Vocal Adaptor for Bass Guitar Amp Circuit Diagram

These days, music is a major hobby for the young and not-so-young. Lots of people  enjoy  making  music,  and  more  and  more dream of showing off their talents on stage. But one of the major problems often encountered is the cost of musical equipment. How many amateur music groups sing  through an amp borrowed from a guitarist or bass player? 

This is where the technical problems arise not in terms of the .25” (6.3 mm)  jack, but in terms of the sound quality (the words  are barely understandable) and volume (the amp  seems to produce fewer decibels than for a guitar). What’s more, unpredictable feedback may cause damage to the speakers and is very unpleasant on the ear. This cheap little  easy-to-build project can help solve these technical  problems.

A guitar (or bass guitar) amplifier is designed first and foremost to reproduce the sound of the guitar or bass as faithfully as  possible. The frequency response of the amp doesn’t need to be as wide or as flat as in hi-fi (particularly at the high end), and so this sort of amplifier won’t permit faithful reproduction of the voice. If you build an adaptor to compensate for the amp’s limited frequency response by amplifying in advance the frequencies that are  then attenuated by the amp, it’s possible to  improve the quality of the vocal sound. That’s  just what this circuit attempts to do. 

Circuit diagram :

Vocal Adaptor for Bass Guitar Amp Circuit Diagram

 

The adaptor is built around the TL072CN low-noise dual FET op-amp, which offers good value for money. The NE5532 can be used with almost the same sound quality, but at (slightly) higher cost. The circuit breaks  down into two stages. The first stage is used to match the input impedance and amplify the microphone signal. For a small 15 W guitar or bass amplifier, the achievable gain is  about 100 (gain = P1/R1). For more powerful amplifiers, the gain can be reduced to  around 50 by adjusting P1. The second stage amplifies the band of frequencies (adjustable using P2 and P3) that are attenuated by the guitar amp, so as to be able to reproduce the (lead)  singer ’s voice as clearly, distinctly, and  accurately as possible. To refine the adaptor and tailor it to your amplifier and speaker, don’t be afraid to experiment with the component values and the type  of capacitors. 

The circuit can readily be powered using a 9 V battery, thanks to the voltage divider R4/R5 which converts it into a symmetrical  ±4.5 V supply. [Link]

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Guards Amplifier Outputs Against Over-voltage Schematic

A universal requirement for automotive electronics is that any device with direct connections to the wiring harness must be able to withstand shorts to the battery voltage. Though brutal, this requirement is necessary for reliability and for safety. One example of the need for this protection is an audio amplifier that produces indicator noises in the automotive interior. Though operating from a voltage of 3.3 or 5V, which is lower than the battery voltage, the amplifier must be able to stand off the full battery voltage.

You can also use a protection network appropriate for these amplifiers for other automotive circuits (Figure 1). A dual N-channel MOSFET disconnects the amplifier’s outputs from the wiring harness in response to a high-voltage condition on either output. The MOSFETs, Q1A and Q1B, are normally on; zener diode D4 and its bias components drive the MOSFETs’ gates to approximately 11V. Dual diode D3 provides a diode-OR connection to the dc voltage on each output, thereby producing a voltage that controls the output of shunt regulator IC2. The circuitry protects IC1, a 1.4W Class AB amplifier suitable for audible warnings and indications for the automotive electronics.

Guards Amplifier Outputs Against Over-voltage Schematic

Figure 1 : This output circuit provides continuose protection against overvoltge faults

During normal operation, the amplifier outputs’ dc components are at one-half of the VCC supply—2.5V in this case, for which VCC is 5V. The 11V gate drive fully enhances the MOSFETs, and the shunt-regulator output is off because its feedback input, Pin 5, is below its internal 0.6V threshold. If either output exceeds 5V, current flows through D3 into the R5/R6 divider, pulling the feedback terminal above its threshold. The shunt-regulator output then pulls the MOSFET-gate voltage from 11V almost to ground, which blocks high voltage from the amplifier by turning off the MOSFETs. The MOSFETs easily withstand the continuous output voltage, and the circuit returns to normal operation when you remove the short. Because the circuit does not respond instantaneously, zener diodes D1 and D2 provide protection at the beginning of a fault condition.

Figure 2. In Figure 1, one of U1's two audio outputs (top trace) is protected when its external terminal accidentally contacts an 18V supply voltage (2nd trace).

The waveforms of Figure 2 represent an operating circuit. One of the amplifier’s outputs (Trace 1) is a 1-kHz sine wave biased at a dc voltage of 2.5V. Trace 2 is the signal on the wire harness. It also starts as a 1-kHz sine wave biased at a 2.5V-dc voltage, but, at 200 µsec, it shorts to an 18V supply. Trace 3 is the shunt regulator’s output, initially biased at 11V but pulled to ground in response to the overvoltage condition. Trace 4 is current in the wire harness. Initially a sine wave, this current drops to zero in response to the overvoltage condition. 

The components in Figure 1 optimize this circuit for 5V operation. For other voltages, you can adjust the R5/R6 resistor values. The shunt regulator must be able to function in saturation and, therefore, requires a separate supply pin in addition to the shunt output pin. The circuit repeatedly withstands 28V shorts without damage.

Source : www.maxim-ic.com

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Stereo Power Amplifier Using IC 7905

79xx is a widely known series of low-cost, fixed-negative-voltage regulators. These integrated circuits are available with output current of 100-150 mA (L series), 0.4-0.5A (M series), up to 1A (standard series), etc. They can be used in many applications other than regulators, audio power amplifier being one of them.  As shown in the circuit diagram, a simple stereo audio amplifier is built around two 7905 negative-voltage regulators (IC1 and IC2) and a few discrete components. The 7905 IC (a -5V regulator) used here is readily available. However, the circuit will also work with other 79XX regulators if appropriate power supply is used. Both channels shown in the diagram are identical. Hence the description below is only for the first channel. The quality of the output signal is within acceptable limits. 

Circuit diagram :

Stereo Power Amplifier Circuit Diagram

 

Regulator IC 7905 works as an amplifier for the voltages applied to common pin2 (Ground or GND). The minimal voltage drop over the standard 7905 is around 2V and it depends on the output current. Feedback resistors in the IC set the gain of the channel internally. The amplifier is a class-A audio amplifier. The regulator IC produces the negative output signal. 

Resistor R3 provides the positive signal. It limits the maximum output current of the regulator during the negative half period of the amplified sinusoidal signal. The minimal applicable value of R3 for the regulator 7905 is 8.2 to 10 ohms per 5W.  Optimisation of the value of R3 depends on the output voltage of the regulator, negative power supply (–5V) and load resistance of loudspeaker (LS1). If the required output current for LS1 is below 100 mA, the value of resistor R3 can be 33 to 51 ohms per watt. 

Normally, the load resistance of the loudspeaker should be higher than of R3 in order to obtain a large peak-to-peak amplitude. But this can be neglected in order to obtain lower power dissipation on R3 and the IC. The circuit works with any load resistance (R3 in parallel with LS1 as the load) under the condition that the regulator is not overloaded with current and power dissipation. However, it is preferable to use a loudspeaker with a high resistance (8 ohms, 16 ohms or more). The amplifier works well with low-impedance headphones having a resistance of 24 to 32 ohms. The voltage difference between the ground pin of 7905 and the output pin is fixed internally. 

The input resistance of the amplifier is relatively low and depends on potentiometer VR1 and input resistance of the ground pin. Practically, any stereo output capable of driving 24- or 32-ohm headphones and loudspeakers can drive the input of the stereo amplifier with 7905. If VR1 is removed, the amplifier will still work but there will be more distortion. Therefore potentiometer VR1 is used to provide sufficient variable audio signal.  The values of output capacitors C10 and C11 are usually between 0.1 µF and 1 µF. A small resistance can be connected in series with them if needed. S2 is the on/off switch. Switch S1 is for mono/stereo selection. When switch S1 is closed, the amplifier works as a two-way mono amplifier. If S1 is open, the amplifier works as a stereo amplifier. 

The circuit is powered by a 12V battery. The positive terminal of the battery is the common node. The negative terminal is connected to pin 2 of IC1, which is the –12V supply line. The maximum operating voltage can be up to –35V. If no input signal is applied, the DC voltage on the output of the regulator 7905 should be around –5V, which depends to some extent on the value of VR1. The maximum output current of 7905 can be up to 1A and the maximum power dissipation is up to 15W. IC 7905 has internal thermal protection. 

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Fix the stereo female jack on the front panel and speaker to the rear side of the cabinet, and the 12V battery inside the cabinet. Fix LED1 and switches S1 and S2 too on the front panel of the cabinet. Mount the regulator IC 7905 on a heat-sink with thermal resistance below 15°C/W. The metallic part on the case is internally connected with the input pin of the regulator.

