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amplifier hum


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Good day...i have build your 200W audio amplifier and it work well.
but when i connect it to my tape deck and touch the chassis it is humming why?
I could not get 150nf or 1.8nf ,so i put in 0.15uf ceramic cap for
150nf and .0018uf for 1.8nf and it work. but why the humming please

Project Link: http://www.electronics-lab.com/projects/audio/013/index.html


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:)hi there,

you mentioned you used ceramic caps, try replacing those with mylars or polypropylene caps.

there are several sources of hum in an amplifier,
1. poor grounding connection
2. defective capacitors
3. inadequate power supply filter
4. poor ground line lay-out
5. ground line loop
6. external input hum

Quest. 1. on a stand alone, meaning no signal input, do you hear any hum from your amp?
Quest. 2. does your input ground share the same line with your power line ground?

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  • 2 years later...

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