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Thursday, October 7, 2010

Solar Powered DIY Portable HotSpot | VoltsXamps

Solar Powered DIY Portable HotSpot

Ever wondered what it would be like to have your own hotspot no matter where you went? Well now you can with this portable solar powered Wi-Fi repeater.

This little mod is simply a wifi router connected to 5 AA batteries that is charged with the built in solar panel and all mounted into a little cigar box. I used this in the back window of my car and no matter where I am at I am able to surf the net and check email within 150 feet of my car.

Here is how it works:

First there is the solar panel. This panel puts out enough voltage and current to run the wireless router without the batteries. The batteries are simply there to act as a flywheel in case of clouds, shade, etc. The panel then recharges the 5 AA batteries which in turn supply the energy needed to run the router.

The router runs a custom firmware called dd-wrt that automatically scans for open hotspots and then connects to the strongest signal it finds automatically. It then repeats the signal locally so you can surf the net with a more reliable connection. No need to search for open hotspots, it finds em and connects to the strongest for you.

This comes in handy as one is at work and their car sits in the parking lot all day long. Then when I come out for lunch I am able to immediately login to my asus netbook and check email, etc.

Notes; This router (Linksys WRT54G v8) will run on up to 12 volts 1 amp or 12 volts 500ma or 6 volts 500ma. I know because I personally tested it with other wall warts of these voltages and amperages.

The solar panel puts out 7.5 volts @ 500 ma in direct sunlight. So no charging circuit was needed as the panel is unable to over charge the batteries due to the fact that the batteries voltage is too close to what the panel puts out in regards to voltage. Now you might be asking how can this router take such different voltages and amperages as stated…? Well, the router has a built in voltage regulator that takes care of any voltage ranging from 6v DC all the way up to 24 volts DC.

In further testing it did not seem to effect the unit in anyway if it was using 12 volts @ 1,000ma or 6 volts @500ma.

One might prefer to use the 12 volts 500ma instead simply due to the fact that a charge regulator is alot easier and cheaper to get for 12 volts then it is for 6 volts. The one below is one that I have that was less then $20 on ebay so I could use it for a larger 12 volt battery if I wanted to.

Obviously the larger the amp hour batteries that are used the longer it will run without sunlight however it will also take longer to charge batteries. You would need to find the balance for how long you want the unit to run for. For example, if you simply want it to repeat signals during the day then you would not need a large battery bank but solely for the purpose as to act as a “flywheel” for when clouds pass over.

Here are some pics of the unit I took.

Above; Here is the router mounted into the cigar box. You can also see the 5 AA battery holder there however it could also run on 10 AA batteries (12 volts) However the panel I had would charge 6 volts perfect but did not provide enough voltage to charge  a 12 volt battery bank so I used 6 volts instead.

Better view of the battery holder. You can also see the antenna sticking out the top of the box. It would probably be even better to attach a higher gain antenna but this was all I had at the time.

A top/back view of the box. Its a cigar box made of wood.

Side view of the box showing the antenna sticking out. The antenna can rotate to so it can be adjusted depending on if you have the box sitting up or down as seen in the photo.

View of the toggle (on-off) switch. This really did not need an on/off switch but I had one on hand so I used it. You may also notice the orignal AC adapter plug in the top left hand side of this photo. It can still be plugged into the wall wart if you choose to use the grid.

Another view of the unit.

The router is literally jammed into the box so tight that there was no need to glue or secure it in any way. I literally had to push with alot of force to get the board to go into the box between the sides.

This was a fun project and it works very well however to do things right there should be heat shrink tubing used over the wires where they connect and not electrical tape. I did however take the time to actually solder the connections;-)

I hope you all have fun with this project as it will be very useful to you no matter where you happen to roam.

If you want me to custom build on of these units for you please contact me. I do not do this for a living however I also understand that there are people out there that either do not have the time, patience to put together a project like this.

Thanks for viewing. Leave me comments.


Portable WIFI solar hotspot

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