High Voltage 3 Watt Audio Power Amplifier

The LM4954 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 2.4 Watts of continuous average power to an 8 BTL load with less than 1% THD+N from a 7V_DC power supply. Boomer audio power amplifiers are designed specifically to provide high quality output power with a minimal number of external components. The LM4954 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for lower-power portable applications where minimal space and power consumption are primary requirements.

High Voltage 3 Watt Audio Power Amplifier Circuit Diagram

The LM4954 features a low-power consumption global shutdown mode which is achieved by driving the shutdown pin with logic low. Additionally, the LM4954 features an internal thermal shutdown protection mechanism.

The LM4954 contains advanced pop & click circuitry which eliminates noises that would otherwise occur during turn-on and turn-off transitions.

The LM4954 is unity-gain stable and can be configured by external gain-setting resistors.

Key Specification:

Wide Power Supply Voltage Range	2.7 <= VDD <= 9V
Output Power: VDD = 7V, 1% THD+N	2.4W (typ)
Quiescent power supply current	3mA (typ)
PSRR: VDD = 5V and 3V at 217Hz	80dB (typ)
Shutdown power supply current	0.01µA (typ)

Features:

No output coupling capacitors, snubber networks or bootstrap capacitors required

Unity gain stable

Externally configurable gain

Ultra low current active low shutdown mode

BTL output can drive capacitive loads up to 100pF

"Click and pop" suppression circuitry

2.7V - 9.0V operation

Available in space-saving microSMD package

Applications

Mobile Phones

PDAs

Source: http://www.ecircuitslab.com/2011/06/high-voltage-3-watt-audio-power.html

{ Read More }

Simple 3 Way Active Crossover Circuit Diagram

This is the Simple 3-Way Active Crossover Circuit Diagram with linear phase response. The problems that exist at common crossover circuit is known. The low pass filter causes a delay in the signal. Unlike the high-pass filter causes a head in the signal passing through it. Thus the frequency separation created some problems such as:

1. Signals of the two filters are mutually exclusive
2. The phase shift between the filter affects the radiation
3. The radiation pattern depends on the frequency

The crossover circuit tries to solve many of the problems mentioned above and based on a study of S. Lipshitz and J.  Vanderkooy, published in the JAES (Journal Audio Engineering Society). A lattice separation uses a linear phase low-pass section with the help of a time delay circuit and a circuit removal gives the output signal with high-pass filter characteristics. The time delay is not constant over the entire frequency range, but changing very slowly and mainly there are phase differences between signals of the two charges, not even close to the crossover.

Simple 3-Way Active Crossover Circuit Diagram

The circuit consists separation as shown in block diagram [Fig.2] two low pass filters of fourth grade, -24db/oct for a line of low-frequency signals and one for the high frequency separation. In the same frequencies operate both units delay time T1 (for low frequency F1) and T2 (for high frequency F2) and give the same phase characteristics of the low pass section.

The delay circuit T1 simulates the time delay introduced by low-frequency filter LPF1, while T2 simulates the time delay introduced by low-frequency filter LPF2 that exists in the line of midrange. Then the signal from the low pass filter removed [IC7A-B] of the signal has been delayed, a clear signal that the characteristics are the same as a signal that has passed through a high pass filter. At the exit of each line is a trimmer with which we can adjust the level between the levels of loudspeakers. The power circuit is a well-stabilized voltage + /-15V. The use of meshed split fourth order Linkwitz forcing crossovers be located at-6db [Fig.3].

The above picture shows the main circuits and the necessary formulas for calculating the low pass filters as well as trusses time delay. There is also an example calculation for crossovers and 200IZ 3KIZ that will help calculate and adjust to your needs. The circuit derived from a relevant article of the magazine Elektor. 

Components List:
R1,16 = 100Kohms
R2,3,4,5 = 56Kohms
R6,27 = 37.5Kohms[33K+4.7K]
R8,9,12,13,14 = 10Kohms
R10,28 = 75Kohms (150K//150K)
R11,29 = NC
R15 = 56.3Kohms
R17 = 12Kohms
R18,19,20,21,22 = 10Kohms
R23,24,25,26 = 37.5Kohms [33K+4.7K]
R30,31,32,33,34,35,36 = 10Kohms
R37,38,39,40,41,41 = 10Kohms
R42,43,44 = 47Kohms
R45,46 = 47 ohms
TR1,2,3,4 = 47Kohms trimmer or pot.
C1,34,35 = 2.2uF 100V MKT
C2,3,7,8,14,15,18 = 47nF 100V MKT
C4,5,6,9,10,11,16,17 = 10nF 100V MKT
C12,13,20,21,22 = 1nF 100V MKT
C19,23,24,30,31,32,33 = 47nF 100V MKT
C25,26,27,28,29 = 1nF 100V MKT
C36,37 = 1uF 100V MKT
C38,39 = 47uF 25V
IC1 = TL071
IC2,3,4,5,6,7 = TL072,NE5532
All the resistors is 1/4W 1% metal film

Sourced by Elektor

{ Read More }

IR Remote Control Extender Mark 3

This Mark3 version of the Infra Red extender is a special version designed to control appliances that use high frequency modulated IR remote controls.

Notes:
IR appliances use pulses (control signals) sent over a modulated IR carrier wave. The carrier wave may be modulated at various frequencies, 36-38KHz being the most popular.Some Satellite receivers use even higher frequencies than this. The IR1 remote module receives an infra red signal and separates control pulses from the modulation. To re-transmit, a 555 timer is configured as an astable oscillator. The 555 timer is controlled by the signal on the reset pin, high generating a carrier and low no carrier. Each control pulse turns on the oscillator for the duration of a logic high signal and off for a logic 0 signal, thereby creating a newly modulated IR signal. The IR module, part number IR1 is available from Harrison Electronics in the UK, IR1 may not be listed in their catalogue but if you ask for an IR1, they will send you the correct part. The IR1 arrives in a small aluminium case, the connections viewed from underneath are shown below:

Infra Red Module, IR1 Pinout

Harrison Electronics have limited supplies of the IR1 but as a replcement a standard IR module like the TSOP1838 may be used. The pinout is shown below:

The carrier frequency is determined by R1 and C3, values shown work at 39.7 kHz, but these may be altered to provide different carrier frequencies. The final CMOS 4049 invertor ensures that under "no signal" conditions both LEDs are also off.

Parts List:
C1 100u 10V
C2 100n polyester
C3 120p silver mica
C4 100n polyester
R1 150k
R2 2k2k
R3 1k
R4 47R 1W
Q1 BC109C
IC1 LM7805
IC2 555
IC3 IR1 module from Harrison Electronics or TSOP1838
IC4 4049 CMOS Invertor LED1 Red LED (or any visible colour)
LED2 TIL38 or part YH70M from Maplin Electronics


PCB Layout (courtesy of Claudio from Italy):
First the component side of the board is shown below.

And now thw pcb itself.

The Mark 3 circuit is an improvement over the Mark 1 and 2 circuits, however the drive from Q1 inverts the polarity of the output pulse. In some cases this can cause problems so the output stage is rewired as an emitter follower. This is the basis for the Mark 4 circuit. If you still have problems then I would recommend trying the Mark 4 circuit.

{ Read More }

BTL Stereo Amplifier TDA7052 3

This is BTL stereo power amplifier with basic amplifier on IC TDA7052 / TDA7053

{ Read More }