[TechAssist] Re: use a battery backup UPS for TV,DVD,surround amp system protection ?

  • From: gulftech@xxxxxxxx
  • To: techassist@xxxxxxxxxxxxx
  • Date: Sat, 8 May 2004 18:45:01 -0500

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
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>
> > >>>
> >
> >
> >
> > 
>
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