The capacitance Cx will be proportional to the output voltage of the IC. At the output pin (pin4), a resistor R2 (10K) is connected as load. The voltage across this is displayed through a voltmeter (M1) which is connected across R2.

Circuit Diagram

Capacitance Meter Circuit

Notes

• Use a Vero board to assemble this particular circuit.
• Use a suitable holder to mount the IC LM 2917.
• Capacitance values from 0.01uF to 0.1uF can be measured using this circuit.
• Potentiometer R1 (200K) can be used for calibrating this circuit.
• Use a 10V FSD voltmeter in place of M1.

The circuit diagram of light activated switch circuit has been described here. The core part of this circuit is the operational amplifier IC LM 311which acts as a voltage comparator here. This circuit also consists of an LDR which senses light intensity. A transistor Q1 (BC 107) is included in this circuit for driving the relay.

The non-inverting terminal of comparator is given with 6 V fixed voltage by using resistors R3 and R4 (10K). The voltage at the inverting terminal is the voltage across LDR which is variable according to the intensity of light falling on it. When light intensity is low (darkness), the resistance of LDR will be high and hence the voltage across it. Then the output of comparator will become low and relay becomes inactive. If light intensity increases, the resistance of LDR decreases. As a result of this comparator output will become high and it turns on relay. So relay switches according to the light intensity and which is the desired output of this circuit.

Circuit Diagram

Light Activated Switch

Notes

• Use a good quality PCB to assemble this circuit.
• Adjust potentiometer R1 to set the desired light intensity for switching the relay.
• Use a 12 V battery or 12V DC regulated power supply for powering this circuit.
• The chance of oscillation in this circuit can be minimized by shorting the pins 5 and 6 of IC LM 311.

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