Author : Petre tzv. Petrov

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Using a single 7812 IC - 12 Volt 30 Amp Circuit Diagram

This is the Using a single 7812 IC - 12 Volt 30 Amp Circuit Diagram simple project. Using a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps.

Notes:

The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) so that the regulator can maintain its output. If a transformer is used, then the rectifier diodes must be capable of passing a very high peak forward current, typically 100amps or more. The 7812 IC will only pass 1 amp or less of the output current, the remainder being supplied by the outboard pass transistors. 

As the circuit is designed to handle loads of up to 30 amps, then six TIP2955 are wired in parallel to meet this demand. The dissipation in each power transistor is one sixth of the total load, but adequate heat sinking is still required. Maximum load current will generate maximum dissipation, so a very large heat sink is required. In considering a heat sink, it may be a good idea to look for either a fan or water cooled heat sink. In the event that the power transistors should fail, then the regulator would have to supply full load current and would fail with catastrophic results. A 1 amp fuse in the regulators output prevents a safeguard. The 400mohm load is for test purposes only and should not be included in the final circuit.

 Using a single 7812 IC - 12 Volt 30 Amp Circuit Diagram 1

 Using a single 7812 IC - 12 Volt 30 Amp Circuit Diagram 2

Calculations:
This circuit is a fine example of Kirchoff's current and voltage laws. To summarise, the sum of the currents entering a junction, must equal the current leaving the junction, and the voltages around a loop must equal zero. For example, in the diagram above, the input voltage is 24 volts. 4 volts is dropped across R7 and 20 volts across the regulator input, 24 -4 -20 =0. At the output :- the total load current is 30 amps, the regulator supplies 0.866 A and the 6 transistors 4.855 Amp each , 30 = 6 * 4.855 + 0.866. Each power transistor contributes around 4.86 A to the load. The base current is about 138 mA per transistor. A DC current gain of 35 at a collector current of 6 amp is required. 

This is well within the limits of the TIP2955. Resistors R1 to R6 are included for stability and prevent current swamping as the manufacturing tolerances of dc current gain will be different for each transistor. Resistor R7 is 100 ohms and develops 4 Volts with maximun load. Power dissipation is hence (4^2)/200 or about 160 mW. I recommend using a 0.5 Watt resistor for R7. The input current to the regulator is fed via the emitter resistor and base emitter junctions of the power transistors. Once again using Kirchoff's current laws, the 871 mA regulator input current is derived from the base chain and the 40.3 mA flowing through the 100 Ohm resistor. 871.18 = 40.3 + 830. 88. The current from the regulator itself cannot be greater than the input current. As can be seen the regulator only draws about 5 mA and should run cold.[link]

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Camera Video Amplifier Circuit (Transistorized )

There are occasions  when you want to view your video clips taken in your digital camera on  your TV.You can do so by interfacing the camera video output to video input of your TV.But this times you cant connect directly as it needs some amplification before the signal reaches from camera to television

The video amplifier schematic circuit shown in the figure is a simple PAL video amp, expected to have a 3db bandwidth of 5.5MHz. You can connect your camera to TV through this circuit. So this is a low level transistorized video amplifier stage that accepts 1V (p-p) and outputs 2V(p-p) signal. 

Notes The circuit requires a 5V dc power supply

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10 to 14W Class A Audio Amplifier Circuit Diagram

This is the simple 10 to 14W Class A Audio Amplifier Circuit Diagram. I have built this amplifier and it does sound good. It requires a preamp as it hasn't got much gain. It requires big heat sinks and a large transformer and a great power supply and careful wiring, but in the end it is xtremely simple and it sounds very good. The zener diode rejects any ripple coming from the power supply, But you still only want a ripple of 10mV max. The ripple reaching the input is amplified, so the zener diode gets rid of that, but whatever ripple there is will still reach the power stage.

 10 to 14W Class A Audio Amplifier Circuit Diagram

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LM4910 Stereo Headphone Amplifier Circuit Diagram

LM4910 belonging to the Boomer series of National Semiconductors is an integrated stereo amplifier primarily intended for stereo headphone applications. The IC can be operated from 3.3V ans its can deliver 0.35mW output power into a 32 ohm load. The LM4910 has very low distortion ( less than 1%) and the shutdown current is less than 1uA. This low shut down current makes it suitable for battery operated applications. The IC is so designed that there is no need of the output coupling capacitors, half supply by-pass capacitors and bootstrap capacitors. Other features of the IC are turn ON/OFF click elimination, externally programmable gain etc.

