Come on Jerry, Since when is a square wave referred to as RMS? That is only applied to normal AC of some given frequency. I would agree that a zero to +115 volt square wave would result in 115VDC output, but as far as ripple--you got to be kidding. That would be a 50% duty cycle, fed into a conventional bridge assuming no leakage. It would also result in a higher than normal current for the diodes of the bridge. Feeding 120 VAC 60Hz, the peak is (indeed) 169.68 volts. (1.414 x 120.) But, a square wave, 0-120, results in just 120 volts less decay time during non-conduction, with much less need for filtering. Now, if the input were to be a -60 to +60 square wave, the result would still be the same. I have too much respect for your input not to challenge your statement. You said "Transformers designed for 60 Hertz will run hotter when fed a square wave." Not true. The avg. current of a sine wave input is only 63%. A square wave is either on or off. That means 50%. Now, even if the square wave was +/- 60 vdc, the average current would STILL BE LESS than 120v RMS. I don't often pick a problem with your posts. You are a person I respect. However, I disagree with your statement. I certainly stand to be wrong. It wouldn't be the first time, but according to theory, whether it be 0-120 V RMS or -60-+60 square wave, will produce the same average current. The peak voltages would be of course different. Given the separate inputs, 120 VAC to a bridge gives 169 volts peak. A square wave 120 dc input yeilds only 120 volts output, with lesser need for filtering. This is, of course, neglecting the diode drop. I don't know how this would affect equipment connected to a backup. I don't mean to keep this for discussion. I personally feel that comparing computers to amplifiers for a load is not possible. The computer load is fairly constant, but the amplifier load is not. The current draw on a computer is fairly constant. That of an amp is dependent on both the source and the volume level selected. I would suggest that the peak of power required for an amp would be much higher than for a computer/monitor. My apologies to Jay, the other TechAssist staff, and to those of you who could care less. I don't mean to imply that this question has no merit. It does. It gives all of us a chance to discuss the basics of our trade. I spent years teaching this stuff, but I have been wrong before. Just don't stop trying to learn. Ken Smith Gulf Technical Services 3034 Gulf Breeze Parkway Gulf Breeze, FL 32563 850-934-8324 (Voice) 850-932-0819 (Fax) On Fri, 7 May 2004 17:38:51 -0400 "J Silverman" <greentron@xxxxxxx> writes: > If you have a 115 volt RMS square wave and rectify it and filter it, > you > will get approx 115 VDC and practically no ripple. If you rectify > and filter > a 115 volt RMS sine wave you will get about 162 VDC and ripple > depending on > load. Transformers designed for 60 Hertz will run hotter when fed a > square > wave. Thinner laminations are used if the transformer has to handle > higher > frequencies. Also the magnetron high voltage in a microwave is > developed > using a 60 Hertz transformer with a resonating capacitor, selected to > resonate with the leakage inductance of the transformer. If you want > to > change power sources for equipment, you have to keep these things in > mind. > Jerry Silverman > Greentron Inc > 4 Newland Ave > Greenville SC 29609 > 864 232 3889 > Fax 271 2080 > mailto:greentron@xxxxxxx > ----- Original Message ----- > From: "Ty" <ty1k@xxxxxxxxxxx> > To: <techassist@xxxxxxxxxxxxx> > Sent: Friday, May 07, 2004 4:23 PM > Subject: [TechAssist] Re: use a battery backup UPS for > TV,DVD,surround amp > system protection ? > > > > This question has me intrigued. Why is it being debated by > proficient > > electronic technicians? > > OK. MODERN televisions, VCRs, DVDs, anything with a pulse power > supply. > > Reasoning that modern Pulse Power supplies essentially run on DC, > I was > > wondering what difference it makes what kind of sign, square, or > whatever, > > wave gets rectified in order to charge the primary filter > capacitor. As > long > > as the filter is charged to the critical starting voltage and is > maintained. > > Of course, you will have to raise the input to meet the output > criteria. > > Heck, you can use DC for input