single supply op-amp rectifier

i need to rework a LM358 opamp based recision rectifier from a split

+/- 5v supply to a single ended supply. i biased the non-invert input to half supply volts using a voltage divider. the feed is the secondary of a CT. for symmetry i would think that i still connect the secondary of the CT to the same points in the circuit (do i need to capicitive couple?i didn't b4). Also I would think thet the output ma meter would be placed between o/p pin and ground...or should this also be between the output and the noninvert pin bias voltage. many thx.
Reply to
Danny
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You need to use resistors etc to make the bias points. The time constants only depend on the capacitors and resistors that interact.

Go get yourself a copy of LTSpice AKA SwitcherCad-3 from

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and try modeling the circuit.

Reply to
MooseFET

What kind of rectifier is it, inverting, non-inverting, full-wave, half-wave, how much current is that milliammeter sinking, and what frequencies are you working with? Generally, very little reworking is required. Take a look at your schematic, then everywhere you show GND, pencil in VGND for Virtual GND, and where you have -5V, pencil in GND, this now your new physical Ground. The VGND is usually, but not necessarily, half the single supply voltage or Vsupply/2. In order to avoid problems with DC offsets in a precision circuit, this is usually produced by a single circuit at a single node and then distributed to all the VGND nodes in the circuit, and that single circuit usually consists of a resistor voltage divider between Vsupply and GND buffered by an opamp with heavily bypassed output for decoupling.

Reply to
Fred Bloggs

Does your ISP charge you by the letter? Or more for Capitals than smalls? What the hell is a CT? My ma doesn't have a meter. Pa does, though.

Jim

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Reply to
RST Engineering (jw)

Jim,

CT is a current transformer. ma=3DmA. Thanks for your corrections.

Daniel

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Reply to
Danny

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Daniel,

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Reply to
John Fields

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