BJT Class AB Power Amplifier

INTRODUCTION:

I found an old radio and cassette player circuit from my collection of old circuits. This circuit consists of three different ICs i.e. TA8127N which is an stereo AM/FM superheterodyne receiver chip. second is TA8119 Which is an Stereo cassette playback pre amplifier and equalizer. The last IC is KA2402 which is used to control the speed of motor of the cassette player. After observing the circuit, I found that there is no power amplifier section on the circuit, So I decided to make a low power audio power amplifier so that we can test the circuit. For this separated the radio section of the PCB by cutting it out by saw. Now I soldered four wires to to the radio PDB.

Red------------> for 6V DC supply

Black----------->for GND

Yellow--------->for audio output

White----------->for FM antenna

List of electronic Components:

BC548 Transistor (NPN)

https://quartzcomponents.com/products/bc548-npn-amplifier-transistor?_pos=1&_sid=60f551ae2&_ss=r

BC558 Transistor (PNP)

https://quartzcomponents.com/products/bc558-pnp-transistor?_pos=1&_sid=434c3bdc1&_ss=r

Resistor (1K, 120K)

https://quartzcomponents.com/products/1k-ohm-1-4-watt-resistor-with-1-tolerance-pack-of-10?_pos=2&_sid=e29b50736&_ss=r

https://quartzcomponents.com/products/120k-ohm-1-4-watt-resistor-with-5-tolerance-pack-of-10?_pos=1&_sid=4c48336d8&_ss=r

Capacitors (0.1UF, 220UF/16V, 100UFF/25V)

https://quartzcomponents.com/products/10000-pf-0-1uf-ceramic-capacitor?_pos=1&_sid=04c8310ef&_ss=r

https://quartzcomponents.com/products/16v-220uf-electrolytic-capacitor?_pos=2&_sid=d46c8684d&_ss=r

https://quartzcomponents.com/products/100uf-25v-radial-electrolytic-capacitor?_pos=1&_sid=53903d6de&_ss=r

Potentiometer 10K

https://quartzcomponents.com/products/wh148-single-potentiometer-b10k-3pin-15mm-2?_pos=2&_sid=0808c3a1f&_ss=r

Diode (1N4148)

https://quartzcomponents.com/search?type=product&q=1N4148

Bread Board

https://quartzcomponents.com/products/colored-breadboard-mb-102-830-point?_pos=2&_sid=2db239d4c&_ss=r

Jumper Wire (male to male)

https://quartzcomponents.com/products/65pcs-breadboard-jumper-cable?_pos=7&_sid=6923e0f92&_ss=r

Lab bench power supply (0-15V) or 6V Battery.

Loudspeaker

https://quartzcomponents.com/products/0-5w-speaker-8-ohm-large?_pos=4&_sid=f3d1e3c40&_ss=r

Cut out the radio part of the circuit carefully using a saw. then solder four wires to the circuit as shown in the fig. for Vcc, GND, audio output and antenna.

Make a prototype circuit of the power amplifier on the bread board. You can take the help of the schematic diagram to make the circuit. After making all the wire connections recheck your connections before power the circuit. Provide the 6V volt DC power to the circuit using the lab bench power supply. Connect the radio circuit to the amplifier circuit. Use the same power supply to power radio circuit and amplifier.

I have also used a 10K potentiometer to adjust the volume level. 1N4148 diode is not available in my lab so I am using 1N4007 instead of 1N4148,