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kellymarie · 3rd Apr 2021, 4:51 pm

I have a little FM transmitter here which is used to rebroadcast TV sound to my hifi so I can enjoy the better quality and stereo offered by modern TV its powered by a switch mode PSU I got from a charity shop the supply is way over rated current wise so is not strained any way. However there is a 50 cycle hum on the audio which I've noticed disappears when I put y hand on the PSU to unplug it. I noticed that it disappeared like that when I went to move it a while ago its plugged into a short extension lead what do you think why the hum disappear when I put my hand on it??

3rd Apr 2021, 4:51 pm	#1
kellymarie Pentode Join Date: Sep 2020 Location: Weymouth, Dorset, UK. Posts: 135	Odd PSU behavior I have a little FM transmitter here which is used to rebroadcast TV sound to my hifi so I can enjoy the better quality and stereo offered by modern TV its powered by a switch mode PSU I got from a charity shop the supply is way over rated current wise so is not strained any way. However there is a 50 cycle hum on the audio which I've noticed disappears when I put y hand on the PSU to unplug it. I noticed that it disappeared like that when I went to move it a while ago its plugged into a short extension lead what do you think why the hum disappear when I put my hand on it??