Power amplifier electronic circuits-tube audio rf amplifiers

About The Circuit

Given below is the desription of an audio circuit using a single transistor. This is the simplest of all the audio mixer circuits and very easy to make as it has only one transistor. The diodes D1 and D2 are used to bias the base-emitter junction of the transistor. The signals to be mixed are coupled directly to the base of the transistor Q1. 33K Ohm resistors are used to limit the current to the input lines. A 10k POT can be added in series to the lines so as to adjust the gain of the induvidual channels. The input power needed for the circuit is 15V dc. A total of 1mA is calculated to be the collector current of the transistor Q1. It would be better if the whole circuit is properly assembled on a Vero board.

Circuit Schematic

About The Circuit

A simple circuit diagram using the TDA 2003 IC is illustrated below. This circuit can be used to make a 10 Watt audio amplifier, and be delivered to a 4 Ohms load at a suplly voltae of 18 Volts. This circuit can also be used for making audio systems in cars by making the circuit be operated in 12 Volts.

For more information about the circuit diagram check out the datasheet of TDA 2003 IC. This IC should be carefully used and must be fitted along with a heat sink for protection. The IC has been designed to provide features like low harmonic distortion, low cross over distortion and also short circuit protection between all pins.

A PCB assembling for this circuit is necessary. A minimum Of 18 volt DC should be used to provide power for this circuit. Amplifier gain is provided by the resistors R2 and R3 whereas C3 and R1 are used to determine the upper cut off frequency. At high frequencies the stability is increased with the help of C6 and R4. Also note down that the input ground and output ground are decoupled. The capacitor C5 is used to couple the output to the speaker.
Circuit Schematic