So? Witness the INA163, 100dB+ CMR and PSRR to close to 20kHz at gains of 100, more at higher gains. If your sense resistors are small, which they will be, you need the high gain anyway. Cheers, Jan Didden ----- Original Message ----- From: "Olin Lathrop" To: Sent: Tuesday, July 31, 2001 3:57 PM Subject: Re: [EE]: (Followup) Having difficulty interfacing a current sense resistor to create a proportional voltage > > 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. > > We've been thru this already. Such a setup would require 106dB common mode > rejection to get 1% common mode noise. > > > ******************************************************************** > Olin Lathrop, embedded systems consultant in Littleton Massachusetts > (978) 742-9014, olin@embedinc.com, http://www.embedinc.com > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics