Mini Amplifier with IC LM1895N
This little amplifier, operating from 3...9 V, and providing 1 W output into a 4 4 loudspeaker, is one of those circuits of which you never have enough. The amplifier is based on one 8-pin DIL IC type LM1895N. Electrolytic capacitors C2 and C6 de- couple the supply lines; C7 prevents d.c. reaching the loudspeaker; and C3 and C5 provide a low- impedance path to earth for audio frequencies. The input signal is applied to pin 4 of the LM1895N via Pi and C4. Resistor R4 and capacitor C8 suppress any tendency to oscillation, i.e., improve the stability. Circuit diagram : Mini Amplifier Circuit Diagram The amplification is determined by Ri and R3: it is of the order of 50. Capacitor C,, in parallel with R,, ensures that the amplification drops off for frequencies above about 20 kHz. If the amplifier is intended for use with a small AM receiver, it is desirable that the amplification starts falling off at a lower frequency. This is brought about by enlarging C,; for instance, if its val...