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
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
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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