Circuit diagram of the LM4910 stereo headphone amplifier is shown above.C1 and C2 are the input DC decoupling capacitors for the left and right input channels. R1 and R2 are the respective input resistors. R3 is the feed back resistor for left channel while R4 is the feed back resistor for the right channel. C3 is the power supply filter capacitor. The feedback resistors also sets the closed loop gain in conjunction with the corresponding input resistors.

Notes.

1. The IC is available only in SMD packages and care must be taken while soldering.
2. The circuit can be powered from anything between 2.2V to 5V DC.
3. The load can be a 32 ohm headphone.
4. Absolute maximum supply voltage is 6V and anything above it will destroy the IC.
5. A logic low voltage at the shutdown pins shut downs the IC and a logic high voltage at the same pin activates the IC.

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STK4050 Audio Amplifier with 200W Output

The project is based around the hybrid integrated circuit STK4050 manufactured by Sanyo to build a low noise mono audio amplifier with complete high quality. The project has a maximum output power of 200W while incorporating a volume control. The power supply used in the circuit is an on-board type and because of this, only a center tapped transformer is needed for the powering of the circuit. The sound has a very good quality and it can be proven when used in home theaters, in computers, and other audio equipments which can also be used as subwoofer amplifier. For thin-type audio sets, it can be considered as a compact package.

The heat generated in thin-type audio sets is being dispersed easily with a good heatsink design. There may be case where a shock noise may be encountered especially during switch ON and switch OFF. This can be reduced by providing a constant current circuit. The design of the circuit can be tailored for reducing occurrence of thermal shutdown, short circuit protection for loads, shock noise muting from external power supply. The load resistance should have 8 Ohms value with 55K Ohms input impedance.

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44 Watt Mobile Car Stereo Amplifier Circuit Diagram

Using a mobile phone while driving is dangerous. It is also against the law. However, you can use your mobile phone as a powerful music player with the help of a stereo power amplifier. This does away with the need of a sophisticated in-dash car music system. Most mobile phones have a music player that offers a number of features including preset/manual sound equalisers. They have standard 3.5mm stereo sockets that allow music to be played through standard stereo headphones/sound amplifiers. Nokia 2700 classic is an example.




A car audio amplifier with 3.5mm socket can be designed and simply connected to the mobile phone output via a shielded cable with suitable connectors/jacks (readymade 3.5mm male-to-male connector cable is a good alternative). Fig. 1 shows the circuit of car stereo player. It is built around popular single-chip audio power amplifier TDA1554Q (IC1). The TDA1554Q is an integrated class-B power amplifier in a 17-lead single-in-line (SIL) plastic power package.

Fig. 1: Circuit of mobile car stereo player

IC TDA1554Q contains four 11W identical amplifiers with differential input stages (two inverting and two non-inverting) and can be used for single-ended or bridge applications. The gain of each amplifier is fixed at 20 dB. Here it is configured as two 22W stereo bridge amplifiers. The amplifier is powered from the 12V car battery through RCA socket J2. Diode D1 protects against wrong-polarity connection. LED1 indicates the power status.

Connect stereo sound signal from the 3.5mm headset socket of the mobile phone to audio input socket J1. When you play the music from your mobile, IC1 amplifies the input. The output of IC1 is fed to speakers LS1 and LS2 fitted at a suitable place in your car. Electrolytic capacitor C5 connected between pin 4 of IC1 and GND improves the supply-voltage ripple rejection. Components R2 and C4 connected at mute/standby pin (pin 14) of IC1 eliminate the switch on/off plop. The circuit is quite compact. A good-quality heat-sink assembly is crucial for IC1. Fig. 2 shows the stereo socket and stereo jack.

Fig. 2: (a) 3.5mm stereo socket and (b) 3.5mm stereo jack

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Small dimensions of the power amplifier make it suitable for being enclosed in a plastic (ABS) case with vent holes. Signal input socket, speaker output terminals, on/off switch, indicator, fuse holder and power supply socket are best located on the front panel of the enclosure as shown in Fig. 3. Link

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Electric Guitar Violin Preamplifier Circuit Diagram

Magnetic pick-ups in musical instruments have a relatively high output impedance. This can result in a reduction in treble response when connected via a long cable run or to equipment with a low input impedance. This preamplifier provides a high input impedance and a low impedance output, solving both issues. It has adjustable voltage gain and can run off a battery or DC plugpack. The input signal is AC-coupled to the non-inverting input of IC1a, part of a TL074 quad op amp. This has JFET input transistors and the input impedance is set by a 330kΩ bias resistor which also sets the DC level at this input to half supply (Vcc/2). This is generated by a voltage divider comprising two 10kΩ resistors and bypassed by a 47µF capacitor to reject noise and hum.

