65W Power Amplifier Circuits with HEXFET

65W Power Amplifier Circuits with HEXFET

A average ability amplifier that is characterized by a lot of acceptable complete quality, but accompanying is actual simple in the construction. Him uses, abundant time in my alive loudspeakers. In his achievement date abide the actual acceptable FET transistors, technology HEXFET, transistor which are controlled by voltage and no by accepted as the classically bipolar transistors. The ambit has balanced designing, absolute appropriately the harmonic baloney problem.

All the transistors that are acclimated in the ambit are simple and they abide in big clearings in the market. The pairs of cogwheel amplifiers Q1-2 and Q3-4 should be akin amid them and abreast the one in the other. Appropriately you can buy abundant transistors of types BC550C and BC560C, and with a multimeter you bout amid them creating pairs with aforementioned characteristics, ensuring appropriately compatible behavior in the temperature changes etc. Networks RC from the R7/C3 and R12/C4 abatement the bandwidth of cogwheel amplifiers and ability amplifier in the 6.5MHZ. Resistors R8-9-10-11 action as bounded acknowledgment in the cogwheel amplifiers convalescent the linearity. The cogwheel amplifiers are supplied with connected accepted from him accepted sources Q5 and Q6. The bent of accepted sources becomes from the aggregate of diodes LED D1, D2 and R20.

This becomes because the aggregate transistor/LED ensures big thermic stability, for this acumen should they are in actual abreast ambit [1]. With the TR1 trimmer we adapt the bent accepted of achievement ability stage. For this acumen Q8 should acquisition itself on the heatsink so that it ensures thermic adherence in the bias, so that it does not change with the temperature changes. The resistors R32-33 appearance a bounded acknowledgment bronchus in the achievement stage, because this functions as voltage amplifier.

With the TR1, R3-4, C14 we adapt the amplifier achievement DC account voltage, abreast in the zero. The transistors Q8-10-11-12-13, [Fig.1] should are placed on heatsink, abacus amid the transistors and the heatsink of acceptable affection leaves mica and ointment. Inductor L1 is constituted by 6 coils of cloistral cupreous wire of bore 1.5mm, with centralized inductor bore of 16mm

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Guitar Amplifier Circuit Diagram 100W

Guitar Amplifier Circuit Diagram 100W

The ability amp lath has remained banausic back it was aboriginal appear in 2002. It absolutely isn’t broken, so there’s no acumen to fix it. The photo beneath shows a absolutely accumulated lath (available as apparent as M27). Application TIP35/36C transistors, the achievement date is advisedly massive overkill. This ensures believability beneath the best backbreaking date conditions. No amplifier can be fabricated allowed from everything, but this does appear close.

The ability amp (like the antecedent version) is about based on the 60 Watt amp ahead appear (Project 03), but it has added accretion to bout the preamp. Other modifications accommodate the abbreviate ambit aegis – the two little groups of apparatus abutting to the bent diodes (D2 and D3). This new adaptation is not massively altered from the original, but has adjustable bias, and is advised to accommodate a “constant current” (i.e. aerial impedance) achievement to the speakers – this is accomplished application R23 and R26. Note that with this arrangement, the accretion will change depending on the amount impedance, with lower impedances giving lower ability amp gain. This is not a problem, so may cautiously be ignored.

Should the achievement be shorted, the connected accepted achievement appropriate will accommodate an antecedent akin of protection, but is not absolutely foolproof. The abbreviate ambit aegis will absolute the achievement accepted to a almost safe level, but a abiding abbreviate will account the achievement transistors to abort if the amp is apprenticed hard. The aegis is advised not to accomplish beneath accustomed conditions, but will absolute the aiguille achievement accepted to about 8.5 Amps. Beneath these conditions, the centralized fuses (or the achievement transistors) will apparently draft if the abbreviate is not detected in time.

