This is Another a circuit diagram of homemade MIC Speaker Amplifier using LM386. This is small and powerful for at low power supply . This is the Best and interesting circuit for beginner. In this circuit a transistor is used as preamplifier which make input signal noiseless and give input at ic at high gain.
In this circuit the condenser mic become more sensitive that is used to catch the voice signals which i speak . This is Low power Amplifier which can be used at any small and medium size hall, Class Room, Home, office with the 8 ohm speaker.
The power supply required for this amplifier is minimum 4v and maximum 6v for best output result. Use 20k or 10k volume control potentiometer for controlling the voice volume control. Speaker must be connected with an electrolyte capacitor that can be of 100uf-470 uf 25v. Connect a 47nf capacitor between the negative supply and pin 5 with a 10 ohm resistor in series. This is very necessary for noise cancellation. A capacitor between positive and negative supply is connected of 100uf with parallel of 100nf capacitor. The output is boosted and produce powerful sound.
For high sensitivity , Insert condenser microphone in any plastic or metal small box or any cabinet with front open for more sound captcher . External Body is used as sound catching antenna which gives more signal to mic by detecting the vibrations .