Hi u All
i have been working on my intercom which was faulty. I removed....its burnt transformer and the diodes of the rectifier (power supply of the INtercom)....then i had my circuit On but there is a loud BUzz coming out of the speaker(handset)....the LM386 chip is being used. I also changed it because may be it had also blown due to over voltage as it has only 12v absolute rating. I placed a new one...but there is so much noise coming out.....the voice is being amplified it feels..when i remove the 10uF capacitor from pin 1 and 8...... The voice is amplified but there is so much noise that.....it is practically impossible to hear. even when there is no input to the amplifier still it does have the noise. I read all the post on this forums regarding LM386 but could not solve it. I placed ripple capacitor too....for the power supply. i am using a 1uF capacitor at input to block the DC and 220uF at the output of the pin between the pin and the speaker. i even checked at the output pin voltage without input applied..to check whether the chip is blown or not....but it is giving full half voltage of the supply voltage. I checked the current on my Ammeter for the whole this circuit...it came out to be 80mA. this is ridiculous.. according to datasheet of the chip it can only 4mA current....how it is taking 80mA.(this is whole circuit current just including chip and...capacitors and mic only)
if it is blown then why its also amplifying the voice...but with noise. i am really mad about this circuit now.....can anyone help me in this regard. And the circuit for this is very simple....the same given in the data sheet of LM386. Can anyone tell me....whats wrong....? is the chip not right or what?
i have been working on my intercom which was faulty. I removed....its burnt transformer and the diodes of the rectifier (power supply of the INtercom)....then i had my circuit On but there is a loud BUzz coming out of the speaker(handset)....the LM386 chip is being used. I also changed it because may be it had also blown due to over voltage as it has only 12v absolute rating. I placed a new one...but there is so much noise coming out.....the voice is being amplified it feels..when i remove the 10uF capacitor from pin 1 and 8...... The voice is amplified but there is so much noise that.....it is practically impossible to hear. even when there is no input to the amplifier still it does have the noise. I read all the post on this forums regarding LM386 but could not solve it. I placed ripple capacitor too....for the power supply. i am using a 1uF capacitor at input to block the DC and 220uF at the output of the pin between the pin and the speaker. i even checked at the output pin voltage without input applied..to check whether the chip is blown or not....but it is giving full half voltage of the supply voltage. I checked the current on my Ammeter for the whole this circuit...it came out to be 80mA. this is ridiculous.. according to datasheet of the chip it can only 4mA current....how it is taking 80mA.(this is whole circuit current just including chip and...capacitors and mic only)
if it is blown then why its also amplifying the voice...but with noise. i am really mad about this circuit now.....can anyone help me in this regard. And the circuit for this is very simple....the same given in the data sheet of LM386. Can anyone tell me....whats wrong....? is the chip not right or what?