Electric Guitar Violin Preamplifier Circuit Diagram





IC1a is configured as a non-inverting amplifier with a gain of between 2 and 20, depending on the setting of VR1. IC1a’s output is fed to VR2 via a 22µF capacitor, allowing the output volume to be set. The audio then passes to the non-inverting inputs of the remaining three op amps (IC1b-IC1d) which are connected in parallel to provide a low output impedance; it will drive a load impedance as low as 600Ω. The 100Ω resistors in series with the outputs provide short-circuit protection for the op amps and also prevent large currents from flowing between the outputs in case they have slightly different offset voltages.

The buffered signal is then AC-coupled to two output connectors using 47µF electrolytic capacitors. For Output 1, a 47kΩ resistor sets the output DC level to ground and a 220Ω series resistor provides further short-circuit protection. Output 2 is similar but includes another potentiometer (VR3) to allow its level to be set individually. Note that this means the impedance of Output 2 can be high (up to 2.5kΩ depending on the position of VR3’s wiper). The total harmonic distortion of this circuit is typically less than 0.01% with the gain set to six. If a TL064 is used instead of a TL074, the current drain will decrease but there will be more noise at the output. Finally, the input imped

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Low Distortion Audio Amplifier Circuit Diagram

This is an unusual circuit for an ultra-low distortion power amp. According to my original notes the circuit is dated January 1977 so the circuit is not exactly modern but it is still sufficiently different to be interesting. The circuit was designed and sold as a card by a purveyor of surplus components but, even using mostly manufacturer's rejected transistors, we managed to get about 0.02% total harmonic distortion at 30 watts with a ±25v power supply into 8 ohms.: no bad figure even in these days of MOSFET and ICs. In 1977 anything below 0.1% was considered excellent. And this figure was pretty repeatable without doing much selection. 

The problem of course is that since I haven't touched this amplifier for many a year I have absolutely no idea what modern transistor types one should use for it but they are not critical: output transistors and drivers need to be the correct type but the other transistors can be small signal types - as long as they can handle the full voltage between + and - supplies. 

Tr1 and Tr2 are a long-tailed pair (LTP to save typing). It is quite common to have a LTP in an audio amp but this is different: this is a complimentary LTP. As far as I am aware no one else had used a complimentary LTP at the time, though I have since seen it used in one other circuit. So I guess the circuit is unique to the author. One of the things that limits the performance of a conventional LTP is that the tail source loads the common emitters. In a complementary LTP this can't happen as there is no tail current source so that all the current of one transistor has to flow through the other. 

Tr2's collector current flows into D1 and D2 which develop a voltage: this is used to bias Tr8 as a constant current source for Tr4's collector. The fact that Tr4 is working at a constant current defines its base-emitter voltage which must be developed across R4. This defines a current in R4 and this is the current that the LTP must operate at - so the ring of four transistors (Tr1, 2, 3, & 4) is self biasing and all transistors work at their best with minimum unwanted loads and biasing detracting from the performance. Tr4 is actually one of the most critical transistors: in the original circuit it was selected for Vce greater than 75v. Most Texas BC212s passed easily. Lower voltage transistors caused an increase in distortion level. 

There is always a down side to any circuit: in the conventional LTP the base-emitter voltages tend to cancel each other out. In the complimentary LTP they add so there is a drop of about 1.2v between the two bases: this must be cancelled in the biasing chain and, since this circuit was designed for operation over a wide range of supply voltage, I had to be a little clever. Because of the constant current operation of the LTP and the constant voltage drop across D1 & D2, there is also a constant voltage across R14. This drop is used to lift up the bottom of the biasing chain (R1 and R11) so that the output sits at around half supply voltage, over a wider supply range. 

D3 and D4 develop a bias voltage so that the output transistors are at the correct point, slightly conducting, to minimise crossover distortion. 

The output transistors are complimentary (the original design used MJE2011 and MJE2021) and are driven by complimentary drivers: PNP driving NPN and vice versa. This arrangement is not only pleasingly symmetrical but gives better performance that the more common Darlington arrangement - the full gain of all the transistors is used and there is more internal feedback and less voltage drop. 

The output current is monitored in the two resistors R7 and R22 (180 milliohms). The current limiting is unusual in that it works inside the input ring at an earlier stage than normal. This has an advantage that the current limiting transistors do not load the drive circuitry - which will introduce distortion. The slight down side is that there may be a slight tendency to oscillation when in current limit. R3 and R14 are necessary to restrict the current availability when the current limit engages. R5 and R19 are present to make the current limit vary with the voltage across the power transistors to avoid the second breakdown region of power transistors. 

The points shown connecting terminals 1-2 and 6-7 are 'scratch-through tracks'. 1 and 2 are the power and signal earths: to keep distortion in a stereo system to a minimum the currents in these must never share the same path so in a stereo system four earth wires are run to the system's common earth point - a 'spider' common earth - and this means breaking the link. The link between 6 & 7 is in the feedback path and there are times when this can usefully be broken - one 'cheapskate' was to fit a tone control circuit here (see below). It works fine but is a bit of an insult to such a low-distortion design!. A third break point is in the collector of Tr2. Breaking this shuts down the amplifier completely and safely. Is a thermal switch is to be fitted, this is the place. 

Overall negative feedback is in two parts: D.c. is fed back via R13: there is 100% d.c. feedback. A.c. feedback is via R12 and R17. Note the output capacitor is inside this feedback loop (speaker connects between terminal 5 and negative) which extends the low frequency response. 

Another feature is the accessibility of both ends of the output coupling capacitor: being designed for a junk shop, they didn't want to use expensive capacitors! So for extra bass performance an additional capacitor can easily be connected. 

The circuit can also be driven as a low input impedance: break 6-7, short pin 8 to C4's positive and apply input to pin 6. In this mode the input distortion is actually better: my original notes show as low as 0.01%!

When building a low-distortion amplifier, layout is vital. In fact to get distortion around 0.02% requires a lot of skill and experience. The problem is that the current in the output stage alternates between the two power transistors so is a 'rectified' version of the input. Now there is no such thing as a 'wire'. Any real piece of wire or copper track is a resistor with associated inductance and capacitance. If the high current, rectified output signal mixes in the same 'piece of wire' with the input signal the distortion in the rectified output current will feed into the input and cause the overall distortion to rocket. This is something which cannot properly be taught but has to be experienced. A skilled audio engineer will spend his lifetime learning about it. 

Source by : streampowers

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22 Watt Stereo Amplifier Circuit Diagram

This is the simple 22 Watt Stereo Amplifier Circuit Diagram. This circuit is very basic to build and puts out great power for your car or home. Keep all leads as short as possible.

 22 Watt Stereo Amplifier Circuit Diagram

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10W Stereo Audio Amplifier Using TDA2009A

This is a schematic of a 10W stereo audio amplifier using TDA2009A amplifier IC. TDA2009A is a good IC provides quality sound. It has built in features like output current protection and thermal protection etc. The circuit can be operate between 8 to 24V DC with 1 to 2 amphere.

10W Stereo Audio Amplifier Circuit Diagram :

If you want to operate this 10 watt amplifier circuit with watt amplifier circuit with mains supply then use a filtered and stable power supply to reduce mains hum. 10 watt out put power can be obtained by providing 20V 1.5A to the circuit. Use good and thick heatsink with the IC. 

Source By : Circuitsstream

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20 Watt Power Amplifier Circuit Diagram

This IC chip was designed specifically for use in power boosting applications in automobiles. It is self protecting against short circuits and thermal problems. In the bridge configuration shown it will deliver 20 watts of power into a 2 ohm speaker operating at 14.4 volts.

20 Watt Power Amplifier Circuit Diagram

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Single-Supply Instrumentation Amplifier Circuit Diagram

The OP284 is a low noise dual op amp with a bandwidth of 4MHz and rail-to-rail input/output operation. These properties make it ideal for low supply voltage applications such as in a two op amp instrumentation amplifier as shown in the diagram. The circuit uses the classic two op amp instrumentation topology with four resistors to set the gain. The transfer equation of the circuit is identical to that of a non-inverting amplifier. Resistors R2 and R3 should be closely matched to each other as well as to resistors (R1+P1) and R4 to ensure good common-mode rejection (CMR) performance. It is advisable to use resistor networks for R2 an and R3, because these exhibit the necessary relative tolerance matching for good performance.