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MP3 Car Amplifier Schematic Circuits 150W

MP3 Car Amplifier Schematic Circuits 150W

These accessories are low cost, aerial speed, bifold JFET ascribe operational amplifiers with an internally akin ascribe account voltage (BI-FET II technology). They crave low accumulation accepted yet advance a ample accretion bandage amplitude artefact and fast bulk rate. In addition, able-bodied akin aerial voltage JFET ascribe accessories accommodate actual low ascribe bent and account currents. The LF353 is pin accordant with the accepted LM1558 acceptance designers to anon advancement e the all-embracing achievement of absolute LM1558 and LM358 designs. These amplifiers may be acclimated in applications such as aerial acceleration integrators, fast D/A converters, sample and authority circuits and abounding added circuits acute low ascribe account voltage, low ascribe bent current, aerial ascribe impedance, aerial bulk amount and advanced bandwidth. The accessories additionally display low babble and account voltage drift. (National Semiconductor

Internally trimmed offset voltage: 10 mV
Low input bias current: 50pA
Low input noise voltage: 25 nV
Low input noise current: 0.01 pA
Wide gain bandwidth: 4 MHz
High slew rate: 13 V/us
Low supply current: 3.6 m
High input impedance: 1012.
Low total harmonic distortion : <>

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Condenser Pre Amplifier LM 1458

This is a simple preamplifier circuit for electret condenser microphone.
using a LM1458 dual op amp IC. The circuit takes the audio signal rom the condenser microphone and amplifier it, so you can use the microphone as the input to some device which wouldn’t normally accept microphone level signals .

Schematic Circuit of Microphone Electret

Condenser Pre Amplifier



The circuit requires a 6-9 volt supply. Output of the microphone amplifier can be made variable by connecting a 10kΩ potentiometer . Circuit’s gain can be increased by men perbesar the value of 47K, depending on the input sensitivity of the main amplifier system. The microphone should be housed in a small round enclosure.
List componet of condenser pre-amp mic circuit

Q1,Q2    : LM1458 Op-Amp
R1,R2,R3 : 4.7k ohm resistor
R4, R5   : 10k ohm resistor
R6,R7    : 47k ohm resistor
C1,      : 0.22uF ceramic capacitor
C2       : 1uF ceramic capacitor

Absolute maximum ratings of LM 1458 IC

Supply Voltage               :  ±18V
Power Dissipation            : 400 mW
Differential Input Voltage   : ±30V
Input Voltage                : ±15V
Output Short-Circuit Duration: Continuous
Operating Temperature Range  : 0°C to +70°C
Storage Temperature Range    : −65°C to +150°C
Lead Temperature             :(Soldering, 10 sec.) 260°C

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1W BTL Audio Amplifier

The TDA8581(T) from Philips Semiconductors is a 1-watt Bridge Tied Load (BTL) audio power amplifier capable of delivering 1 watt output power into an 8-Wload at THD (total harmonic distortion) of 10% and using a 5V power supply.

The schematic shown here combines the functional diagram of the TDA8551 with its typical application circuit. The gain of the amplifier can be set by the digital volume control input. At the highest volume setting, the gain is 20 dB. Using the MODE pin the device can be switched to one of three modes: standby (MODE level between Vp and Vp–0.5 V), muted (MODE level between 1 V and Vp–1.4 V) or normal (MODE level less than 0.5 V). The TDA8551 is protected by an internal thermal shutdown protection mechanism. The total voltage loss for both MOS transistors in the complementary output stage is less than 1 V.

1 Watt BTL Audio Amplifier Circuit Diagram:

Using a 5-V supply and an 8-W loudspeaker, an output power of 1 watt can be delivered. The volume control has an attenuation range of between 0 dB and 80 dB in 64 steps set by the 3-state level at the UP/DOWN pin: floating: volume remains unchanged; negative pulses: decrease volume; positive pulses: increase volume Each pulse at he Up/DOWN pin causes a change in gain of 80/64 = 1.25 dB (typical value).

When the supply voltage is first connected, the attenuator is set to 40 dB (low volume), so the gain of the total amplifier is then –20 dB. Some positive pulses have to be applied to the UP/DOWN pin to achieve listening volume. The graph shows the THD as a function of output power. The maximum quiescent current consumption of the amplifier is specified at 10 mA, to which should be added the current resulting from the output offset voltage divided by the load impedance.

