Hi Dave and ALL! On Sat, 5 Apr 2003, Dave Tweed wrote: > This has two implications. First, although the RC time constant is the > same in either case, it takes a fixed amount of additional time to reach > a particular voltage compared to returning it to +5V. The second thing > only have resistance, the switches can also become nonlinear, saturating > at a fixed amount of current. This extends the charging time even further. > So overall, in the interest of getting faster startup and recovery from > transient loads by avoiding saturation effects in the switches, I think > it would be better to connect the bottom end of the +10V filter capacitor > to the +5V supply. I am not an analog geek. At all. I can make almost any basically cookbook/data-sheet-standard stuff work if necessary but nothing beyond that. I am not a serial geek, but I know how to get things running if they're 'supposed' to work. I've seen slight reference to the topic of polarized vs nonpolarized but nothing definitive. Yours seems to talk about *time* more than others which is the issue I have right now. Software. Using PICUSART to learn serial. Using Tera Term at the other end to talk/monitor. Everything worked on the first try in both directions at 115k. Hardware. Using PICDEM2, has MAX232ACPE, has non-polarized caps on +5, C1/C2, and V+/V-. They're the right value but not the recommended type. That is what concerns me because at higher speeds I get lots of errors and at medium speeds I get no (zero) errors. Of course http://pdfserv.maxim-ic.com/arpdf/MAX220-MAX249.pdf page 17 shows polarized caps all around. I'm sending and logging screens of about 2.5k of hello world text, about 80 chars plus CRLF, about 30x to fill a screen. Then a counter so I know how long it's running. (Plus a blinkie-counter just in case the term messes up I want to see that the PIC is still running.) Then an ANSI 'clear screen and home cursor.' During these tests not doing any 'reading' at the PIC side, not even calling the input subroutine, just blasting text out to take one possibility of problem of the list. At 115k the first line *always* drops several of chars *before* the first CRLF. Never the same chars. The rest of the screen is almost always flawless, drops a few here and there, only about 2-3% of full screens have an error. But I can induce a few more drops by making Win 'do something' such as switching to other windows. I can see behind what I switch to that chars are dropped, and capture to log to make sure they really are dropped. Overall is obviously not working well. At 57k I grab 250k worth of log and -sometimes- there're a few dropped chars. Not always, even 'trying' to load the system to induce them. At 38k I grabbed 500k while doing several windows Find searches, reading email, 'cat'ting a few meg through PuTTY, and using a text editor in a DOS box. The drive, screen, and system in general was doing a lot of stuff but the capture was -perfect-. So the Q is whether it's *remotely* *possible* that these nonpolariZed caps could cause these errors? I don't want to change them if it's less than likely to fix anything; I'd chalk it up to Win and live with the 38k. Tnx and have a :) day! jb -- jim barchuk jb@jbarchuk.com -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu