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Portable Wifi Extender for Drone... help!

Discussion in 'Radio and Wireless' started by Jim_Lad, Jan 18, 2017.

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  1. Jim_Lad

    Jim_Lad

    4
    2
    Jan 18, 2017
    Hi,

    Wondering if someone here more knowledgeable on this stuff than I am (and it wouldn't take much) can help me. I’ve tried to look on various forums/videos of people who have done similar but can’t find an exact answer.

    I’m looking to use a wifi extender to enable me to fly my AR Drone 2.0 further than I can currently get with my iPhone wifi which is around 15-20m. As it’s for this use it only has to power the extender for around 30mins – 1hr (but I don't want to risk it dieing earlier than that and downing my drone).

    I’ve seen people who have made their wifi extender portable using a Lipo battery cell but from what I can see these have a higher voltage than the wifi extender I have allows.

    I currently have the following:
    Wifi Extender: TP-Link TL-WA801ND, states Power: 9v, 0.85A.

    Parrot AR Drone 2.0 Battery: 1500mAh Lithium Polymer Battery
    https://www.amazon.co.uk/Parrot-AR-Drone-1500mAh-Lithium-Polymer/dp/B00DAL5GD2

    This is probably a stupid question but what stops me buying a normal 9v battery, PP3 connector and terminating into a 2.5mm DC power connector and powering the extender with that? This looks like a cheap option but I presume the battery life would be poor, I’m not sure if it’s even possible or how long it would last?

    I guess if this isn’t an option the next thing is to buy a 2.5mm DC power connector (http://www.maplin.co.uk/p/maplin-25mm-screw-terminal-dc-power-plug-n82kt), wire it to a mini-Tamiyaconnector (http://www.maplin.co.uk/p/race-pack...BG7IsgA7rhh8NRI9kf9Wm2YVU1jbP3aF92RoC1J3w_wcB) and connect it to a large lipo battery. However I’m not sure what type of battery of this type would be suitable for the wifi extender? The one’s I can find are a higher voltage than the extender states are required.

    Ideally the answer wouldn't require too much electrical skill in manufacturing!

    If anyone could help clarify what would work best and how to do it, it would be greatly appreciated, usually try and figure these things out myself but I’m stuck on this one and a little bit of electrical knowledge is a dangerous thing!

    Thanks in advance for your help!

    Jim lad
     
  2. Lightning

    Lightning

    45
    4
    Oct 12, 2013
    Story of my life, rubbish WiFi range for flying.

    I've never though of using a WiFi extender though I might give that a go, thanks :p

    I would say there is nothing stopping you from connecting a 9v but I have my doubts you could pull 0.85Amps from a single battery and it would probably not last that long as you said.

    http://www.techlib.com/reference/batteries.html
    found this on google... looks like with a 0.85A draw and 500mAh it would last around 35 minutes in theory.
    I'm not sure what the C rating of normal 9v is but I doubt it would be able to supply this comfortably... my gut says no.
    Perhaps put a few in parallel to spread the current draw?

    If you are going for the Li-Po approach, I can't remember if I have seen any 9v Li-Po but if you can get one then it should work better, if you can find the right connections for it. LiPos have a much better capacity for drawing current so without checking I would say that is a good solution. :)

    If you cannot find a 9v LiPo then a simple '9v voltage regulator circuit' might be within your capabilities to build, or you maybe able to buy one? For example with a 11.1v Li-Po input regulated down to 9v and then connected to the extender with the connectors you stated.

    Hope this helps ^_^
     
    Robert Brown likes this.
  3. Jim_Lad

    Jim_Lad

    4
    2
    Jan 18, 2017
    Hi Lightning,

    Thanks for the response, much appreciated.

    Yes, there's a few videos on YouTube of successful wi-fi extended flights, some taking them a lot further, I just wish they showed you detail on how they powered them!

    You've confirmed some of my thoughts regarding the use of the 9v battery. I think, as you've said, it'll be best to go down the Li-po route.

    Do you (or anyone else) have any more information on how to make the '9v voltage regulator circuit'? Again I've tried to look into it but can't work out what diodes I would need... if they're even part of the circuit!? As it's going beyond my knowledge I'm probably not searching for the right thing...

    Is this the link below the kind of thing I could buy? Though it say's the output current is 5A, if the wifi extender states 0.85A does this mean it would be too much for it?

    http://www.newfrog.com/p/12v-24v-st...currency=GBP&gclid=CJyq7ofB1NECFRITGwodttkDqw

    Thanks again for your help.

    Jim
     
  4. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I'm curious what the TP-Link can *run* at... You may be able to bend the 9V requirement a little, or a lot depending on how it's designed.
    In any case, there are two incredibly easy, but potentially wasteful solutions for you:
    - Use a 3S battery, but connect it to the TP-Link through 3 Diodes. The diodes will drop ~2.1 volts, leaving the remainder for the TP-Link. (Approx 9V with a 3S Li-Po battery)
    - Use a linear regulator "LM7809", It's capable of putting out 1A and requires simply an Input+, Negative, and Output+.
    These two solutions work, are easy, but waste energy as heat. Considering you only have a small window, this should be more than acceptable. Both solutions may result in warm/hot components! Use a heat-sink on the LM7809, and use diodes rated to handle at least 1A.

    The more efficient solution would be to buy a 'switch-mode' 9V regulator. Most likely a 'Buck' type to lower the voltage down to 9V. You could also use a 'Boost' type to bring the voltage *up* to 9V. These are more effecient but more complicated to build. Luckily you can find them online for very cheap prices in fixed and adjustable models.
    (Get an adjustable model and you can re-use it for other projects)
     
    Jim_Lad likes this.
  5. Lightning

    Lightning

    45
    4
    Oct 12, 2013
    Hi Jim,

    I had a look over the weekend at WiFi extenders, you might also get a lot more range with a directive antenna and an extender that supports it, I have seen some cheap 2.4 GHz Yagi antennas that go kilometers. :D

    As Gyrd3 said, the LM7809 was what I had in mind as well, it saves you a lot of design work with transistors/diodes and you only need to connect-up 3 pins and a heat sink.

    As for the link you sent, that product would do the job if you choose to use it. The current it states on the product spec is just the maximum it can provide, your extender only needs 0.85A so this is the most you would see drawn from the supply.

    I've also seen some "LM7809 voltage regulator" boards that you can buy pre-made on eBay that would save you the hassle of building anything (around £3-£4) if you are looking for alternatives.

    You will have to post your results if you get this working well ^_^
     
    Jim_Lad and Gryd3 like this.
  6. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I thought about this as well... but figured keeping a drone inside the cone of a directional antenna would be a bit of a pain unless you go out with a spotter.
    Although... taking a friend and getting them to help 'gun down' your drone with a directional antenna sounds like a better idea than throwing money and power at a WiFi Extender... as they are simply 'repeaters' that hopefully have better Rx and Tx than your craft and Phone.
    If the Rx is not good enough, you'll still be limited on distance based on the drone's Tx power
     
  7. Jim_Lad

    Jim_Lad

    4
    2
    Jan 18, 2017
    Lightning/Gryd3,

    Great alternative solutions, gives me plenty to look into! I think I'll try to achieve 100-200m before sending it km away, don't trust my piloting skills that much just yet! Also trying to keep it relatively small to carry around.

    FYI, some people have used the wi-fi extender with an external antenna on the drone to improve the signal from it but this isn't that cheap and I'm hoping the extender alone can do the job.

    Thanks Lightning for confirming my suggestion, I've had a look for the LM7809 boards you and Gryd3 mentioned and also look like a good option.

    I'll have a think about what to do and buy some items, hopefully by then the weather will be decent enough to actually take the drone out and test it.

    I'll report back once I've tried it, I think the results will be one of the following:

    1. Lost it.
    2. Crashed it.
    3. Wi-fi extender exploded resulting in 1 and or 2.
    4. Success.

    Fingers crossed for 4!

    Thanks again for your comments, first time using one of these threads and definitely appreciate the informative replies and suggestions, great to learn a few things.

    Jim
     
    Lightning and Gryd3 like this.
  8. Jim_Lad

    Jim_Lad

    4
    2
    Jan 18, 2017
    Hi,

    So it's been a while since I raised the original question but figured I'd provide an update to give back to the website as others helped out with responses and also thought might be useful for other people in the future who might be searching for more information as I was.

    So the result was 4 with a bit of 2! So in short the home made wi-fi extender worked. However I didn't end up having to go down the voltage change route (but thanks for your help anyway!).

    I haven't pushed it to it's maximum yet and (too busy trying not to crash to check out the signal strength and what the maximum distance is!), but as mentioned before I was managing to get around 15m with standard flights just using the iPhone wi-fi, and this usually cut out unexpectedly. With the new extender I've had up to 35/40m no problems (except for then dropping to the ground as you can see on one of the height graphs! - though I think this was because I also had an additional camera attached to the drone (not something it's really designed to lift) which it struggled with (though also this was just after accidentally performing a flip with it on which I don't think was a good idea!).

    Information on the set up below, thanks to the people at the links who helped with documenting their own set up.

    Tutorial for making extender:

    Tutorial for linking AR.Drone 2.0 to extender:

    Pre-made cable: Mini-Tamiya Male RC Lead from http://www.ebay.co.uk/itm/2-3-Pin-W...d-Connectors-Silicone-Wire-Lead-/122179786478

    Plug: http://www.maplin.co.uk/p/25-x-55mm-solderless-plug-n53gu

    Extender: I obtained the extender from elsewhere but it's a TP-Link TL-WA801ND

    The plug is a few mm too long for the socket in my extender but still works, just is a bit loose (obviously not something you want to fall out mid-flight, but seems to hold okay.

    All pretty easy for an amateur like me to assemble together. With the price of the extender all in all it's around £40 to make (excluding the battery), not a bad option for extending the range - though I accept no responsibilities for the success of other peoples endeavors!

    Hope this helps anyone and thanks again to those who helped with advice.

    Good luck!

    James

    Before Extender Flight:
    Before Extender.jpg

    Extender Set Up:
    Equipment Set Up.JPG

    After Extender Flight:
    After Extender 1.jpg

    After Extender Flight (and crash):
    After Extender 2.jpg
     
  9. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Excellent! Good to hear you have made progress, and I'm glad the internal voltage regulator handles your battery just fine.
    Next step for you to increase range would be to swap out the antenna for something directional ;)
     
  10. Lightning

    Lightning

    45
    4
    Oct 12, 2013
    Wow, that's fantastic, and surprisingly simple!

    I like your use of a spare AR battery, I am using the same model for one of my ground based robots and it works really well. Those tutorials are rather useful, I may use them at a later date, some of the ranges in the video are really impressive!

    Much like Gryd3 said, I can only imagine the ranges you can get with a more directional antenna in a solid ground station setup. Change the stock 4dBi to one of the 24dBi directional Yagi antennas I have seen online and you could improve it further still, I am excited to try this myself!

    I'm impressed with that telemetry data as well, I've only got a cheap £30 WiFi FPV android quad that doesn't quite give me the same functionality :p ...Still it would be interesting to see if I could do the same sort of thing and set the standard of what you can do on a budget.

    Excellent build anyway, thanks for sharing that!
     
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