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Boomer Audio Power Amplifier Using LM4906

The well-known LM386 is an excellent choice for many designs requiring a small audio power amplifier (1-watt) in a single chip. However, the LM386 requires quite a few external parts including some electrolytic capacitors, which unfortunately add volume and cost to the circuit.

National Semiconductor recently introduced its Boomer® audio integrated circuits which were designed specifically to provide high quality audio while requiring a minimum amount of external components (in surface mount packaging only). The LM4906 is capable of delivering 1 watt of continuous average power to an 8-ohm load with less than 1% distortion (THD+N) from a +5 V power supply. The chip happily works with an external PSRR (Power Supply Rejection Ratio) bypass capacitor of just 1 µF minimum.

In addition, no output coupling capacitors or bootstrap capacitors are required which makes the LM4906 ideally suited for cellphone and other low voltage portable applications. The LM4906 features a low-power consumption shutdown mode (the part is enabled by pulling the SD pin high).

Additionally, an internal thermal shutdown protection mechanism is provided. The LM4906 also has an internal selectable gain of either 6 dB or 12 dB. A bridge amplifier design has a few distinct advantages over the single-ended configuration, as it provides differential drive to the load, thus doubling output swing for a specified supply voltage. Four times the output power is possible as compared to a single-ended amplifier under the same conditions (particularly when considering the low supply voltage of 5 to 6 volts).

Boomer Audio Power Amplifier Circuit Diagram:

When pushed for output power, the small SMD case has to be assisted in keeping a cool head. By adding copper foil, the thermal resistance of the application can be reduced from the free air value, resulting in higher PDMAX values without thermal shutdown protection circuitry being activated. Additional copper foil can be added to any of the leads connected to the LM4906. It is especially effective when connected to VDD, GND, and the output pins. A bridge configuration, such as the one used in LM4906, also creates a second advantage over single-ended amplifiers. Since the differential outputs, Vo1 and Vo2, are biased at half-supply, no net DC voltage exists across the load.

This eliminates the need for an output coupling capacitor which is required in a single supply, single-ended amplifier configuration. Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain sized capacitor is needed to couple in low frequencies without severe attenuation. But in many cases the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 100 Hz to 150 Hz. Thus, using a large input capacitor may not increase actual system performance. Also, by minimizing the capacitor size based on necessary low frequency response, turn-on pops can be minimized.

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Portable 9v Headphone Amplifier

High Quality One-IC unit, Low current consumption. After several requests by correspondents, the decision of designing a 9V powered Headphone Amplifier was finally taken. The main requirement was to power the circuit by means of a common, PP3 (transistor radio) alkaline battery. So, implementing a low current drawing circuit was absolutely necessary, though preserving a High Quality performance.

Portable 9v Headphone Amplifier Circuit Diagram

Parts:
P1 = 22K
R1 = 18K
R2 = 68K
R3 = 68K
R4 = 68K
R5 = 18K
R6 = 68K
C1 = 4.7uF-25v
C2 = 4.7uF-25v
C3 = 22pF
C4 = 220uF-25v
C5 = 220uF-25v
C6 = 4.7uF-25v
C7 = 22pF
C8 = 220uF-25v
J1 = 3.5mm Stereo Jack
B1 = 9V Alkaline Battery
IC1 = NE5532-34
SW1 = SPST Toggle Switch

The appearance of the 5534 low-noise op-amp at a reasonable price was much appreciated by audio designers. It is now difficult or impossible to design a discrete stage that has the performance of the 5534 without quite unacceptable complexity. 5534 op-amps are now available from several sources, in a conventional 8-pin d.i.l. format. This version is internally compensated for gains of three or more, but requires a small external capacitor (5-15pF) for unity-gain stability. The 5532 is a very convenient package of two 5534s in one 8-pin device with internal unity-gain compensation, as there are no spare pins.

The 5534/2 is a low-distortion, low-noise device, having also the ability to drive low-impedance loads to a full voltage swing while maintaining low distortion. Furthermore, it is fully output short-circuit proof. Therefore, this circuit was implemented with a single 5532 chip forming a pair of stereo, inverting amplifiers, having an ac gain of about 3.5 and capable of delivering up to 3.6V peak-to-peak into a 32 Ohm load (corresponding to 50mW RMS) at less than 0.025% total harmonic distortion (1kHz & 10kHz). If we consider that the mean current drawing at a power output of 15mW per channel is around 12-13mA (both channels driven), this Headphone Amplifier will become a must for many DIY enthusiasts needing a High Quality, High Performance portable device.

Technical data
Sensitivity:
    200mV RMS for 15.6mW RMS output
    350mV RMS for 50mW RMS output
Maximum undistorted output: 3.6V Peak-to-peak
Frequency response: flat from 40Hz to 20KHz; -2.3dB @ 20Hz
Total harmonic distortion @ 1KHz: <0.025% at all power outputs up to 50mW RMS
Total harmonic distortion @10KHz: <0.02% at all power outputs up to 50mW RMS
Total current drawing @ 9V supply (both channels driven):
    Standing current: 8.5mA
    Mean current drawing @ 15mW RMS per channel: 12mA
    Mean current drawing @ 35mW RMS per channel: 17mA

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Car Audio Amplifier Instalation Guide

Amplifier and speakers wiring. The amplifier does not always come with wire connection. You need a kit amp wiring harness sold separately. It is important to adjust the harness to the vehicle you have, to the right frequency and sound. The red wires (positive) is thicker than black (ground). A 12 -, 10 – or 8-gauge wire or lower is better sound quality.

Connecting the power cable and head unit. Disconnect the negative battery cable car, then the positive. Connect the red amplifier (positive) to the positive battery cable. Strip one end of the thread about half an inch and squeeze the cable connector U-Connect the positive terminal of the battery and tighten. Slide the other end through the firewall of your car, which is located towards the rear under the hood. Drag the interior and on the back of the torso. You may need to unscrew the bottom plate on each side and pull the seat back to move the thread. Black lead to an O-ring and screws for the metal of the cars to squeeze into the trunk.

Check if your head unit has suspended two AV, the ends of the women. If not, you have to buy one and have it installed. AV wire supplied with the kit must be long enough to reach from the amplifier in the trunk of the radio. Connect the ends of the red and white male to the female ends of the amplifier and the radio. Then connect the son of the subwoofer amplifier. Connect the negative terminal of the battery.

Turn the key to your car and listen to the radio at low volume. Not at full power crank. You get a distorted sound, or a speaker can blow the air. You will feel the vibration in the car audio system.

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LM377 Power amplifier schematic

Different places and use also requires a different power amplifier as well. For this time i gave a circuit schematic power amplifier based on LM377 ic that has similarities with the LM378 and LM1877. Power is smoothly small ouput is 2 X 2.5 Watt and the impedance 4 ohms. Use of this amplifier suitable for portable radio tuner that can be taken every where.

Component description :

Resistor
R1___________________2K
R2___________________2K
R3___________________1M
R4___________________1M

Capacitor
C1___________________4.7uF 50V
C2___________________4.7uF 50V
C3___________________100n
C4___________________100n
C5___________________470uF 50V
C6___________________470uF 50V

IC
IC1__________________LM377 , LM378 , LM1877

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High End Power Amplifier Wiring Circuit

As the causes of the heat sink mounting surface to approximately 6 mm from the edge of the circle are fixed, assuming that the amplifier circuits mounted directly on the rails. This means that the leads of the transistors must be folded twice, so they are positioned properly, without a permanent mechanical stress in transistors. For high output transistors, the first corner a little closer to the plastic packaging than expected (in the wide part), otherwise the son of the rails or not to strike. Another possibility, which has the disadvantage that it weakens the structure, it is to grind enough metal in appropriate locations, to provide sufficient clearance. We have consciously rejected that option.

Once you have taken on these details and transistors can be easily placed on the free flat heatsink with her son through the holes in the circuit you can use the locations of the holes on the back mark of the radiators. Of course you must do so before the transistors are soldered to the track but is according to the holes for the final determination of the amplification circuits made in the base plate. Once the output transistors and their driver were mounted on the heat sink and soldered to the boards, the bottom plate can be removed easily.

