So I kinda shot myself in the foot by purchasing a two prong wall wart to power an audio preamplifier that I designed. I forgot to consider the fact that I should ground my chassis to the earth connection via a three prong AC plug. Does anyone know a way I can ground my chassis while still using the two prong wall wart? I was considering modifying the wall wart by adding an additional discrete prong on top of it that would plug into the earth connection of an outlet. If you think that I can get away with leaving my chassis floating, please let me know as well. Thanks.
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\$\begingroup\$ Lots of audio equipment nowadays has no ground connection and works fine without it. \$\endgroup\$– FinbarrCommented Dec 1, 2020 at 21:17
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\$\begingroup\$ What is the purpose of the connecting the ground of your chassis to the earth? \$\endgroup\$– D DuckCommented Dec 1, 2020 at 21:56
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1\$\begingroup\$ It would be fairly normal to ground the power amp to AC, and ground the preamp via the audio cables to the power amp. \$\endgroup\$– user16324Commented Dec 1, 2020 at 23:01
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\$\begingroup\$ I doubt it with the wall wart but just to check: is this a vacuum tube preamp? I.e.: do you have 230V plate supply running around in there? \$\endgroup\$– virCommented Dec 1, 2020 at 23:44
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\$\begingroup\$ No, the entire thing is op amp based since I am on a budget for class. No vacuum tubes, no isolation transformers, nada. And the purpose (for D Duck) of connecting chassis to the earth connection is so that there is a non-audio return path for any induced noise and for electrical safety \$\endgroup\$– Gus the BusCommented Dec 3, 2020 at 17:02
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3 Answers
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wanted to let you know that I found a solution. I cracked open the wall wart and took out the circuit. I took an AC plug and wired the live and neutral together and then used the earth connection for the chassis. Thanks for your responses
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A ring terminal to the faceplate mounting screw on the outlet and connected to a convenient screw on the chassis is probably the easiest and safest way to do that.
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The best thing to do would be to purchase a power supply with a ground terminal. Modifying a wall wart could potentially make it unsafe. It's really up to the application to see if it needs grounding, many applications don't need it. Audio does not need a DC ground and in many cases a ground usually makes ground loops. Usually chassis ground is for safety reasons. In the event of a fault of AC mains, current returns to ground instead of shocking someone.
If you really do need a ground, you could add one with a second cable for prototyping purposes. There are cables available (from amazon) that have only a ground clip and 3 prongs.
answered Dec 1, 2020 at 21:52