The integrated chip LM386 is a low power audio frequency amplifier requiring a low level power supply (most often batteries). It comes in an 8-pin mini-DIP package. The IC is designed to deliver a voltage amplification of 20 without external add-on parts. But this voltage gain can be raised up to 200 (Vu = 200) by adding external parts.
LM386 audio amplifier circuit diagram
The external parts shown on diagram 3.1 can be selected to get the desired gain. Circuit A will give a voltage amplification of 200. Circuit B will give a gain around 50. The circuit C is not for voltage amplification but will raise the bass level by about 5 dB. Take note that the circuit C is to be connected between pins 1 and 5 of the IC.
The power output is around 550 mW at 16 ohm speaker impedance. This audio frequency amplifier is ideal for small battery powered devices.
If you use the external circuit A, replace the Rx with a jumper wire in the PCB.
If you use the external circuit C, solder the additional resistor and capacitor to the PCB points labeled Rt and Cy.
LM386 amplifier PCB and parts placement layout
can it drive 0.5W, 4 ohm speaker
yes, it should be able to drive any single 0.5 watt speaker, but I would add a 10-ohm resistor in series with speaker for safety because the chip is designed for a 16-ohm speaker. I am using am 8-ohm 0.6 watt speaker with a 10-ohm resistor on mine.
send
I m sandy ,can any one tell that what is the use of IC LM386 in multi tome siren ? thaks
I m sandy ,can any one tell that what is the use of IC LM386 in multi tone siren ? thaks
Hi Sandy,
The LM386 is an audio power amp IC that applies much like an operational amplifier. As such, it can be configured as a power oscillator in a siren. Adding switches or clever circuitry makes it multi-tone. Unfortunately, I do not have a schematic.
Jim
Am I correct in assuming that I can use any value for C1 between 47 and 100 mic, and for C4, any value between 220 and 470 mic? Also if I want to add bass boost AND a gain of 50, do I need to modify either circuit B or C when applying them to the main circuit? Thanks for your help.