Be careful not too much force on the terminals of the transistors, if the plates are exposed in this way.

Power transistors T14 and T15 must be mounted on heatsink bs with insulators (mica discs), while the other three transistors (Til, T12 and T13) can be screwed directly onto the heat sink. Make sure you use thermal paste to all the transistors.

After all the holes for the remaining circuits, transformers, switches and lights (front) and the ventilation slots in the chassis, you can screw up everything and you install the wiring.

Use well-designed audio cable connected to the input of the amplifier boards on the terminals in the vicinity of the inputs on the board overdrive display. With the two ground terminals to the input jacks for connecting the housing to the grounds of the two channels. This will avoid creating loops. The inputs to the outputs of the amplifier are in the middle of the board control overdrive removed. The best way to connect, to use thin, flexible cable, to connect the output jacks.

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Mono Power Amplifier A1015 BD140 TIP2955

Typically audio amplifier stereo amplifier to a two amplifier. And if a mono amplifier is a single speaker. However this circuit command be present extended to the mono two loudspeaker.But not a equivalence or else serialization access.This makes it needless impedance of the speaker has altered.But will remain to utilize the spokeswoman as a replacement for of the resistance - Collection Peter (RC) of the transistor.The circuit can be alive prolonged to 2 loudspeaker itself.

Mono Power Amplifier - A1015, BD140 ,TIP2955 Circuit Diagram

What time raising the power supply circuit and the audio to input. the audio sign coupling to through the C1 and R1 to increase with the Q1.Which Q1 serves like the Regional Pre amp amplifier to power up to a one point.already conveyance it to Q2.Which Q2 is connected to emitter follower circuit.be active as a driver amplifier intimate section from the pre amp section provides added power to drive the Q3 perform. and Q3 motivation provide while a Regional Power amp amplifier output to the spokeswoman.The opinion of the audio intimate through the VR1 and R2 to enter the pin B of Q2.To control the stability of working instead of well brought-up.This circuit is an output of 40 milliwatts watts of distortion of the gesture rate is by the side of 0.1 percent.And frequency response from 15 Hz - 200 kHz.

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Mini Guitar Bass Amplifier Diagram Circuit

Output power: 6W into 4 Ohm load, FET input stage - Passive Tone Control
Tiny, portable Guitar Amplifiers are useful for practice on the go and in bedroom/living room environment. Usually, they can be battery powered and feature a headphone output. This project is formed by an FET input circuitry, featuring a High/Low sensitivity switch, followed by a passive Tone Control circuit suitable to Guitar or Bass. After the Volume control, a 6W IC power amplifier follows, powered by a 12-14V dc external supply Adaptor or from batteries, and driving a 4 Ohm 10 or 13cm (4"/5") diameter car loudspeaker. Private listening by means of headphones is also possible.

Circuit diagram:

Mini Guitar-Bass Amplifier Circuit Diagram

Parts:

P1______________1M Linear Potentiometer
P2____________100K Log Potentiometer
R1_____________68K 1/4W Resistor
R2____________470K 1/4W Resistor
R3______________2K7 1/4W Resistor
R4______________8K2 1/4W Resistor
R5____________680R 1/4W Resistor
R6____________220K 1/4W Resistor
R7_____________39R 1/4W Resistor
R8______________2R2 1/4W Resistor
R9____________220R 1/4W Resistor
R10_____________1R 1/4W Resistor
R11___________100R 1/2W Resistor
R12_____________1K5 1/4W Resistor
C1____________100pF 63V Polystyrene or Ceramic Capacitor
C2,C5,C9,C14__100nF 63V Polyester Capacitors
C3____________100µF 25V Electrolytic Capacitor
C4_____________47µF 25V Electrolytic Capacitor
C6______________4n7 63V Polyester Capacitor
C7____________470pF 63V Polystyrene or Ceramic Capacitor
C8______________2µ2 25V Electrolytic Capacitor
C10___________470µF 25V Electrolytic Capacitor
C11____________22nF 63V Polyester Capacitor
C12__________2200µF 25V Electrolytic Capacitor
C13__________1000µF 25V Electrolytic Capacitor
D1______________3mm red LED
Q1____________BF245 or 2N3819 General-purpose N-Channel FET
IC1_________TDA2003 10W Car Radio Audio Amplifier IC
SW1,SW2________SPST toggle or slide Switches
J1____________6.3mm Mono Jack socket
J2____________6.3mm Stereo Jack socket (switched)
J3_____________Mini DC Power Socket
SPKR__________4 Ohm Car Loudspeaker 100 or 130mm diameter

