need to build a UPS for computer - Page 2 - Electronic Circuits Projects Diagrams Free

rjvh · 8th March 2008, 09:55 AM

Quote:

Originally Posted by I²R

Well, that's what a UPS is. I just bought a brand new APC 1300 kVA UPS for about $150

tested and guaranteed, why making one???

blueroomelectronics · 8th March 2008, 02:44 PM

The mains power in Karachi is very unreliable the power companies turn it off because of late bill payments or outright theft, a UPS is designed for rare power failures and will draw more power as it recharges between losses. Why not buy a generator instead?
http://www.dailytimes.com.pk/default...7-3-2008_pg5_7
http://news.bbc.co.uk/1/hi/world/south_asia/7280933.stm

hackableFM · 12th March 2008, 11:34 PM

I agree with the comments above, It will be cheaper by far to buy one than make one!

If you insist on making one then the easiest way would be to buy your inverter and run it on battery constantly, but build a charger for the batteries which can supply more current than the inverter can use. This type of UPS has absolutely no dropout what switching over to battery.

I think they call this an 'Online' UPS. If you build an inverter that switches over to battery when the mains fails then they call these 'Offline' UPS's.

I personally have a UPS pretecting my machine but I was VERY lucky in that I picked it up from a local junk stall for £1. Yes you see correctly £1.00 Fair enough this one needed a new set of batteries but they only cost £20. Maybe you should keep looking around on junk stalls, You never know what you might pick up!

hackableFM.

HS3 · 7th April 2008, 03:24 AM

My desktop and CRT, although they are rated much higher, actually only consume somewhat less than 200W. I have a 500 W UPS which came with a tiny 7AH battery which was just enough time to save your work when the power failed. When that battery failed, instead of replacing it with a similar one I got an old car battery. A battery which is unable to crank a car, specially a diesel, will still have plenty of life in it, has much more capacity than 7 Ah and it is FREE! Still, I do not expect to be able to work for hours, only that it may solve short blackouts or give me time to save my work.

If you want to maximize time off grid at the lowest price I would (1) get a laptop with a 12 V adapter and (2) install a bank of old car batteries. You can't beat that combination.

HS3 · 7th April 2008, 03:32 AM

Quote:

Originally Posted by Papabravo

A bouncing relay would never be fast enough.

My Ellipse 500 has a relay as do many others. The charge in the computer's PSU capacitors is enough to carry through the time it takes the relay to switch and the inverter to start up.

By the way, I also used to post at that other board but I left in disgust.

mashersmasher · 10th April 2008, 01:20 PM

it might work out if you can scrounge the bits from crap. maybe an old car battery being charged by a pc power supply and an old inverter could do the trick

Super_voip · 10th April 2008, 06:53 PM

I don't know what sort of PC HS3 has but I have recently been measuring PC wattages and have found that my old PC 1.4GHz with 19"CRT uses 150W,
newer quad core 2.4GHz with two LCD screens used 45W, with a decreasing power consumpution for newer PCs. The start up watts would be higher these are just the steady operating watts averaged over a week, no power saving turned on, even the screens were left on.
A UPS shouldn't be involved in rebooting a PC, that is why you get a UPS, so if the power does fail then I would need a UPS to provide 150W until I started the genset.

8th March 2008, 02:44 PM	#17 (permalink)
blueroomelectronics Experienced Member Join Date: Jan 2007 Location: Toronto, Canada Posts: 4,121	The mains power in Karachi is very unreliable the power companies turn it off because of late bill payments or outright theft, a UPS is designed for rare power failures and will draw more power as it recharges between losses. Why not buy a generator instead? http://www.dailytimes.com.pk/default...7-3-2008_pg5_7 http://news.bbc.co.uk/1/hi/world/south_asia/7280933.stm __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

12th March 2008, 11:34 PM	#18 (permalink)
hackableFM Experienced Member Join Date: Mar 2007 Location: Sitting at the computer Posts: 55	I agree with the comments above, It will be cheaper by far to buy one than make one! If you insist on making one then the easiest way would be to buy your inverter and run it on battery constantly, but build a charger for the batteries which can supply more current than the inverter can use. This type of UPS has absolutely no dropout what switching over to battery. I think they call this an 'Online' UPS. If you build an inverter that switches over to battery when the mains fails then they call these 'Offline' UPS's. I personally have a UPS pretecting my machine but I was VERY lucky in that I picked it up from a local junk stall for £1. Yes you see correctly £1.00 Fair enough this one needed a new set of batteries but they only cost £20. Maybe you should keep looking around on junk stalls, You never know what you might pick up! hackableFM. __________________ When God was handing out the brains, I thought he said trains, so I asked for a small, slow one!

7th April 2008, 03:24 AM	#19 (permalink)
HS3 Experienced Member Join Date: Apr 2008 Posts: 41	My desktop and CRT, although they are rated much higher, actually only consume somewhat less than 200W. I have a 500 W UPS which came with a tiny 7AH battery which was just enough time to save your work when the power failed. When that battery failed, instead of replacing it with a similar one I got an old car battery. A battery which is unable to crank a car, specially a diesel, will still have plenty of life in it, has much more capacity than 7 Ah and it is FREE! Still, I do not expect to be able to work for hours, only that it may solve short blackouts or give me time to save my work. If you want to maximize time off grid at the lowest price I would (1) get a laptop with a 12 V adapter and (2) install a bank of old car batteries. You can't beat that combination. Last edited by HS3; 7th April 2008 at 03:33 AM.

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10th April 2008, 01:20 PM	#21 (permalink)
mashersmasher Experienced Member Join Date: Apr 2008 Posts: 54	it might work out if you can scrounge the bits from crap. maybe an old car battery being charged by a pc power supply and an old inverter could do the trick

10th April 2008, 06:53 PM	#22 (permalink)
Super_voip Experienced Member Join Date: Jul 2007 Location: Brisbane, Australia Posts: 300	I don't know what sort of PC HS3 has but I have recently been measuring PC wattages and have found that my old PC 1.4GHz with 19"CRT uses 150W, newer quad core 2.4GHz with two LCD screens used 45W, with a decreasing power consumpution for newer PCs. The start up watts would be higher these are just the steady operating watts averaged over a week, no power saving turned on, even the screens were left on. A UPS shouldn't be involved in rebooting a PC, that is why you get a UPS, so if the power does fail then I would need a UPS to provide 150W until I started the genset.