and you can even ignore the > polarity due to > > the bridge!. > > Mmmmm.... > > Take a voltage reading on the main filter cap under full load. > > Connect a bunch of batteries to attain the voltage. Connect it > across the > > filter and you got your problem solved. Instant UPS. Of course, > you will > > have to modify the ON/OFF switch. Another problem is charging > inrush. Use > a > > diode and resistor combination. Heck, we can figure it out! > > Now the 10 lb transformer in a power amplifier or in the Microwave > is > > another story, but not impossible if batteries are used after the > > transformer. Storage would be a problem. Where would you store > enough > > batteries to power a Magnetron and finish cooking that turkey. > > Lets see. Move the holyday dishes to the basement, move the > regular dishes > > to where the holyday dishes were, and WALLA! LOOK OUT TURKEY! > > Just realized the biggest obstacle to my simple idea. How am I > going to > get > > the wife to allow me to drill a hole in the countertop... > > > > Have fun! >(;o) > > > > Ty > > > > Tiberius Kraemer > > BLUE STAR ELECTRONICS > > 3312 Silverton Rd. NE > > Salem, Oregon > > Phone: 503 391 1491 > > Mailto:ty1k@xxxxxxxxxxx > > > > > > > > -----Original Message----- > > From: techassist-bounce@xxxxxxxxxxxxx > > [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of Phil Bader > > Sent: Friday, May 07, 2004 11:44 AM > > To: techassist@xxxxxxxxxxxxx > > Subject: [TechAssist] Re: use a battery backup UPS for > TV,DVD,surround > > amp system protection ? > > > > > > Shoot, jerry why are your facts so depressing! > > Seriously, I called APC, and the tech said the "stepped sine wave" > > versions may not work satisfactorily with , say, an engraving > machine > > (My next door neighbor has a trophy shop). he suggested their > better > > Smart UPS line, I think its called.Anyway, it would be sort of self > > defeating to destroy the very thing you are wanting to protect... > > Phil Bader > > > > J Silverman wrote: > > > > >The computer power supplies work fine with the 115 VAC (RMS) > square wave > > >output from the low cost UPSs. Most consumer electronic equipment > is > rated > > >for 115 volt RMS 60 Hertz sine wave, plus or minus 10%. If you > use the > > >computer UPS with consumer electronic equipment the internal > voltages and > > >losses are different than the spec., so you are not sure if you > will have > > >functional problems or if things will overheat. A lot of stuff > will > > probably > > >work OK, but you cant be sure. So the suggestion was made to use > UPSs > that > > >have a sine wave output and these are many times more expensive > than the > > >ones with a square wave output. > > > > > >Jerry Silverman > > >Greentron Inc > > >4 Newland Ave > > >Greenville SC 29609 > > >864 232 3889 > > >Fax 271 2080 > > >mailto:greentron@xxxxxxx > > >----- Original Message ----- > > >From: "Kevin" <kevintv@xxxxxxx> > > >To: <techassist@xxxxxxxxxxxxx> > > >Sent: Friday, May 07, 2004 5:30 AM > > >Subject: [TechAssist] Re: use a battery backup UPS for > TV,DVD,surround > amp > > >system protection ? > > > > > > > > > > > > > > >>Using a UPS for a computer is also designed to save what a > person is > > >>working on at the time of a power outage. When the power goes > out the > > >>computer stays on and the person can save his work and then shut > the > > >>computer down properly. In some cases it will also prevent data > from > > >>being corrupted on the hard drive when the power goes out. > Having the > > >>power outage causes windows to shut down improperly, which could > corrupt > > >>data on the hard drive. > > >> > > >>Kevin Wilks > > >>Kevin's TV & Video Repair > > >>Penticton BC Canada > > >>kevintv@xxxxxxx > > >> > > >> > > >>-----Original Message----- > > >>From: techassist-bounce@xxxxxxxxxxxxx > > >>[mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of Hoyt's TV > > >>Sent: Friday, April 30, 2004 2:11 PM > > >>To: techassist@xxxxxxxxxxxxx > > >>Subject: [TechAssist] Re: use a battery backup UPS for > TV,DVD,surround > > >>amp system protection ? > > >> > > >>Considering the price of some TVs and stereos these days, I'm > surprised > > >>they > > >>don't push UPS's for those, like they do for computers. > Computers were > > >>the > > >>first things that were overly