A 2 second UPS?

tsk1979 · 16th June 2008, 18:58

Our apartment building has generator backup.
So when power goes, the PC modems shuts down, and then after a couple of minutes generator starts, and the modem switches on and connects.
So far so good.
The problem is when power comes back.
they do a changeover during which the voltage drops for half a second before coming back. This hangs the modem.
Now if power went and came back, it wouldn't matter, but modem hanging means I have to turn it off and on,
Is there a cheap DIY way of making myself a UPS which gives around 2 second backup.
Easily availability of parts for this DIY is important.

If I put a cheap 10 mF capacitor in series, will it do? I am gravitating towards the capacitor solution. I will connect the DC output of the adaptor to capacitor, so it will charge. Then when power dips it will cushion against the inverted spike.

merve_extreme · 16th June 2008, 19:03

I assume you are talking about the Dlink Modem,It uses an AC-AC adapter and resets even on UPS switchover.

tsk1979 · 16th June 2008, 19:16

Nope, its not dlink and it has AC-DC adaptor. Its a Beetel ADSL modem

condor · 16th June 2008, 19:24

Suggest pick up a small capacity UPS - will be a clean install & use.

tsk1979 · 16th June 2008, 19:32

Can I get a 200W UPS somewhere?
I would like to power my laptop and modem with that.

low_bass_makker · 16th June 2008, 19:33

A cap will be a cheap and good try. But put a bigger value. It will restore some energy when there is a dip. Atlest 1000-2000 mF.

anupmathur · 16th June 2008, 19:34

Wouldn't 10 mF be too little? What's the DC supply for the modem? What's the mA rating on the adapter?

greenhorn · 16th June 2008, 20:08

isnt the cap supposed to be in parallel?

anupmathur · 16th June 2008, 20:16

Quote:

Originally Posted by greenhorn

isnt the cap supposed to be in parallel?

Of course you're right!

Everybody seems to have missed the fact that tsk has written 'series'!

low_bass_makker · 16th June 2008, 21:09

I think he is using as a filter but DC will not pass.

anupmathur · 16th June 2008, 21:12

Quote:

Originally Posted by low_bass_makker

I think he is using as a filter but DC will not pass.

As a filter for what?

He's clearly said he wants to 'augment' the DC storage!

low_bass_makker · 17th June 2008, 00:03

Quote:

Originally Posted by anupmathur

As a filter for what?

He's clearly said he wants to 'augment' the DC storage!

To clean the spikes in the DC out put of the ac-dc converter

phamilyman · 17th June 2008, 00:07

boss,

dekho before you try a cap soln, please visit nehru place. you will get junta selling old UPSes for 250-400 bucks (seen it meself).

These ones are typically with a gone case battery that only last a few seconds.
but from what you say - few >> 2.

QED

Vid6639 · 17th June 2008, 00:18

Quote:

Originally Posted by low_bass_makker

Atlest 1000-2000 mF.

L_B_M paaji, 1000mf? or uF? 1000mF = 1F which is a huge cap value.

If you can spend like 1000 odd bucks you should get a wipro or a proview one.

DerAlte · 17th June 2008, 00:53

I had the same problem years back with a Sony cordless phone! I had used a 10000uF capacitor, but even that was not a fool-proof solution.

It is better that you use a small UPS, especially like what @phamilyman described. The electronics part of the UPS doesn't cost much, the battery is the killer - you can get a new UPS for the retail cost of a battery.

I have a 1992 vintage 0.5KVA UPS that powers my modem & LAN switch at home - had replaced the batteries a while back. Must check the backup time with the current load some time.

16th June 2008, 18:58	#1
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,725 Thanked: 23,053 Times View My Garage	A 2 second UPS? Our apartment building has generator backup. So when power goes, the PC modems shuts down, and then after a couple of minutes generator starts, and the modem switches on and connects. So far so good. The problem is when power comes back. they do a changeover during which the voltage drops for half a second before coming back. This hangs the modem. Now if power went and came back, it wouldn't matter, but modem hanging means I have to turn it off and on, Is there a cheap DIY way of making myself a UPS which gives around 2 second backup. Easily availability of parts for this DIY is important. If I put a cheap 10 mF capacitor in series, will it do? I am gravitating towards the capacitor solution. I will connect the DC output of the adaptor to capacitor, so it will charge. Then when power dips it will cushion against the inverted spike. Last edited by tsk1979 : 16th June 2008 at 19:00.
	() Thanks

16th June 2008, 19:03	#2
merve_extreme Senior - BHPian Join Date: Apr 2004 Location: Mumbai Posts: 1,359 Thanked: 18 Times View My Garage	I assume you are talking about the Dlink Modem,It uses an AC-AC adapter and resets even on UPS switchover.
	() Thanks

16th June 2008, 19:16	#3
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,725 Thanked: 23,053 Times View My Garage	Nope, its not dlink and it has AC-DC adaptor. Its a Beetel ADSL modem
	() Thanks

16th June 2008, 19:24	#4
condor Distinguished - BHPian Join Date: Jun 2006 Location: Speed-brkr City Posts: 16,051 Thanked: 16,387 Times View My Garage	Suggest pick up a small capacity UPS - will be a clean install & use.
	() Thanks

16th June 2008, 19:32	#5
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,725 Thanked: 23,053 Times View My Garage	Can I get a 200W UPS somewhere? I would like to power my laptop and modem with that.
	() Thanks

16th June 2008, 19:33	#6
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,815 Thanked: 305 Times View My Garage	A cap will be a cheap and good try. But put a bigger value. It will restore some energy when there is a dip. Atlest 1000-2000 mF.
	() Thanks

16th June 2008, 19:34	#7
anupmathur Senior - BHPian Join Date: Sep 2007 Location: New Delhi Posts: 3,095 Thanked: 311 Times	Wouldn't 10 mF be too little? What's the DC supply for the modem? What's the mA rating on the adapter?
	() Thanks

16th June 2008, 20:08	#8
greenhorn Senior - BHPian Join Date: Apr 2007 Location: KL-01 Posts: 7,845 Thanked: 4,756 Times View My Garage	isnt the cap supposed to be in parallel?
	() Thanks

16th June 2008, 21:09	#10
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,815 Thanked: 305 Times View My Garage	I think he is using as a filter but DC will not pass.
	() Thanks

17th June 2008, 00:07	#13
phamilyman Senior - BHPian Join Date: Jul 2007 Location: Gurgaon Posts: 5,974 Thanked: 4,663 Times	boss, dekho before you try a cap soln, please visit nehru place. you will get junta selling old UPSes for 250-400 bucks (seen it meself). These ones are typically with a gone case battery that only last a few seconds. but from what you say - few >> 2. QED
	() Thanks

17th June 2008, 00:53	#15
DerAlte Senior - BHPian Join Date: Mar 2007 Location: Bangalore Posts: 8,069 Thanked: 2,919 Times	I had the same problem years back with a Sony cordless phone! I had used a 10000uF capacitor, but even that was not a fool-proof solution. It is better that you use a small UPS, especially like what @phamilyman described. The electronics part of the UPS doesn't cost much, the battery is the killer - you can get a new UPS for the retail cost of a battery. I have a 1992 vintage 0.5KVA UPS that powers my modem & LAN switch at home - had replaced the batteries a while back. Must check the backup time with the current load some time.
	() Thanks