Power Line Noise

[kt88pppamp]

I am having issues both with an analog and microprocessor based circuit where power line noise causes a microprocessor to reset. The same noise causes popping in my tube amp speakers.

The popping comes from the switching of large inductive loads (motors, fluorescent light ballasts, arcing, etc) that kick noise back into the line. The switching regulator (off of a transformer secondary) for the processor does not stop the noise nor does the pi filter in my tube amp work. I have tried inductor/capacitor combinations, metal oxide varistors, and even a voltage suppressor diode in an attempt to filter the noise. None seems to help. The noise when displayed on my scope is arbitrary in amplitude, frequency, and duration. Any ideas on how to stop this? I am not experienced in designing filters to combat such problems.

[kheper]

I have tried inductor/capacitor combinations, metal oxide varistors, and even a voltage suppressor diode in an attempt to filter the noise. None seems to help. The noise when displayed on my scope is arbitrary in amplitude, frequency, and duration. Any ideas on how to stop this? I am not experienced in designing filters to combat such problems.

Simple, AC line filter schematics:

http://links.dalrun.com/Electronics/Doc ... presor.htm

http://mysite.verizon.net/vze22yzp/id11.html

[battradio]

You may need filters on all wiring coming into the microprocessor , the noise could even be induced inside the of the processor mother board and would need an all metal case for it .

[Geek]

Hmmm, give those a try, but it may be more complex than that....

"...switching of large inductive loads..."

A buddy has a place where his line voltage would dive to ~60-65V for a split second as some halogen lights were turned on. The only cure are supplies with stupidly good regulators (like advanced computer SMPS) or in the case of unregged, BIG reservoir caps.

[WA4SWJ]

Not sure what processor you're using, but something else you may think about is the reset line or MCLR line if it is a PIC processor. Perhaps a small capacitor to ground on that line can help. You might be getting reset commands into that line that a capacitor would help prevent. 0.1uF should be enough if that turns out to be the problem. As for the noise getting into the amps the other guys have good suggestions.

Best of luck solving the problem!