Power hum
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Power hum

 
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Charles
Guest
Posted: Fri Feb 25, 2005 3:42 pm    Post subject: Power hum Reply with quote
Can anyone point me to a circuit for eliminating a 60 cycle power hum.
I have a small transmitter connected to the audio output of my satellite
decoder and want to connect a receiver to the aux input on my Hi-Fi. It
works fine using a 3v battery supply but when connected to a commercial
battery eliminator, there is an unacceptable background hum. I think a need
a filter of sorts.

Thanks
Charles

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Tom Biasi
Guest
Posted: Sat Feb 26, 2005 3:42 am    Post subject: Re: Power hum Reply with quote
"Charles" <ce.mason@telkomsa.net> wrote in message
news:cvnrqt$mdb$1@ctb-nnrp2.saix.net...
Quote:
Can anyone point me to a circuit for eliminating a 60 cycle power hum.
I have a small transmitter connected to the audio output of my satellite
decoder and want to connect a receiver to the aux input on my Hi-Fi. It
works fine using a 3v battery supply but when connected to a commercial
battery eliminator, there is an unacceptable background hum. I think a
need
a filter of sorts.

Thanks
Charles

Correct, you need a filter.

A capacitor across the output may do the trick. You didn't say how much
current you were drawing but given the fact that you said a '3V battery'
you might try a 1000 UF rated 5V or a little more. Make sure the power you
are using is DC and watch the polarity on the cap.
Tom
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kell
Guest
Posted: Fri Mar 04, 2005 6:10 am    Post subject: Re: Power hum Reply with quote
The filter capacitor the other guy mentioned is a good idea. That will
reduce ripple. And another possible source of hum is the rectifying
diodes in the battery eliminator. You can reduce that by connecting a
small capacitor (0.1 or 0.01 uF) across each diode in the bridge.

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