Rangkaian Audio Amplifier LM4780

Exploring power amplifier integrated circuit LM4780 from National Semiconductor.

What's so special? Well, first of all - a very low harmonic distortion. Usually, manufacturers indicate the maximum power of its regular ingenious handicrafts with the harmonic content of 10%. At the same chip, CT at the maximum specified power is only 0,5%! Thus, it is the most honest of all mikruha I encountered.

In the chip implements two identical amplifier channels and features are given for the stereo mode of the amplifier. Circuit can also operate in mono - in bridge inclusion. In this case, the output power at CT = 0.5% of 120 watts. Other features remain virtually unchanged.

Skema rangakain amplifier 60W stereo LM4780

Skema rangakain amplifier 120W Bridged LM4780

LM4780 IC Fiture

• Features SPiKe Protection
• Low external component count
• Quiet fade-in/out mute mode
• Wide supply range: 20V - 84V
• Signal-to-Noise Ratio ≥ 97dB (ref. to PO = 1W)

LM4780 IC pin

50 Watt Rms Audio Amplifier

50 Watt Rms Audio Amplifier

Power amplifier is very important role, because the greater the power used amplifeir the better the sound can also be produced. by using the power amplifier that has a great power will strengthen the energy pounding bass tone or low tone, while the high tone or treble tone quality is maintained.

In skame series of images below presented the series of power amplifiers with 50 watts rms amplifier using NPN and PNP transistors 2n is 2n 7391 and 3055. if the scheme is not clearly visible Kilik so please double picture more clearly visible

Skema Rangkaian 50 Watt Rms Audio Power Amplifier

Note:

• Transistor Q3 and Q4 must be in pairs with the heatsink.
• Use a well regulated and filtered power supply.
• Connect a 10K POT in series with the input as volume control if you need.Not shown in circuit diagram.

List Component:

R1 1 200 Ohm 1/4 W Resistor
R2 1 200K 1/4 W Resistor
R3 1 30K 1/4 W Resistor
R5 1 1K 1/4 W Resistor
R6 1 5K 1/4 W Resistor
R7,R10 2 1 Meg (5%) 1/2 W Resistor
R8,R9 2 0.4 Ohm 5 W Resistor
R11 1 10K Pot R12,R13 2 51K 1/4 W Resistor
R14 1 47K 1/4 W Resistor
C1 1 100uF 35V Electrolytic Capacitor
C2 1 0.011uF Capacitor
C3 1 3750pF Capacitor
C4,C6 2 1000pF Capacitor
C5,C7,C8 3 0.001uF Capacitor
C9 1 50pF Capacitor
C10 1 0.3uF Capacitor
C11,C12 2 10,000uF 50V Electrolytic Capacitor
U1,U2 2 741 Op Amp
U3 1 ICL8063 Audio Amp Transister Driver thingy
Q1 1 2N3055 NPN Power Transistor
Q2 1 2N3791 PNP Power Transistor
BR1 1 250 V 6 Amp Bridge Rectifier
T1 1 50V Center Tapped 5 Amp Transformer
S1 1 SPST 3 Amp Switch S2 1 DPDT Switch
F1 1 2 Amp Fuse
SPKR1 1 8 Ohm 50W Speaker
.

Audio Amplifier Berbasis Op-Amp

Rangkaian Audio Power Amplifier Berbasis Op-Amp

The amplifier is based on the commonly used class-AB complementary power amplifier with compound pair output transistors. The system uses a TL074 quad opamp to drive the output transistors. As can be seen from figure 1, A2 is used to set the voltage gain of the amplifier. Assuming the voltage gain of a common collector stage to be unity, the overall voltage gain of the amplifier is equal to (R4 / R3) + 1, i.e. the gain of a non-inverting OP-AMP (16 or 24dB, in this case). Since the output transistors are within the feedback loop of A2, A2 also acts to linearise the input characteristic of the complementary pair Q1/Q2 & Q3/Q4. This allows for greater mismatch between the NPN-PNP transistors.

Skema Rangkain Audio Amplifier Berbasis Op-Amp

The biasing to Q1 & Q3 is provided by R6, R7 & diodes D1 & D2. This arrangement biases the transistors just above cut-off and reduces crossover distortion. R6 must be adjusted to the highest value which eliminates crossover distortion. Ideally D1 & D2 should be mounted so they are in contact with the driver transistors - not the main heatsink.

To adjust R6 without an oscilloscope, start with R6 set to maximum, set the volume control R2 to get the minimum audible output with a suitable input source (such as a CD player which gives 0.65Vrms at line out), and listen for any "crackle" in the sound, especially that which seems to be riding on low frequency sounds. If a "crackle" is heard then reduce the value of R6 in very small steps, until the crackle (crossover distortion) becomes inaudible (it can't be eliminated, I feel).

