motteler@umbc3.UMBC.EDU (Howard E. Motteler) (03/21/90)
Does anyone know how the 3b1 power supply holds up when fed the square wave output typical of most UPS's? I know this causes a problem for some switching power supplies. Any favorite brands? I see James Electronics is selling a 200w "trip-lite" brand UPS for about $240, and for a while, ERAC was selling 400 watt Elgars, with "cosmetic defects" for only $180. -- Howard E. Motteler | Dept. of Computer Science motteler@umbc3.umbc.edu | UMBC, Catonsville, MD 21228
elliot@alfred.orl.fl.us (Elliot Dierksen) (03/22/90)
In article <3005@umbc3.UMBC.EDU>, motteler@umbc3.UMBC.EDU (Howard E. Motteler) writes: > > Does anyone know how the 3b1 power supply holds up when fed the square > wave output typical of most UPS's? I know this causes a problem for > some switching power supplies. > Any favorite brands? I see James Electronics is selling a 200w > "trip-lite" brand UPS for about $240, and for a while, ERAC was > selling 400 watt Elgars, with "cosmetic defects" for only $180. I have a UPS for my system which uses a modified sinewave output and it works just fine. It is American Power Conversion 450AT which has a switching time of 1 millisecond. It was recommended to me by name from somebody at the Hotline. He had worked for a VAR that sold 3B1's and they used those with every system and he said they never had a problem. I got mine from Computer Discounter's Warehouse. They are listed in Computer Shopper and it was about $330 for it. 450 watts by the way. Usual disclaimer, I only bought something from CDW and APC that I like, I have no other connection with either firm. Hope this helps!!! EBD -- Elliot Dierksen "I don't care if my lettuce has DDT on it, as long as it's crisp!!" -- Jorma Kaukonen Work) {att,codas}!candi!fang!ebd (407) 660-3377 Home) {peora,uunet,ucf-cs}!tarpit!alfred!elliot (407) 290-9744
vern@zebra.UUCP (Vernon C. Hoxie) (03/22/90)
In article <3005@umbc3.UMBC.EDU>, motteler@umbc3.UMBC.EDU (Howard E. Motteler) writes: > > Does anyone know how the 3b1 power supply holds up when fed the square > wave output typical of most UPS's? I know this causes a problem for > some switching power supplies. I picked up a an UPS from a local second source outlet a couple of years ago. At that time I was working at Bell Labs so I looked up the power systems guru's. I was told by one of them that indeed the 3b1 power would work fine with a square wave input. Since then, I have been working at my computer when the lights went out but system chugged right along. No smoke. Only once since installing the cheapo square wave UPS have I found that the computer has rebooted. Apparently the outage was longer than usual and the battery had run down. When I asked the people at Telebit about connecting the Trailblazer to a square wave UPS, I got a resounding no, no, NO. Now for my question. Does anyone have any suggestions about the care and maintenance of the battery? Should it be cycled periodically? What is a convenient way to test its status? The battery is a sealed unit and as I recall, it was manufactured by a company in Castro Valley, Calif. I would have to dig it out from under the desk for any more info. vern -- Vernon C. Hoxie {ncar,nbires,boulder,isis}!scicom!zebra!vern 3975 W. 29th Ave. voice: 303-477-1780 Denver, Colo., 80212 TB+ uucp: 303-455-2670
donlash@uncle.UUCP (Donald Lashomb) (03/24/90)
In article <3005@umbc3.UMBC.EDU> motteler@umbc3.UMBC.EDU (Howard E. Motteler) writes: > >Does anyone know how the 3b1 power supply holds up when fed the square >wave output typical of most UPS's? I know this causes a problem for >some switching power supplies. I'm using a UPS with my 7300. It's a SAFE brand model 425 (425w I assume). The output is described as a "modified square wave". I've looked at the output with an o'scope - it would really scare you, all kinds of jagged peaks and valleys. BUT the 7300 doesn't seem to mind. I should also mention that, not trusting that trashy looking waveform, I've got a TrippLite IsoBar noise filter/surge suppressor between the UPS and the 7300. (8-outlet IsoBar with the 7300 plugged into the last, most filterred, outlet.) In fact I've got 2 IsoBars, one before and one after the UPS: 117vac ---> IsoBar ---> UPS ---> IsoBar ---> UnixPC This system has weathered approx 5-10 brownouts per day for 2 years with no troubles. We have alot of low-voltage problems in my area. The following is an unabashed product endorsement: TrippLite IsoBar model IB-8 noise filter/surge suppressors are great. I have a hi-freq welder on the same branch circuit as my UnixPC. The IsoBar protects the computer with no problem. May all your cycles be 117vac @ 16.666ms -Don
gwr@nz8r.UUCP (Gregory W. Ratcliff) (03/24/90)
The 3b1 supply just rectifies the line as I remember, not really
sure what the monitor need though. Your square wave ups should
work just fine, in fact the supply may like it better than AC.
