Analog circuit

Analog circuit is a electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two different levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that represents the signal. The word analogue is derived from the Greek word ανάλογος (analogos) meaning "proportional".

Electronic circuit

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another. Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as silicon or gallium arsenide. Article: ww.wikipedia.org

Circuit

Type of electrical engineering circuit

• Electronic circuit, active electronic components connected in a circuit
• Analog circuit 
• Mixed-signal integrated circuit
• Digital circuit
• Synchronous circuit
• Printed circuit board (PCB)
• Series and parallel circuits
• Telecommunication circuit
• Circuit diagram
• Balanced circuit
• Integrated circuit
• Asynchronous circuit 
• LC circuit

...

10W Class D power amplifier

The TDA7480 is a class D audio amplifier assembled in Power DIP (PDIP20) package, specially designed for high efficiency applications, capable of 10W output power at a load of 8w/4w and a total harmonic distorsion of 10%. Requires a split-supply (max. ±20V).

The main selling point of this amplifier is the very low dissipated power compared to normal class AB amplifiers. Only a small "on board" copper area heatsink is required for normal operation. The IC has built-in stand-by and mute feature, overvoltage protection, short circuit protection and thermal overload protection.


The output of the amplifier is a high frequency square wave (~100Khz), rail to rail, with variable duty cycle. To obtain the audio signal, the output must be low pass filtered. The preamplifier provides the voltage gain of the overall amplifier. The second stage is the class D power stage, with a gain 1.5. The class D amplifier stage is done with a multivibrator. With no signal it generates a 50% duty cycle square wave, with signal applied, it changes the duty cycle. The switching frequency is set by the voltage on pin 9.

The most important filter capacitor is C5 between the pins 16 and 17. The value of the parasitic inductance between this capacitance and the IC pins is related to the amplitude of the spikes on the power supply pins at every commutations of the output. For any commutation, there is an abrupt variation of the current in the parasitic inductances in series to the supply. This abrupt variation increases as the output current increases and can be typically of a few amperes on 10ns. With this slew rate of the current, an inductance of a few nH (i.e. the lead inductance of the pin) generates voltage spikes in order of volts. These spikes can cause distortion / offset increase due to the non linear coupling on the internal elementary devices in the signal circuit, overvoltage on the IC, strong noise on the logic signals inside the chip causing incertain logic levels, dangerous for the IC. To avoid these spikes, it is mandatory to put a quality bypass capacitor at a distance lower than 5mm from the pins.

The capacitor C8 on pin 9 must be a low inductance type and should be placed close to the IC. The voltage on this pin sets the switching frequency. The purpose of C8 is to filter the high frequency noise from entering the IC as it could generate distortion/offset.

C4 on pin 8 sets the bandwidth of the class D amplifier. It is important that the reference ground of this capacitor is as near as possible to the IC signal ground.

C3 on pin 11 filters the high frequency noise that can enter in the input and that can cause intermodulation aliasing noise at the output. No signal at frequency greater than half of the switching frequency can enter in the IC without generating aliasing noise.

The electrolitic capacitors must have a good ESR, ESL at switching frequency (around 100Khz) and a sufficient maximum operating voltage.

The low pass filter placed after the switching stage is dimensioned to eliminate the high frequency PWM waves and to feed the audio signal to the loudspeaker. The losses in the filter capacitor C14 due to the ESR will be neglegible if multilayer film capacitors are used.Multilayer Mylar, Polypropilen or Policarbonate film capacitors are recomended, avoid using ceramic capacitors.

The losses in the inductor L1 at low frequencies are mainly due to the coil winding series resistance. At higher frequencies, where the Skin Effect becomes of importance, a multiwire winding could be effective to obtain the maximum in terms of efficiency. However, for most of the applications the use of a single wire winding with adequate cross section is enough. The inductor used for the filter must sustain a DC current greater than the specified current limitation value without saturation and the coil material must show very low hysteresis losses.

Audio Amplifier LM386

Audio Amplifiers with LM386




The LM386 is a versatile, small power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but with the addition of an external resistor and capacitor between pins 1-8 the gain can be set to any value from 20 to 200.

The inputs are ground referenced and the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 Volt supply, making the LM386 ideal for battery operation.



To make the LM 386 a more versatile amplifier, 2 pins (pin 1 and 8) are provided for gain control. With pins 1 and 8 open the internal 1.35k resistor sets the gain at 20 (26 dB). If a capacitor is placed between pin 1-8, bypassing the built-in 1.35k resistor, the gain will go up to 200.

If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor or FET transistor from pin 1 to the ground.

Simple audio amplifier schematics with LM386

• Operating Supply Voltage (VS) = 4v - 12v 
• The output power (POUT) for LM386N-1, LM386M-1 at VS = 6V, RL = 8ohms, 
• THD = 10% is 250-325 mW for LM386N-3 at VS = 9V, RL = 8ohms, 
• THD = 10% is 500-700 mW for LM386N-4 at VS = 16V, RL = 32ohms, 
• THD = 10% is 700-1000 mW. 

Fig 1: LM386 Audio Amplifier with Gain = 20 and minimum part count


Fig 1: LM386 Audio Amplifier with Gain = 200


Fig 1: Audio Amplifier with bass boost

200W Subwoofer Amplifier Circuit

Circuit Description

Here is a circuit that uses a mosfet amplifier amplicable for subwoofer as the main booster, or the basis of this boosterAmplifier. Circuit which uses MOSFET Power Amplifier is powered by the output more than 200W Speaker 8 Ohm impedance. We also include a suitable power supply circuit with the use of MOSFETamplifier with 200W of power, not only of his course Schematic diagram for the layout design is also already there.

Amplifier Circuit Diagram

Amplifier Circuit Diagram

200W Mosfet Amplifier LAyout PCB

200W Mosfet Amplifier LAyout PCB

Regulator Circuit Diagram MOSFET AMPLIFIER

Regulator Circuit Diagram MOSFET AMPLIFIER

Regulator PCB MOSFET amplifier

Regulator PCB MOSFET amplifier

Amplifier Circuit Diagram

Description:

I have been looking for a good stereo amplifier circuit diagram for a long time. I am not a HiFi geek, I just wanted to build a simple stereo amplifier that could drive some speakers for my desktop computer.

All the schematic diagrams that I could find seemed to involve lots of hard-to-find components or you had to use it together with a pre-amplifier or some other amplifier stage. It was always something that made me hesitate. But recently I found this awesome little chip called TEA2025! You only need a few capacitors to make a decent stereo amplifier out of it. It is so simple to build that I put it together on a strip board in just a few hours. The amplifier circuit diagram shows a 2.5W * 2 stereo amplifier. You can also make a 5W mono amplifier out of it. On the input side, you should use a dual potentiometer. A dual potmeter allows you to connect both left and right channel on one potentiometer. This amplifier is great to use together with some speakers to get sound on your desktop computer. I am thinking of putting one in my kitchen and in my bathroom also. Then maybe hook them up to my home network and stream music from a server =) There are many possibilities when you can make such a cheap amplifier.

Amplifier circuit diagram:

Amplifier circuit diagram