sensitive but TVs etc. have now > caught up. > > >> > > >> > > >>Russ Hoyt > > >>Hoyt's TV > > >>Exeter, NH > > >> > > >> > > >>----- Original Message ----- > > >>From: "Larry Poffen" <lpoffen@xxxxxxx> > > >>To: <techassist@xxxxxxxxxxxxx> > > >>Sent: Friday, April 30, 2004 3:46 PM > > >>Subject: [TechAssist] Re: use a battery backup UPS for > TV,DVD,surround > > >>amp > > >>system protection ? > > >> > > >> > > >> > > >> > > >>>I have used a APC 1000 for my personal stuff for about 2 years. > I had > > >>> > > >>> > > >>a > > >> > > >> > > >>>power surge that took it out this year, along with many other > things, > > >>> > > >>> > > >>but > > >>my > > >> > > >> > > >>>36" TV &VCR/ stereo stuff were all OK. It is worth the peace > of > > >>> > > >>> > > >>mind. > > >> > > >> > > >>>Larry > > >>> > > >>>Larrys TV Service > > >>>Broken Arrow OK 74011 > > >>>phone 918-455-1041 > > >>>Fax 918-451-4485 > > >>>e-mail lpoffen@xxxxxxx > > >>>----- Original Message ----- > > >>>From: "Phil Bader" <tjanphyl@xxxxxxxxxxxxxxx> > > >>>To: <techassist@xxxxxxxxxxxxx> > > >>>Sent: Friday, April 30, 2004 9:06 AM > > >>>Subject: [TechAssist] use a battery backup UPS for > TV,DVD,surround amp > > >>>system protection ? > > >>> > > >>> > > >>> > > >>> > > >>>>I never heard of anyone doing this, but I've had this thought > for a > > >>>> > > >>>> > > >>few > > >> > > >> > > >>>>years: > > >>>>use a heavy battery back up UPS like used on PC systems for an > > >>>>entertainment center. Many ills are from power > > >>>>fluctuations,sags,surges,etc. TV EEPROMs corrupted, power > supplies > > >>>>damaged, pro-jo CRTs damaged with a spot because it went down > at > > >>>> > > >>>> > > >>once > > >> > > >> > > >>>>without proper power down,etc. > > >>>>Most equipement is not a heavy current draw. > > >>>>Can this be done and should it? > > >>>>I have a Zenith 50" projection TV (not wide screen,standard > 3:4) > > >>>> > > >>>> > > >>which > > >> > > >> > > >>>>is rated at 215 watts (2.8A) "max". > > >>>> I think my VCR/DVD deck pulls maybe 30 watts. > > >>>>My Bose "lifestyle 7" surround amp, I don't know the wattage. > > >>>>And a cable box maybe another 30 watts? > > >>>>I'm guessing 300-400 watts max running everything > > >>>> if using the sound system as well. Much less if using only the > > >>>> > > >>>> > > >>projo's > > >> > > >> > > >>>>speakers. > > >>>>Now most of these UPS units are in standby mode and the > connected > > >>>> > > >>>> > > >>gear > > >> > > >> > > >>>>is running off line current until there is a power loss, which > time > > >>>>ultra-fast switching transferrs power to the battery system. > This > > >>>> > > >>>> > > >>would > > >> > > >> > > >>>>be only needed for intermittant power fluctuations, or if lost > > >>>> > > >>>> > > >>totally, > > >> > > >> > > >>>>enough time to safely power off the audio/video system. > > >>>>A 6 outlet power strip plugged into the UPS would be > convenient. > > >>>>What would be a good power rating for a UPS? > > >>>>Twice needed wattage? whats rule of thumb, and also whats your > > >>>> > > >>>> > > >>feedback > > >> > > >> > > >>>>on this idea? > > >>>>Phil Bader > > >>>> > > >>>>-- > > >>>> > > >>>>Philip Bader > > >>>>Jan Phyl TV Inc. (estab. 1976) > > >>>>3420 Recker Hwy. Winter Haven, Fl. 33880 > > >>>>Fax (863) 299-8821 > > >>>>email: tjanphyl@xxxxxxxxxxxxxxx > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> > > >>> > > >>> > > > > > > > > > ------------------------------------------------------------------------- - > -- > > - > > Lost Password: > > http://www.tech-assist.org and select "Login Problems?". > > Email Archives: > > //www.freelists.org/archives/techassist/ > > > > > > > ------------------------------------------------------------------------- - > --- > > Lost Password: > > http://www.tech-assist.org and select "Login Problems?". > > Email Archives: > > //www.freelists.org/archives/techassist/ > > > ------------------------------------------------------------------------- ---- > Lost Password: > http://www.tech-assist.org and select "Login Problems?". > Email Archives: > //www.freelists.org/archives/techassist/ > ________________________________________________________________ The best thing to hit the Internet in years - Juno SpeedBand! 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