please help about circut

[ikramgondal]

Dear friends. ... I want to use 3 different types of internet devices which oprates on 9V 0.6A and other tow on 12V 1A (labeled on its adopters)... my question is that what I can oprate on battery of UPS which 12V and I don't know about amp output. If yes then tell me complete circuit. ... I will wait for your helpfull replys.
Thanks in advance.
M.IKRAM

[pebe]

It's quite simple. Wire the two 12V internet devices directly across the 12V battery.
For the 9V device, use a 'buck' voltage dropper like this one:

http://www.ebay.co.uk/itm/1-25V-37V-1pc ... 232f485e04

Connect its input terminals to the 12V battery. Use a multimeter to set the voltage across the output terminals(with the adjustable pot) to 9V. Then connect the 9V internet device to its output.

[ikramgondal]

Respected Dear I am very thankful to you...
I understand fully but I have one more question because I have confusion about this, what the amp per hours of battery is not related to oprating mA of device? ?? Mean to say in this circuit I just see volts and please briefly explain tabout he amp per hours , operating device voltages and between relationship. ..
I will wait for your good reply... thanks

[pebe]

Any device will only take the current that it needs. In your case, the two 12V devices will take 1A each. The 9V 0.6A device when connected to a buck converter fed from a 12V supply, will take about 0.45A. So the total current taken by all three devices will be 2.45A.

Any lead acid 12V battery (whether for UPS or anything else) will have an 'Ah' rating. That shows its capacity to store electricity, and is the product of how many Amps it can supply for a given number of hours. For example a typical UPS battery has a rating of 17Ah. That means it can supply 1A for 17hours, or 2A for 8.5hours, or 17A for 1hour, or any combination of amps and hours that equals 17.

In your case the current required is 2.45A, so a 17Ah battery could supply that current for 17/2.45 = 6.93hours before it became discharged.

I hope that helps.

[ikramgondal]

Ok I fully understand. ... thanks.... mean if I connect device which use 34A then I can use this 17A/h battery for half hour backup.
Now tell me other thing that after googling I calculate the resistance (5ohm and 1.8 waat ) which I use to reduce 12v to 9v for this 0.6A device by use ohm law (V=I.R and P=I^2.R).... can I use or not?.... I am in village and here not avail electronic components so plese tell me easiest thing like this resistance method. ...

[pebe]

A 5ohm 2W resistor would be OK, but check with a multimeter that you actually have 9V supplied to the device.

I am surprised you cannot get components. Can you not order parts from Ebay and get them delivered?

[ikramgondal]

Ok I will check and here I am not any facility to buy online

[pebe]

That's surprising. Can't you get postal packet deliveries? Which country do you live in?

[ikramgondal]

Oooh.... I have not account which I can use to order.... and I live ower sweet country ♥♡PAKISTAN♡♥

[pebe]

If you have a bank account then you can order from Ebay and pay with Paypal. They will then debit your bank account for that amount. They make no extra charges for doing that and they give a free guarantee that an Ebay seller cannot swindle you.

[ikramgondal]

I have bank account but PayPal not spotted Pakistan

[pebe]

It's a bit off topic, so I'll continue by PM.