Hi,

I started building my own music class D amp and it finally started working except that there is a screeching sound over my input signal and I'm looking for the cause of it. it's built on a breadboard so it probably doesn't help, if anyone has ideas of what the problem could be I would be glad to hear them.
thanks

 

Hi,

I started building my own music class D amp and it finally started working except that there is a screeching sound over my input signal and I'm looking for the cause of it. it's built on a breadboard so it probably doesn't help, if anyone has ideas of what the problem could be I would be glad to hear them.
thanks

Screeching implies feedback, like the output is getting into the input. Look for a signal path.

 

so could it be like the grounds are connected from output to input?

 

A schematic would save us a lot of questions. Include the details of your power supply and the load (ie. speaker).

 

Hi,

I started building my own music class D amp and it finally started working except that there is a screeching sound over my input signal and I'm looking for the cause of it. it's built on a breadboard so it probably doesn't help, if anyone has ideas of what the problem could be I would be glad to hear them.
thanks

It's the component layout and or shielding or the output impedance of powers supply is to high. ( motor boating sound)
When your gain goes high input will pick-up and amplify it .( a recursive thing is build)
Breadboard is not the best thing to create amplifiers.

Picbuster

 

I would guess that the breadboard is the problem.

You need a very good ground, the breadboard makes a terrible ground.

 

I would guess that the breadboard is the problem.

You need a very good ground, the breadboard makes a terrible ground.

I agree. That's one reason I asked about the size of the load and the power supply. The power is probably sagging when powering the load, and there's your feedback loop. It may be possible to route the power to the load off-board, including the ground return, and that would help a lot.

 

sorry for my late replie and thanks for the comments I will look into it this week