Schematic Reference

Adjust R11 to set quiescent current at 100mA (best measured with an Avo-meter connected in series to Q8 Drain) with no input signal.
    A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 to output ground. Then connect separately the input and output grounds to power supply ground.

The 0.25 Ohm resistor should cause little grief (4 x 1 Ohm 1W resistors in parallel), but some experimentation may be needed here, since the base-emitter voltage of the BC549 determines the current. This circuit works by using the BC549 to steal any excess base current from the compound pair. As soon as the voltage across the 0.25 Ohm resistor exceeds 0.65V, the transistor turns on and achieves balance virtually instantly.

The 1k trimpot in the collector of the first LTP transistor allows the DC offset to be adjusted. The nominal value is around 400 ohms, but making it variable allows you to set the output DC offset to within a few mV of zero.

The values of R5 and C8 are worked out from the equations in the datasheet, but I used 1.8k ohm for R5 and 220pF for C8 and they work fine. Diodes should be 1N4001 or similar (make sure you solder them in the right way round).

A good heatsink is important and this should be a large size with good thermal conductivity. When you operate the TDA2030 from the (recommended) split rail power supply, you must insulate the device from the heatsink using a mica washer or similar. With single rail supply, this is not needed.

Why Class A ? Because , when biased to class A, the transistors are always turned on, always ready to respond instantaneously to an input signal. Class B and Class AB output stages require a microsecond or more to turn on. The Class A operation permits cleaner operation under the high-current slewing conditions that occur when transient audio signal are fed difficult loads. His amplifier is basically simple, as can be seen from the block diagram.

In use, R9 should be carefully adjusted to provide minimal audible signal cross-over distortion consistent with minimal measured quiescent current consumption; a good compromise is to set the quiescent current at about 10-15 mA.To measure this current, wire a DC current meter temporarily in series with the collector of Q3.

List Component

• P1_____________10K Log.Potentiometer
• R1,R2__________33K 1/4W Resistors
• R3_____________33R 1/4W Resistor
• R4_____________15K 1/4W Resistor
• R5,R6___________1K 1/4W Resistors
• R7____________680R 1/4W Resistor
• R8____________120R 1/2W Resistor
• R9____________100R 1/2W Trimmer Cermet
• C1,C2__________10µF 63V Electrolytic Capacitors
• C3____________100µF 25V Electrolytic Capacitor
• C4,C7_________470µF 25V Electrolytic Capacitors
• C5_____________47pF 63V Ceramic Capacitor
• C6____________220nF 63V Polyester Capacitor
• C8___________1000µF 25V Electrolytic Capacitor
• D1___________1N4148 75V 150mA Diode
• Q1____________BC560C 45V 100mA PNP Low noise High gain Transistor
• Q2____________BC337 45V 800mA NPN Transistor
• Q3____________TIP31A 60V 4A NPN Transistor
• Q4 ___________TIP32A 60V 4A PNP Transistor
• SW1___________SPST switch

Pin Name Description
1 Vcc Supply Voltage
2 RR Ripple Reject
3 MC Muting control
4 OP AF Signal Input
5 FB FB Filter
6 GA Gain adjust
7 GND Ground
8 GND Ground
9 OP AF Output
10 BS BootStrap

Adjust the volume control on the minimum and R3 position with a minimum value of resistance as well. try to switch the circuit set in R3 to read the flow of about 20 to 25mA. Wait for 15 minutes, connect the ground of A1, P1, C2, C3dan C4. Connect the output also C9 ground

List Component

• P1 : 22K Log Potemsiometer (Dual gang for stereo)
• C3, 4 : 470uF/25V
• P2 : 100K Log Potemsiometer (Dual gang for stereo)
• C6 : 47pF 63V ceramic ar polyester capasitor
• R2, 4, 8 : 820R 1/4W
• C7 : 10nF 63V polyester capasitor
• R1 : 4K7 1/4W
• C9 : 100nF 63V polyester capasitor
• R3 : 500R 1/2W
• D1 : 1N4148 75V 150mA Diode
• R5 : 82K 1/4W
• IC 1 : NE5532 Low noise Dual Op-amp
• R6, 7 : 47K 1/4W
• Q1 : BC547B 45V 100mA NPN Transitor
• R9 : 10R 1/2W
• Q2 : BC557B 45V 100mA PNP Transitor
• R10 : 0,22 4W(wirewound)
• Q3 : TIP42A 60V 6A PNP Transistor
• C1, 8 : 470nF 63V polyester capasitor
• Q4 : TIP41A 60V 6A NPN Transistor
• C2, 5 : 100uF/25V J1 : RCA audio input socket

I have Used it with Sennheiser 465s and achieved ear-splitting volume. The amplifier is ideal as a booster for power-conserving stereo sources Such as portable CD players and for interfacing with passive EQ networks Such as tone controls or a headphone acoustic simulator.

The extremely reduced components count allows very compact sets. The on-board clipping detector simplifies gain compression operations. The fault diagnostics makes it possible to detect mistakes during Car- Radio assembly and wiring in the car.

Absolute maximum ratings of IC TDA7295 IC

•     Operating supply voltage = 18 V
•     DC supply voltage = 28 V
•     Peak supply voltage (t = 50 ms) = 50 V
•     Output peak current Repetitive (duty cycle 10 % at f = 10 Hz) = 3 A
•     Output peak current Non repetitive (t = 100 µs) = 4A
•     Power dissipation, (Tcase = 70 °C) = 80 W
•     Junction temperature = 150 °C
•     Storage temperature = -40 to 150 °C

IC TDA7052 is a mono output amplifier in 8-comng Head DI package (DIP). The device is designed primarily for battery-operated portable audio circuits. Features include TDA 7052, no external components needed, no switch-on or switch-off button sounds great overall stability and very low power consumption (quiescent current of 4 mA), low THD, it is not necessary any cooler and short-circuit proof.

Profit TDA 7052 is set internally at 40 dB. . Compensate for the reduction of output power due to low voltage TDA7052 uses Bridge-Tied-Load principle
(BTL), which can provide power about 1 to 2 W RMS (THD = 10%), 8 ohm load to the power supply 6 V.

Chances are you'll want this amplifier portable. Batteries do the trick fine, but you won't get much power out of a couple of 1.5V cells. Unfortunately the size of a decent amount of battery power will mean that the overall size of this amp will be much bigger and for that there are more benefits to be had using a device like the TDA7052 or TDA2822 for stereo.

Quick ref data of TDA1015T Chip

•     Supply voltage range: 3,6 to 12 V
•     Peak output current: 1 A
•     Output power: 0,5 W
•     Voltage gain power amplifier: 29 dB
•     Voltage gain preamplifier: 23 dB
•     Total quiescent current: 22 mA
•     Operating ambient temperature range: -25 to +150 °C
•     Storage temperature range: -55 to + 150 °C