If you try it out please post the results.
gwr
--
Gregory W. Ratcliff, {osu-cis}n8emr!uncle!nz8r!gwr
ham radio,aviation,tcp-ip,unix-pcs.ostroff@Oswego.EDU (Boyd Ostroff) (03/26/90)
In article <684@nz8r.UUCP> gwr@nz8r.UUCP (Gregory W. Ratcliff) writes: > >Your square wave ups should >work just fine, in fact the supply may like it better than AC. >If you try it out please post the results. > I have been using a Tripp-Lite BC-325 to power my 3B1 and 2400 baud external modem ever since last summer. We have really unreliable power here (I live in a very rural area) and experience numerous blackouts and brownouts. This UPS has worked fine with my system on a number of occasions. I got around 40 minutes of backup time in one instance. The computer is perfectly happy with the square wave power from what I can tell, though the monitor exhibits some "waviness" (wouldn't want to have to look at it *too* long like that :-). I picked up this unit after a real nasty power hit wiped out my disk and (of course) my backup procedures had been less than "ideal".... My advice to anyone who values their time (let alone their hardware) is to get some kind of UPS! I got mine for about $300 from Jameco, but I saw an ad for the same model for under $250 in this months Computer Shopper... ||| Boyd Ostroff - Tech Director - Dept of Theatre - SUNY Oswego ||| Sys Admin - "The CallBoard" - (315) 947-6414 - 1200/2400 baud ||| ostroff@oswego.oswego.edu - cboard!ostroff@oswego.oswego.edu
elliot@alfred.UUCP (Elliot Dierksen) (03/26/90)
In article <1990Mar26.053828.15880@oswego.Oswego.EDU>, ostroff@Oswego.EDU (Boyd Ostroff) writes: > In article <684@nz8r.UUCP> gwr@nz8r.UUCP (Gregory W. Ratcliff) writes: > > > >Your square wave ups should > >work just fine, in fact the supply may like it better than AC. > >If you try it out please post the results. I have an American Power Conversion 450 AT which uses modified sine wave output and has a 1 ms transfer time. I use this to keep my 3B1 & it's expansion unit up. I decided to get a UPS after the Xmas brownouts ate my 3 week old HD. Ho, Ho, Ho!! :-( I have tested this one several times and it has worked. This particular unit was reccomended to me by name by a guy at the Hotline. He used to work for a VAR that sold lots of 3B1's and he had good luck with these units. I got mine for ~ $330 out of Computer Shopper. 450 watts in case you hadn't guessed. Just for those of you that don't have reference manuals, the only comment it makes is that the power usage is supposed to <= 400 watts. You might be able to get by providing less, but it doesn't sound like a very good idea to me.... EBD -- Elliot Dierksen "I don't care if my lettuce has DDT on it, as long as it's crisp!!" -- Jorma Kaukonen Work) {att,codas}!candi!fang!ebd (407) 660-3377 Home) {peora,uunet,ucf-cs}!tarpit!alfred!elliot (407) 290-9744
levy@cbnewsc.ATT.COM (Daniel R. Levy) (03/28/90)
In article <3005@umbc3.UMBC.EDU>, motteler@umbc3.UMBC.EDU (Howard E. Motteler) writes: > > Does anyone know how the 3b1 power supply holds up when fed the square > wave output typical of most UPS's? I know this causes a problem for > some switching power supplies. The 3B1 power supply input is a voltage doubler / brute force capacitive filter circuit. The switching circuit doesn't see but a few volts of ripple. The peak to peak value of the input waveform is what matters; so long as the p-p value of the UPS output approximates that of a 120v (RMS) AC sinewave (i.e., about 320v p-p) it ought to work OK. -- Daniel R. Levy >>> God: just say "yes" <<< AT&T Bell Laboratories UNIX(R) mail: att!ttbcad!levy, att!cbnewsc!levy 5555 West Touhy Avenue Any opinions expressed in the message above are Skokie, Illinois 60077 mine, and not necessarily AT&T's.