--=======AVGMAIL-41FE0B411C00======= Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Actually, my original post is dated 1/6/2005, at least according to my email logs. I've also been extremely busy this last month, and I've been having some stupid problems with sending out emails to this listserver... I wasn't asking for anyone to out and out design it for me at that time, so there was no need to give detailed specs. But of course, people on this listserver seem to have an unholy obsession with SMPS's, so next thing ya know, everyone's telling me to make a SMPS, and me saying "tried it, don't work", back and forth, etc, etc.... As I've already said, more than once, this is a different type of AC Phase control (NOT SMPS). Was asking how to set up the mosfets to do this (do I need free wheeling diodes, etc?), maybe get an idea what values I would need for inductors, figuring out how to run the PWM frequency high enough but still use a pic to control the darned thing. Yea, I'm aware that I loose upwards of half the power in the cord alone. Not much can be done about that. Can't make it shorter, Silver is too expensive, and I can't use car battery cables... Did I mention that it's a high quality, high stranding, oxygen free copper cord? ;-) Don't worry about it, I just want to try a different type of gas in my "engine", not totally re-invent the wheel, the engine, or the whole car for that matter. Well, that was the first basic question I asked. Here, I'll quote from my original email: Only big problem I've seen for doing this circuit so far, is being able to generate a 48khz+ PWM using a PIC with fine enough resolution (I'd prefer 10 bit resolution, especially if you want to do the universal input). Any simple/easy/cheap way to do that trick with a PIC? Is there a SMPS control chip circuit that could be modified or tricked to do this (and could be controlled via a PIC)? QUESTION ASKED! NEVER ANSWERED! We all went off on the SMPS tangent instead. Could you use some sort of frequency doubler or quadrupler. Can a standard PIC's hardware PWM be sync'd to a different frequency than what the rest of the uP is using? Or do I need to just go out and get some sort of stand alone hardware PWM that is controlled with DC input? Any suggestions? Is this spelled out enough? What part of these questions am I not making clear here? Just like when people here say RTFM, you first have to RTOFP 8^] That last paragraph you quoted is not a question at all (I don't see even one ? in it). It's more of a plea for people to get off of the SMPS kick, and get back to what I was originally asking about. I've been very persistent in asking for help, but now I'm starting to see why I see a lot of one time posts from people who are never heard from again on this listserver. So far it's been kind of like asking how to get a sharper knife edge, and being told that I should go out and get a chain saw instead (by the listserver's ample supply of chain saw enthusiasts and dealers).... Dave Tweed wrote: >"Bob S." wrote: > > >>Thanks Russell. I didn't understand myself why Olin was even talking >>about that. Boy, people just love to go off on tangents that have >>little or nothing to do with what the original post was about >>(explaination below). >> >> > >Indeed. Such are the consequences of asking a bad question. It's only >taken us 31 days (your original post was on Dec. 30) to get the *real* >requirements of your application, and a clue about the things you've >already tried. If you had presented this information up front, it would >have saved everyone a lot of time and anguish. > > > >>Normally the power has to travel through a 4 foot 16 Gauge cord >> >> > >That's about 32 milliohms right there, almost half of your 80-milliohm >working load. And that's not even considering the connectors in the >path. But I guess you've worked all of that out and are satisfied with >the results. > >Anyway, we're back where we started, which was you asking: > > > >>Only big problem I've seen for doing this circuit so far, is being >>able to generate a 48khz+ PWM using a PIC with fine enough resolution >>(I'd prefer 10 bit resolution, especially if you want to do the >>universal input). Any simple/easy/cheap way to do that trick with a >>PIC? Is there a SMPS control chip circuit that could be modified or >>tricked to do this (and could be controlled via a PIC)? >> >> > >And now you're asking: > > > >>I would appreciate it if someone here would help me investigate >>PWM AC Phase control (AKA Sinewave Phase control), and not try to >>steer me like some idiot sheep towards building a SMPS (already >>tried it, doesn't work, end of story!). SMPS's are not the "end >>all - be all" design for every application! This is a new kind >>of AC phase control method (not forward or reverse PC), so at the >>very least it would be a learning experience for anyone looking >>into it. >> >> > >Spell it out for us: Have you tried generating the 48 kHz 10-bit PWM >by any means at all (ignoring a cheap PIC-based imnplementation for >the moment) and were you satisfied with the results? It now appears >that you're asking someone else to do that investigation for you. > >-- Dave Tweed > > --=======AVGMAIL-41FE0B411C00======= Content-Type: text/plain; x-avg=cert; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Content-Description: "AVG certification" No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.2 - Release Date: 1/28/2005 --=======AVGMAIL-41FE0B411C00======= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=======AVGMAIL-41FE0B411C00=======--