Notes:

• Connect the output Plug of a 12 - 14V dc 500mA Power Supply Adaptor to J3
• Please note that if the voltage supply will exceed 18V dc the IC will shut down automatically

Technical data:

Output power (1KHz sinewave):
6W RMS into 4 Ohm at 14.4V supply
Sensitivity:
50mV RMS input for full output
Frequency response:
25Hz to 20kHz -3dB with the cursor of P1 in center position
Total harmonic distortion:
0.05 - 4.5W RMS: 0.15% 6W RMS: 10%

Tone Control Frequency Response:

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2 x 22W BTL Car Audio Amplifier DA1553CQ

This is a 22 Watt car stereo audio amplifier. The circuit is based by a single IC TDA1553 with a few peripheral components, this IC hope against hope code name your stereo car audio classification. The IC TDA1553CQ contains 2×22 W amplifiers with differential input stages and can exist used in favor of connection applications.. The expansion of apiece amplifier is fixed by the side of 26 dB. The device is primarily residential for car broadcasting applications.

Circuit Diagram 2 x 22W-BTL Car Audio Amplifier Using DA1553CQ

Circuit Diagram 2 x 22W-BTL Car Audio Amplifier Using TDA1553CQ 

• The TDA1553CQ IC have got to be present fitted with adequately sized cook sinks.
• unite a 10K POT happening string with the input because volume control if you need. Not publicized in circuit diagram.
• employment 12V DC in favor of powering the circuit.

What time a diminutive-circuit to ground occurs, which forces a DC voltage across the loudspeaker of >= vs., a built-in protection circuit becomes full of life and limits the DC voltage across the loudspeaker to <= vs.. pin 12 detects the status of the protection circuit (e.g. meant for diagnostic purposes).

If slightly output is unfriendly-circuited to ground in the course of the side with mode, it becomes hopeless to switch the circuit to the mute otherwise operating condition. happening this event the supply current determination remain some degree of to a little milliamps.

Video Distribution Amplifier

With the amount of equipment during in entertainment centers at present the need to survive able to vary the profit of the audio otherwise capture on film sign is required. I found this instance circuit ready to lend a hand while used in conjunction with the Universal Descrambler and a Stabilizer circuit I built instead of making copies of cassette tapes. It not just allowable me the capacity to fine melody the video strength it and helped me redouble the recorded audio which typically becomes poor as making tape copies. Circuit act is straight redirect designed for amplifier circuits. The minute channel for the audio amplifier is made up of the same components excluding the other partly of IC1 is used. Pin 6 & 5 are inputs and 7 is the output.

Video Distribution Amplifier

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LM2876 40W audio power amplifier Diagram Circuit

Using the LM2876 high-performance audio power amplifier circuit can be designed a very simple high efficiency power audio amplifier electronic project capable of delivering 40W of continuous average power to an 8Ω load with 0.1% THD+N from 20Hz–20kHz.
The performance of the LM2876 high-performance audio power amplifier, utilizing its Self Peak Instantaneous Temperature (°Ke) (SPiKe™) protection circuitry, puts it in a class above discrete and hybrid amplifiers by providing an inherently, dynamically protected Safe Operating Area (SOA). SPiKe protection means that these parts are completely safeguarded at the output against overvoltage, undervoltage, overloads, including shorts to the supplies, thermal runaway, and instantaneous temperature peaks.
The LM2876 maintains an excellent signal-to-noise ratio of greater than 95dB (min) with a typical low noise floor of 2.0μV.

As you can see in the circuit diagram , this 40W high-performance audio power amplifier electronic project require few external electronic parts and require few knowledge .
The muting function of the LM2876 allows the user to mute the music going into the amplifier by drawing less than 0.5 mA out of pin 8 of the device.
Upon system power-up the under-voltage protection circuitry allows the power supplies and their corresponding caps to come up close to their full values before turning on the LM2876 such that no DC output spikes occur.
The LM2876 contains overvoltage protection circuitry that limits the output current to approximately 4Apeak while also providing voltage clamping, though not through internal clamping diodes.
The LM2876 has a sophisticated thermal protection scheme to prevent long-term thermal stress to the device. When the temperature on the die reaches 165°C, the LM2876 shuts down. It starts operating again when the die temperature drops to about 155°C
The LM2876 high-performance audio power amplifier circuit operates over a wide input voltage range , from 20 up to 70 volts , but typically a dual 30 volt power supply ( or a single 60 volt in this case ) will be work fine

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Simple Automatic Switch For Audio Power Amplifier

Simple Automatic Switch For Audio Power Amplifier Circuit of an automatic switch for audio power amplifier stage is presented here. The circuit uses stereo preamplifier output to detect the presence of audio to switch the audio power amplifier on only when audio is present. The circuit thus helps curtail power wastage. IC1 is used as an inverting adder. The input signals from left and right channels are combined to form a common signal for IC2, which is used as an open loop comparator. IC3 (NE556) is a dual timer. Its second section, i.e., IC3(b), is configured as monostable multivibrator. Output of IC3(b) is used to switch the power amplifier on or off through a Darlington pair formed by transistors T1 and T2. IC3(a) is used to trigger the monostable multivibrator whenever an input signal is sensed.

Circuit diagram:

Automatic Switch For Audio Power Amplifier Circuit Diagram

Under ‘no signal’ condition, pin 3 of IC2 is negative with respect to its pin 2. Hence the output of IC2 is low and as a result output of IC3(a) is high. Since there is no trigger at pin 8 of IC3(b), the output of IC3(b) will be low and the amplifier will be off. When an input singal is applied to IC1, IC2 converts the inverted sum of the input signals into a rectangular waveform by comparing it with a constant voltage which can be controlled by varying potentiometer VR1. When the output of IC2 is high, output pin 5 of IC3 goes low, thus triggering the monostable multivibrator. As soon as the audio input to IC1 stops, pin 5 of IC3 goes high and pin 1 of IC3 discharges through capacitor C3, thus resetting the monostable multivibrator. 

Hence, as long as input signals are applied, the amplifier remains ‘on.’ When the input signals are removed, i.e., when signal level is zero, the amplifier switches off after the mono flip-flop delay period determined by the values of resistor R8 and capacitor C3. If no input signals are sensed within this time, the amplifier turns off—else it remains on. Power supply for the circuit can be obtained from the power supply of the amplifier. Hence, the circuit can be permanently fitted in the amplifier box itself. The main switch of the amplifier should be always kept on. Resistors R1 and R2 are used to divide single voltage supply into two equal parts.

Capacitors C1 and C2 are used as regulators and also as an AC bypass for input signals. Diode D1 is used so that loading fluctuations in power amplifier do not affect circuit regulation. Transisitor T2 acts as a high voltage switch which may be replaced by any other high voltage switching transistor satisfying amplifier current requirements. Value of resistor R10 should be modified for large current requirement. The LED glows when the amplifier is on. The circuit is very useful and relieves one from putting the amplifier on and off every time one plays a cassette or radio etc. 

Source : EFY

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Single Supply Instrumentation Amplifier

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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Rangkaian Power Supply for tube amplifier

Power supply for EL-34 tube is specially designed for the purposes of power supply at the push-pull amplifier with EL-34 tube as in article 35 Watt Tube Power Amplifier Push Pull before.
Power supply for EL-34 tube amplifier is made with transformers CT and 2 pieces diode as rectifier. Mechanical filters are applied in the power supply uses 3 levels. Power supply for tube power amplifier can deliver output voltages +220 VDC. Circuit details can be seen in the following figure.

