Load
shedding and power outages. These problems have become a sort of second nature
to us Pakistanis. There used to be a time when a power breakdown of even one
hour would force the people to come out of their homes and bring those WAPDA
guys to fix the problem. But now, it’s usually a sigh of relief if there’s no
unscheduled breakdown. The scheduled one is often one hour outage after every two hours.
For those who can’t live without their computers
and internet for any or no reason, this situation is a worst nightmare. For the
unprivileged ones not having a generator/UPS to power their routers, this
solution is going to be a blessing
At least it is for me.
This is a rough, simple and NOT a sophisticated
solution by me, but works! You can not only power DSL / WIFi routers for HOURS
but also any other appliance that can work at 9V or 12V. Keep the internet
alive, and use it on your laptop or cell phone, 24×7!
I
use it to power my PTCL DSL ZXDSL 831CII DSL Router AND a TP-Link WR740N
WiFi router. PTCL router’s ratings
are: 12VDC 500mA, TP-Link’s: 9VDC 700mA.
That’s why I’ve taken two outputs.
Circuit Diagram – DIY UPS for
DSL Modem/WiFi Router:
Click to Enlarge
Parts:
o
One 12V 7AH lead acid battery.
o
One 16 or 18V laptop charger, max 2-2.5A current to charge the
battery.
o
Five 1N5404 Diodes
o
One LM338T Linear voltage regulator with a heatsink.
o
One 0.1uF ceramic capacitor
o
One 1uF electrolytic capacitor (note the polarity of capacitor)
o
Two resistors. R1 = 2.6kOhm, R2= 250 Ohms.
Things that you need to note!!:
o
Make sure you check the specs of your appliances, in this case,
router/modem first.
o
If you are only using a single router, just remove the respective
part from circuit diagram. E.G, if you are using a 12V router, you don’t need
those 4 diodes and 9V output jack.
o
You need to attach a DC Pin to the outputs of the circuit. The
same pin that is connected to your adapters, which go into your modem. Now, you
don’t need that adapter. Just buy a same pin from the market.
o
You can give input from a laptop charger of 16V to 18V. Keep in
mind the current rating of charger too, as higher current ratings can damage
the battery quite quickly. Even 2A current is too much for a battery of 7AH. It
should be around 700mA, but that will also cause slow charging.
o
You must also attach a heatsink with LM338T IC. It gets VERY HOT
during operation!
I used veroboard to build the circuit. You can
use either that (will have to solder things), or use a breadboard.
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