Certainly, the inverters can run that low, but if so they sing a lot. Best,
-John ================= > John, > > I didn't mean to say you said all that, just that the new inverters are > cheap. I wrote that I thought some ran at around 1 kHZ, as I had an old > one > that did, and used a toroidal transformer in it. The new ones, as far as I > am aware, are similar to the new-style switching power supplies, like the > ones Maxim and a few others show in their app notes. > > Best, > > Will > > *********** REPLY SEPARATOR *********** > > On 6/25/2011 at 12:37 PM J. Forster wrote: > >>> Chris, >> >>No I didn't say the output was 1000 Hz. No way. >> >>What I said (a bit amplified) was that the cheapie inverters use a high >>frequency, think 50 KHzish, DC-DC converter to make about 170 VDC, then >>use that to feed an "H" bridge, driven with either a square wave or a >>modified square wave, to make the output. You snmply need to vary that >>drive frequency to get 50, or 60, or any frequency you want. >> >>There is no output transformer. In fact, that is the cleverness of the >>design... no big, heavy, expensive magnetics. >> >>-John >> >>=================== >> >>> As John mentioned earlier, the el-cheapo inverters are pretty much >>> junk, and run as high as 1 kHz, if I recall. They were made to run >>> small >>> TV's, etc, that don't require a fixed line frequency, since they all > have >>> hot chassis now that don't use isolation transformers. >>> >>> Best, >>> >>> Will >>> >>> *********** REPLY SEPARATOR *********** >>> >>> On 6/25/2011 at 11:55 AM Chris Albertson wrote: >>> >>>>> The reason for using 12 Vdc, is that you can pick them up, and 24 Vac >>>>> CT >>>>> transformer, on the cheap >>>> >>>>That's a good point. So use two of them. One to power a high >>>>current amp that produces a 12V AC signal from a high precision 60Hz >>>>input. Then the other to convert the 12V to 120V. This avoids the >>>>need for a high voltage DC power supply. Likely cuts the total cost >>>>in half at least. So just use use 12V supply to the amp and then a >>>>cheap 12V transformer connected "backwards" to step up to the desired >>>>voltage. >>>> >>>>The second advantage of this design is that you can connect a lead >>>>acid gell cell battery in parallel to the 12V DC supply and if the AC >>>>fails the battery will power the amp for a while. This way there is >>>>no switching so the 60Hz wave remains continuously even if AC mains >>>>fails. >>>> >>>>This is something most UPS don't do but for this application you don't >>>>want the 60Hz sine wave to be broken. >>>> >>>>As long as the load is only a few milliamps of AC this should not be >>>>hard to do. >>>> >>>> >>>>-- >>>> >>>>Chris Albertson >>>>Redondo Beach, California >> >> >> >>__________ Information from ESET Smart Security, version of virus > signature database 5851 (20110206) __________ >> >>The message was checked by ESET Smart Security. >> >>http://www.eset.com > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