The above power supply circuit has a high output voltage so that need to be considered in the manufacture and perakitanya because electricity can tesengat (stun). Power Supply For Tube Power Amplifier With Diode EL-34 was created specifically for the power amplifier tube push pull EL-34.

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10 Watt Power Amplifier

Transistors: Tr1 BCY70 (or BC 182L or BC212L or BC214L) Tr2/3/4 BFY50/51 Tr5 BFX88 Tr6/7 2N3055 Risk of instability if no input connected. When testing, connect R (about 3k3). Needs well smoothed power supply of about 20 to 30 volts. Peak power is well over 10 Watts. The table below shows the approximate voltages to be expected when using a 24v supply and with the variable resistor set to give a current of about 40mA in the output stage.

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High Performance 12V 20W Stereo Amplifier

High-Performance 12V 20W Stereo Amplifier. Amplifiers which run from 12V DC generally don’t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the power and low distortion boxes. With a 14.4V supply, it will deliver 20 watts per channel into 4-ohm loads at clipping while harmonic distortion at lower power levels is typically less than 0.03%. This is an ideal project for anyone wanting a compact stereo amplifier that can run from a 12V battery. It could be just the ticket for buskers who want a small but gutsy amplifier which will run from an SLA battery or it could used anywhere that 12V DC is available – in cars, recreational vehicles, remote houses with 12V DC power or where ever.

20W Stereo Audio Amplifier

Because it runs from DC, it will be an ideal beginner’s or schoolie’s project, with no 240VAC power supply to worry about. You can run it from a 12V battery or a DC plugpack. But while it may be compact and simple to build, there is no need to apologise for “just average” performance. In listening tests from a range of compact discs, we were very impressed with the sound quality. Long-time readers might recall that we presented a similar 12V power amplifier design back in May 2001. It was a similar configuration to this one but it is now completely over-shadowed by the much lower distortion and greatly improved signal-to-noise ratio of this new design. In fact, let’s be honest: the previous unit is not a patch on this new design. It used two TDA1519A ICs which resulted in distortion figures above 1% virtually across the board and a signal-to-noise ratio of only -69dB unweighted.
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20W Stereo Amplifier Circuit

However, by using the TDA­7377 power amplifier IC and making some other improvements, the THD (total harmonic distortion) of the new design is about 50 times better than the older unit (see performance graphs for details). The bottom line is that the THD under typical conditions is around just 0.03% or less. It is also able to deliver more output power due to the improved output transistors in the new power amplifier IC. In addition, its idle power consumption is low – not much more than 1W. As a result, if you don’t push it too hard it will run cool and won’t drain the battery too quickly. And because the IC has self-protection circuitry, it’s just about indestructible. It will self-limit or shut down if it overheats and the outputs are deactivated if they are shorted.

Circuit diagram:

20W Stereo Amplifier Circuit Diagram

With a 12V supply, the largest voltage swing a conventional solid-state power amplifier can generate is ±6V. This results in a meagre 4.5W RMS into 4O and 2.25W RMS into 8O, without considering losses in the output transistors. Even if the DC supply is around 14.4V (the maximum that can normally be expected from a 12V car battery), that only brings the power figures up to 6.48W and 3.24W for 4O and 8O loads respectively – still not really enough. There are three common solutions to this problem. The first is to boost the supply voltage using a switchmode DC converter. This greatly increases the cost and complexity of the amplifier but it is one way of getting a lot of power from a 12V supply. However, we wanted to keep this project simple and that rules out this technique.

Parts layout:

There are variations on the boosting method, such as the class H architecture used in the TDA1562Q IC featured in the Portapal PA Amplifier (SILICON CHIP, February 2003). It is able to achieve 40W/channel but with >0.1% THD. In that case, the amplifier output itself provides the switching for a charge pump. The second method is to lower the speaker impedance. Some car speakers have an impedance as low as 2O, which allows twice as much power to be delivered at the same supply voltage. However, we don’t want to restrict this amplifier to 2O loudspeakers.

Author: Nicholas Vinen - Copyright: Silicon Chip

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