Quoting Dave Dilatush : > Oliver Broad wrote... > > >I think I see what's going on, maybe... > > > >There's no smoothing capacitor in your diagram. I bet there's a reasonable > >smoothing cap on the input of the regulator circuit though. > > I have only the smoothing cap that the maxim site recommends (220uf) > >When you measure without the regulator you measure the average of the > >rectified waveform, which is still dipping down to zero between each half > >cycle so you measure a lot less than peak, possibly less than RMS even? > > > >When you connect the regulator there's a capacitor present so it > >peak-detects and reads >50% higher. This is the relevant reading. If this > is > >too high you have the wrong transformer. > > Duh. Why didn't I think of that... > > That's exactly what's going on, I'm sure of it. > > Jai, if you are intending to get +5V and +12V out of this power > supply, there is no need for you to be using a transformer which > puts out so much voltage. Instead of 50 volts center-tapped, I > think 28 volts center-tapped would suffice. That would give you > around 18-20 VDC at the input to the regulators. > You are absolutely right - I don't need a xformer that powerful. The problem was the surplus store only carried that type at the time. this is used of course, new xformers are sooo expensive that I didn't want to fork out that much just for this. Obviously, the better solution would be to wait until they get more in (Which they will) and use a more appropriate xformer. But anyway, your explanation makes perfect sense to me, thank you sooo much!! I actually understand why now. I appreciate all your help! > DD > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > ---------------------------------------- This mail sent through www.mywaterloo.ca -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body