As the output of opamp A2 is being pulled up by the biasing circuit, capacitor C5 must be connected between the output of A2 and ground to prevent the circuit from breaking into oscillations. The value of C5 is not critical, any value between 22nF to 100nF will do. The opamp A1 is a simple buffer which isolates the input circuit from the power stage. C1 & R1 are used to set the lower 3db frequency to around 15Hz, and to obtain an input impedance of about 100K. The upper 3db frequency is determined by R4 & C7, which in this case is approximately 30KHz. The schematic shows only one channel of the stereo amplifier. The amplifier can be used to drive speakers with impedance ranging from 3 Ohms to 8 Ohms, higher impedance speakers could be used but the power output will be substantially less.

The voltage gain of the amplifier can be increased by increasing R4 or decreasing R3, as long as the output swing is kept less than or equal to 3 Volts below the supply rails. This is due to the fact that the maximum output voltage of an opamp is always 2-3 Volts less than the supply rails, before it clips.

source sound.westhost.com

Jengkol 2n3055-MJE2955 Amplifier 80 Watt

Jengkol 2n3055-MJE2955 Power Amplifier 80 Watt

This amplifier does not claim to be "state of the art", and in fact the base design is now over 20 years old. It is a simple amp to build, uses commonly available parts and is stable and reliable. The design featured is a slight modification of an amp I originally designed many years ago, of which hundreds were built. Most were operated as small PA or instrument amps, but many also found their way into home hi-fi systems. The amp is capable of driving 4 Ohms, but it is starting to push the limits of the transistors, however, even when used at 4 Ohms, very few failures were encountered.

This amplifier circuit no output short circuit protection, so if speaker leads are shorted while the amp is working (with signal), there is a very real risk of the transistors being destroyed. Since this amp was built commercially, the savings were worth the risk - most of these amps were installed in the speaker box, so shorting was not likely (unless the loudspeaker voice coil shorted as happened a few times). Because of the cost of the devices used (minimal), it is a cheap amp to fix even if you do manage to blow it up.

Skema Rangkaian 2n3055 Amplifier 80 Watt

If you do not have a dual output bench power supply - Before power is first applied, temporarily install 22 Ohm 5 W wirewound "safety" resistors in place of the fuses. Do not connect the load at this time! When power is applied, check that the DC voltage at the output is less than 1V, and measure each supply rail. They will be different, because of the zener diode feed resistance, but both should be no less than about 20V. If widely different from the above, check all transistors for heating - if any device is hot, turn off the power immediately, then correct the mistake.

Once all appears to be well, connect a speaker load and signal source (still with the safety resistors installed), and check that suitable noises (such as music or tone) issue forth - keep the volume low, or the amp will distort badly with the resistors still there if you try to get too much power out of it.

If the amp has passed these tests, remove the safety resistors and re-install the fuses. Disconnect the speaker load, and turn the amp back on. Verify that the DC voltage at the speaker terminal does not exceed 100mV, and perform another "heat test" on all transistors and resistors. Turn off the power, and re-connect speaker and music source.

Thanks to sound.westhost.com

75 watt 2N3055 Power Amplifier

Amplifier power is a circuit of electronics that is used to strengthen the power (or energy in general). In the field of audio, amplifier will amplify the sound signal (which has been expressed in the form of electric current) on the input it into electric current is stronger at the output. The amount of strengthening is often known by the term gain. Value of the gain is expressed as a function of frequency is called the transfer function.

So the gain is the result of the power output (Pout) and power at the input to its function in the form of frequency. The size of the gain, (G) is usually the Decibel (dB).

2N3055 Power Amplifier

Skema 2N3055 Power Amplifier . The optimal supply voltage is around 30V, but this amp work from 24 to 32V. The maximal input voltage is around 0.8 - 1V. As you can see, in this design the components have a big tolerance, so you can build it almost of the components, which you find at home. The and transistors can be any NPN type power transistor, but do not use Darlington types. The output power is around 150 Watt.

Skema Rangkaian 2N3055 Power Amplifier

capacitor C1 regulates the low frequencies (bass), as the capacitance grows, the low frequncies are getting louder.

capacitor C2 regulates the higher frequencies (treble), as the capacitance grows, the higher frequencies are getting quiter.

this is a class B amplifier, this means, that a current must flow through the end transistors, even if there is no signal on the input. This current can be regulated with the 500Ω trimmer resistor. As this current incrases, the sound of the amplifier gets better, but the end transistors are more heating. But if this current decrases, the transistors are not heating so much, but the sound gets worse.