Potentiometer P1 is used for optimum d.c. CMR adjustment, and capacitor C1 is used to optimize a.c. CMR. With circuit values as shown, circuit CMR is better than 80 dB over the frequency range of 20 Hz to 20 kHz. Circuit referred-to-input (RTI) noise in the 0.1 Hz to 10 Hz band is exemplary at 0.45 µVpp. Resistors R5 and R6 protect the inputs of the op amps against over-voltages. Capacitor C2 may be included to limit the bandwidth. Its value should be adjusted depending on the required closed-loop bandwidth of the circuit. The R4-C2 time constant creates a pole at a frequency, f3dB, equal to f3dB=1/2πR4C2. With a value of C2 of 12 pF, the bandwidth is about 500 kHz. The amplifier draws a current of about 2mA. 

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Low Power Wireless Audio Power Amplifier

Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and Loud Speaker. In place of a pair of wires, it uses invisible infra-red light to transmit audio signals from TV to Loud speakers, Without using any lens a range of up to 6 meters is possible. Range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers.

Transmitter's operation:

IR transmitter uses two-stage transistor amplifier to drive two series-connected IR LEDs. An audio output transformer (T1) is used (in reverse) to couple audio output from TV to the IR transmitter. Transistors Q1 and Q2 amplify the audio signals received from TV through the audio transformer. Low impedance output windings (lower gauge or thicker wires) are used for connection to TV side while high-impedance windings are connected to IR transmitter. This IR transmitter can be powered from a 9V mains adapter or a 9V battery. Red LED (D1) in transmitter circuit functions as a Zener diode (0.65V) as well as supply-on indicator.

Transmitter diagram:

Wireless Audio Power Amplifier Transmitter Circuit Diagram

Receiver's operation:

IR receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 (Q3) and some discrete components. The sound generated by TV set is transmitted through IR LEDs, received by phototransistor Q3 and fed to pin 2 of IC µA741 (IC1). Its gain can be varied using potmeter P2. The output of IC µA741 is fed to IC LM386 (IC2) via capacitor (C7) and potmeter P3. The sound produced is heard through the receiver’s loudspeaker. Potmeter P3 is used to control the volume of loudspeaker SPKR (8-ohm, 1W).

Receiver diagram:

Wireless Audio Power Amplifier Transmitter Circuit Diagram

Parts:

P1 = 10K
P3 = 10K
P2 = 1M

R1 = 4.7K
R2 = 22K
R3 = 100R
R4 = 10R-1W
R5 = 10K
R6 = 10K
R7 = 15K
R8 = 15K
R9 = 100K
R10 = 680R-1W
R11 = 1K
R12 = 10R-1W

C1 = 220uF-25V
C2 = 220uF-25V
C3 = 10uF-25V
C4 = 220uF-25V
C5 = 220uF-25V
C6 = 100nF-63V
C7 = 100nF-63V
C8 = 100nF-63V
C9 = 100nF-63V

D1 = Red LED
D2 = IR LEDs
D3 = IR LEDs

Q1 = BC547
Q2 = BD140
Q3 = L14F1

IC1 = uA741 Opamp
IC2 = LM386

J1 = Audio input Jack
T1 = Audio Transformer
SPKR = 1W-8ohm

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5.8 Watt Audio Power Amplifier Circuit Diagram

This circuit use TA7222AP to amplifiers audio signal .The price only $0.99 and can provide 5.8 watt with Muting Control.Power supply can use for 8-12Vdc it is a good idea to use for car audio power amp , coin-op machine game, security system etc. link

Fig 1. TA7222AP pin out

Pin	Name	Description
1	Vcc	Supply Voltage
2	RR	Ripple Reject
3	MC	Muting control
4	OP	AF Signal Input
5	FB	FB Filter
6	GA	Gain adjust
7	GND	Ground
8	GND	Ground
9	OP	AF Output
10	BS	BootStrap

Fig 2. schematic for 5.8 watt audio power amplifier

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Balanced Microphone Amplifier Circuit Diagram

We published a design for a stereo microphone preamplifier with balanced inputs and a phantom power supply. The heart of this circuit was a special Analog Devices IC, the SSM2017. Unfortunately, this IC has been discontinued. In its place, the company recommends using the pin-compatible AMP02 from its current product line. However, and again unfortunately, the specifications of this opamp make it considerably less suitable for use as a microphone amplifier. By contrast, Texas Instruments (in their Burr Brown product line) offer an integrated instrumentation amplifier (type 1NA217) that has better specifications for this purpose.


Incidentally, this IC is also recommended as a replacement for the SSM2017. It features internal current feedback, which ensures low distortion (THD + noise is 0.004 % at a gain of 100), low input-stage noise (1.3 nV/√Hz) and wide bandwidth (800 kHz at a gain of 100). The supply voltage range is ±4.5 V to ±18 V. The maximum current consumption of the 1NA217 is ±12 mA. The gain is determined by only one resistance, which is the resistance between pins 1 and 8 of the IC. The circuit shown here is a standard application circuit for this instrumentation amplifier. R1 and R2 provide a separate phantom supply for the microphone connected to the amplifier (this is primarily used with professional equipment).

Balanced Microphone Amplifier Circuit Diagram

This supply can be enabled or disabled using S1. C1 and C2 prevent the phantom voltage from appearing at the inputs of the amplifier. If a phantom supply is not used, R1 and R2 can be omitted, and it is then better to use MKT types for C1 and C2. Diodes D1–D4 are included to protect the inputs of the 1NA217 against high input voltages (such as may occur when the phantom supply is switched on). R4 and R5 hold the bias voltage of the input stage at ground potential. The gain is made variable by including potentiometer P1 in series with R6. A special reverse log-taper audio potentiometer is recommended for P1 to allow the volume adjustment to follow a linear dB scale.

The input bias currents (12 µA maximum!) produce an offset voltage across the input resistors (R4 and R5). Depending on the gain, this can lead to a rather large offset voltage at the output (several volts). If you want to avoid using a decoupling capacitor at the output, an active offset compensation circuit provides a solution. In this circuit, a FET-input opamp with a low input offset (an OPA137) is used for this purpose. It acts as an integrator that provides reverse feedback to pin 5, so the DC output level is always held to 0 V. This opamp is not in the audio signal path, so it does not affect signal quality. Naturally, other types of low-offset opamps could also be used for this purpose. The current consumption of the circuit is primarily determined by the quiescent current of IC1, since the OPA137 consumes only 0.22 mA.

Author: T. Giesberts
Copyright: Elektor Electronics

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AB Transistor Audio Power Amplifier Circuit Diagram

This is a class AB transistor power amplifier. It is a simple amplifier to build, uses standard parts and is stable and reliable.  The entire circuit utilizes commonly available components and may be simply built over a general-purpose board. But this amplifier has very good sound quality.

There are eleven transistors, including four in the output stage. Q1 and Q2 transistor must be between 3 and 5  amperes power transistors. Q4 and Q5 must be between 100mA and 500mA driver transistors. Other transistors are 10mA small driver transistors. Q1, Q4 and Q2, Q5 are complementary pairs, they make complementary darlington pairs.

PART LIST
R1	1.5KΩ ¼W
R2	150Ω ¼W
R3	1KΩ ¼W
R4	0.22Ω 2W
R5	0.22Ω 2W
R6	39KΩ ¼W
R7	1KΩ ¼W
R8	120Ω ¼W
R9	6.8KΩ ¼W
R10	6.8KΩ ¼W
R11	47KΩ ¼W
R12	47KΩ ¼W
R13	2.2KΩ ¼W
R14	180KΩ ¼W
R15	18KΩ ¼W
C1	22pF Ceramic
C2	4.7µF 16V
C3	1000µF 25V
C4	100µF 25V
D1	1N4148
D2	1N4148
Q1	2SD313
Q2	2SB507
Q3	2SA733
Q4	2SB560
Q5	2SD400
Q6, Q7, Q8, Q9, Q10	2SA733
Q11	2SD400
LS1	4Ω 20W SPEAKER

Power output of the amplifier

Supply voltage (Vs)	= 20V
Speaker impedance (R)	= 4Ω
Peak to peak voltage (Vpp)	= 20-2 =18V
Peak voltage	= 9V
Maximum output (Pmax)	= 9V2/2R
	= 81/8
	= 10W

10W is much enough for the day today home usage.
Amplification of this amplifier (A)

A	= R6/R13+1
	= 39KΩ/2.2KΩ+1
	= 18

Volume control can be added to the circuit by connecting a 10KΩ  POT in series to the input of the amplifier.

Q1 and Q2 must be kept sufficiently cool, so it is mounted on a suitable heat sink. If you used single heat sink please use insulation between transistors and heat sink.

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10W Small Audio Amplifier Circuit Diagram

You can use this powerfull amplifier in any small audio project. It is very small (6.5 x 4.5 cm).It outputs 10W and uses a 9V battery.

Component

 

PCB

Componets List

R1 : 6 Ohm

R2 : 220 Ohm

R3 : nothing

R4 : 10 KOhm pontesiometer

C1 : 2200 uF / 25V

C2 : 470 uF / 16V

C3 : 470 nF / 63V

C4 : 100 nF

C5 : nothing

C6 : nothing

IC1 : TDA 2003

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