Audio circuits
Improved 3 Transistor Audio Amp
The load resistor for the driver transistor is tied directly to the + supply. This has a disadvantage in that as the output moves positive, the drop across the 470 ohm resistor decreases which reduces the base current to the top NPN transistor. Thus the output cannot move all the way to the + supply [...]
LA4555 Audio Amplifier
Stereo circuit and mono circuit are given in schematic .LA 4555 is basically a stereo amplifier with 2.3 watts into 4 ohms speakers at a total distortion of 10%. With a bridge circuit, it can be configured as mono amplifier delivering 4.6 watts. It has an input impedance of 30K and gain of 51 dB. [...]
Door Phone
LM 386 is just right for a door phone application. It is very useful application in the present urban households. One condenser microphone and a speaker are kept conveniently outside and another set with amplifier are kept inside. With a door phone installed at the main door, it will be easy to recognize the caller [...]
LM 386 Audio Amplifier
LM386 is one of the earliest audio ICs but is still going strong. It works with a few external components and is indispensable for general hobby circuits where audio amplifier of low power is needed. It is mini audio power amplifier which would prove essential as a test amplifier for solving typical problems in the [...]
Preamplifier with LA3161
Preamplifiers are used to amplify low level signals such as those from mikes, tape heads before they are fed into power amplifiers. Power amplifiers are generally less sensitive. Frequency response also can be suitably trimmed and modified at preamp stage. LA 3161 is one of those widely used in tape decks and amplifiers as a [...]
A Collar Mike
Microphone is added here for the very use it has, and by the ease of making one. It can be used as a good quality microphone. Here is a simple circuit that makes the condenser mikes work, which can also be used as a collar mike. Condenser mikes are rugged, have excellent frequency response, and [...]
