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I'm building a simple function generator powered from a 24V AC wall adapter. I've rectified the incoming AC to 24V DC using a full wave bridge and an LM317. I intend to split the supply into +/-12V rails with a virtual circuit ground (see image below).

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My BNC connectors need grounding and my idea is to ground the chassis to circuit ground as shown in the diagram. Are there any problems doing this? More specifically, are there any safety issues and will it cut down on interference? The point where the circuit ground (from the supply board) meets the chassis will also be a star-ground point for all grounds in the system.

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Generally speaking, you would connect the circuit ground (which is your virtual earth point) to the chassis. The BNC connectors are also usually connected to the chassis.

Because this is a signal generator, I would NOT connect the chassis to an external Earth ground to help avoid ground loops. Because you are using a wall-wart transformer as your power supply, this is an easy decsision.

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  • \$\begingroup\$ Great. That's what I thought - best to make sure. \$\endgroup\$
    – Buck8pe
    Aug 28, 2015 at 17:26
  • \$\begingroup\$ Since your device it is not on an isolated environment, earth can be transferred by another device connected to this. A total (AC-DC) earth design it is necessary. \$\endgroup\$
    – GR Tech
    Aug 29, 2015 at 4:15

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