68Views2Replies

Author Options:

Can anyone help me troubleshoot my amp? Answered

I recently built an amp using lm386 ic. It works really well but it makes a buzzing sound while playing and while ideal with no input and power on.

Comments

The forums are retiring in 2021 and are now closed for new topics and comments.
0
framistan
framistan

8 years ago

Place an electrolytic capacitor across the power source ... 470 uF should do it. Be sure to use a capacitor of sufficient voltage rating to withstand whatever you connect it to... and observe polarity of the capacitor (plus to plus... minus to minus). See if the buzzing sound decreases or goes away. If it goes away, then it was caused by your power supply not producing a pure DC voltage. If you are using a battery, then that IS A PURE DC voltage source and on to the next idea..

It could be your input signal is very low... this will cause you to turn up the volume all the way on your LM386. All amplifiers have some noise, and when you turn up the volume all the way, you are going to hear it. The solution here is to increase the signal level coming INTO the lm386. That will allow you to turn down the volume on your LM386 and the buzzing will be reduced.

Another problem could be the construction of the LM386. If you built it in a plastic box with no shielding around it... you may pick up some stray noise such as fluorescent lights. The fix for this is to build the LM386 inside a metal box ... which might fix your problem.

Another problem is you may be just trying to crank up the volume too far. The LM386 is not very powerfull and maybe you expect too much out of it by turning it up too loud. In this case, you maybe need a bigger amplifier.

0
steveastrouk
steveastrouk

8 years ago

What kind of PSU did you use ?
Sounds like either PSU noise injection, or a earth loop.

Show your circuit, and a picture of the wired amp.