Max Your idea should work. On the old PS300/390 we did a similar thing to extract a 50/60hz clock signal. A VDE opto-isolator is critical to this design however.
>---------- >From: Max[SMTP:mkel...@chekov.corp.es.com] >Sent: Thursday, January 16, 1997 9:21 AM >To: emc-p...@ieee.org >Subject: Measuring AC > > >Does anyone know of a good method (or have any ideas) of how I could >reduce line voltage down to low (DC) levels in order to measure the line >voltage with an AD converter. > >Using a transformer is obviously the easiest way and probably provides >the least potential problems with safety agencies. But transformers are >not (I don't think) terribly accurate and they are rather bulky even in >this sort of application. > >What are the safety implications, for example, of just rectifying and >filtering the voltage and running it through a voltage divider? > >Thanks, > >Max Kelson >mkel...@es.com >