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I have a new PC based function generator (very cheap), and an old BK Precision function generator. The old BK Precision can output a signal without the ground or negative reference lead from the BNC cable, but the new PC based function generator can only output a signal when the ground or negative is connected. Why is this? How can I get the new PC based function generator to put out the same signal? I need thins on sided input because the device I'm trying to feed seems to only respond well with the input from the BK Precision unit connected with the "red" lead of the BNC cable connected, and the "black" lead floating.

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  • \$\begingroup\$ Does your BK Precision generator have a 3-wire line chord? Some generators connected BNC ground to the plug ground. \$\endgroup\$ – glen_geek Oct 2 '17 at 19:58
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    \$\begingroup\$ Can you can connect the return on your cheapo gen to frame gnd?? or is this a floating laptop? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Oct 2 '17 at 19:59
  • \$\begingroup\$ You're correct, the BK Precision has a 3-wire line, and the cheap one doesn't. It could be the device is picking up lots of 60hz noise and that's causing my issues? \$\endgroup\$ – MaxHenry Oct 2 '17 at 21:31
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All signal generators need a reference for the signal. Your old sig-gen likely had the output referenced to mains ground while your PC one may be floating.

Assuming, that is, that whatever you are feeding is also referenced to the same ground.

Reliance on the mains ground can be problematic though. Using the reference supplied from the signal generator is much better.

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