At 12:43 PM 7/31/01 +0200, you wrote:
>If you are cost-sensitive, why not use an instrumentation opamp, some can
>sense diff voltages with 200V+ common mode. The supply (+- 15 v or so) can
>probably be taken from the amp. Must be cheaper, smaller etc than xformer.

Because the CMRR of these amplifiers is nowhere near good enough.

Best regards,
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