I know there was a device made by Siemens that did just that in one package and if you where going to do it this way I think it might be worth looking at. There will be app notes there too. However, I think for long term stability it might be better to do it another way, maybe a V to F, opto and then a F to V converter, or another technique we used was to transfer a current signal through a transformer, using the same transformer to power the other side. If you want to look more into this the guy who pioneered this is here: stewartclan@xtra.co.nz (Gordon Stewart) Send him an email, I'm sure he can help. ----- Original Message ----- From: "Wouter van Ooijen" To: Sent: Saturday, July 19, 2003 8:44 PM Subject: [EE]: analog isolation using double opto-coupler > I want to convert a 4-20mA signal to RS-232, with isolation. My first > idea would be to put the isolation between the 4-20mA and the A/D, > using a double optocoupler (second one used to linearise the first one). > Do you know what accuracy can be achieved with this setup, or any links > to app notes? > > Wouter van Ooijen > > -- ------------------------------------------- > Van Ooijen Technische Informatica: www.voti.nl > consultancy, development, PICmicro products > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body