Showing posts with label class. Show all posts
Showing posts with label class. Show all posts
Monday, October 27, 2014
NCS8353 20 W stereo Class D audio amplifier Diagram Circuit
A very simple stereo Class D audio amplifier electronic circuit project can be designed using the NCS8353 audio IC capable of delivering a continuous power of up to 20 W/ch into an 8 ohms .
NCS8353 stereo Class D audio amplifier circuit is designed by ON Semiconductor and it can be powered from the existing 24 V rail in Flat Panel Television (FPTV) systems. The high efficiency of the NCS8353, 86%, reduces the requirement of an external heat sink when driving high power.
The digital power limit feature can program the output power limit at 10 W, 12 W, 15 W, or 20 W/ch, allowing the NCS8353 to be a single system solution in FPTV audio applications.
The digital power limiter quickly reduces the internal gain of the amplifier when high amplitude signals would cause excessive clipping on the output.
The gain of the NCS8353 is programmed via two gain pins, G0 and G1, allowing four selectable ranges: 20 dB, 26 dB, 32 dB, and 36 dB.
Auto recovery short circuit and over temperature protection circuitry are incorporated to ensure device functionality after short circuit and high temperature events occur .
The circuit can be powered from a wide input voltage range from 8 volt DC up to 26 volt DC .
Thursday, September 18, 2014
Class A Headphone Amplifier
This circuit is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.
Circuit diagram :
Class-A Headphone Amplifier Circuit diagram
The above mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble lift and bass cut.
Note:
- Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to zero resistance and Trimmer R3 to about the middle of its travel.
- Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.
- Connect a Multimeter, set to measure about 10Vdc fsd, across the positive end of C5 and the negative ground.
- Switch on the supply and rotate R3 in order to read about 7.7-7.8V on the Multimeter display.
- Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 200mA fsd, in series to the positive supply of the amplifier.
- Switch on the supply and rotate R6 slowly until a reading of about 100mA is displayed.
- Check again the voltage at the positive end of C5 and readjust R3 if necessary.
- Wait about 15 minutes, watch if the current is varying and readjust if necessary.
Parts List :
P1 : 22K Dual gang Log Potentiometer
R1 : 15K
R2 : 220K
R3 : 100K
R4 : 33K
R5 : 68K
R6 : 50K
R7 : 10K
R8,R9 : 47K
R10,R11 : 2R2
R12 : 4K7
R13 : 4R7
R14 : 1K2
R15,R18 : 330K
R16 : 680K
R17,R19 : 220K
R20,R21 : 22K
C1,C2,C3,C4 : 10µF/25V
C5,C7 : 220µF/25V
C6,C11 : 100nF
C8 : 2200µF/25V
C9,C12 : 1nF
C10 : 470pF
C13 : 15nF
D1 : LED
D2,D3 : 1N4002
Q1,Q2 : BC550C
Q3 : BC560C
Q4 : BD136
Q5 : BD135
IC1 : 7815
T1 : 15CT/5VA Mains transformer
SW1 : 4 poles 3 ways rotary Switch
SW2 : SPST slide or toggle Switch
www.ecircuitslab.com
Tuesday, August 26, 2014
Hi Fi 25W Power Amplifier Class A
Hi-Fi 25W Power Amplifier (Class-A) Schematics Circuit
| Click to view larger |
Sunday, August 24, 2014
Class A power amplifier
Examples of class A amplifier is the basic transistor circuit common emitter (CE). Amplifier type class A is made by setting dititik bias current (usually Q) on the load line. The position of point Q such a way that is right in the middle line of the load curve VCEIC from the amplifier circuit.
The is an example circuit with common emitter NPN transistor Q1.
Line load on this amplifier determined by the resistor Rc and Re from the formula VCC = VCE + ICRC + IeRe. If Ie = Ic, it can be simplified into VCC = VCE + Ic (Rc + Re). Next line load circuit can be described by a formula them. While resistors Ra and Rb were installed to determine the bias currents. Magnitude resistors Ra and Rb in related series determining how much current Ib the cut point Q. Large Ib flows usually listed on the data sheet used transistors.
Great strengthening AC signals can be calculated with an AC signal circuit analysis theory. In an AC circuit analysis of all components of the capacitor C connected brief and the imaginary connecting the VCC to ground. With In this way a series of images 1-18 can be assembled into such picture 1-20. Resistors Ra and Rc is connected to GND and all short-circuited capacitor.
Typical class A amplifier, all output signals to work on active region. Amplifier type class A is called as a reinforcement that has fidelitas a high level. Provided the signal is still working in the active region, form the output signal will exactly match the input signal. But class A amplifier has low efficiency of approximately only 25% - 50%. Its none other since the point Q is at point A, so that although there is no input signal (or when the input signal = 0 Vac) transistors to keep working in the active region with a constant bias current. Transistor is always active (ON) so that most of the sources of supply wasted power into heat. Since this is class A transistor amplifier should be augmented with extra cooling like heatsinks are more large.
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