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Miniature Tx and KX-131 camera setup


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#1 ssassen

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Posted 28 November 2007 - 11:08 AM

With the popular Lawmate and Airwave transmitter modules that are sold by various vendors it is relatively easy to get a FPV camera setup up and running. Unfortunately these regularly use a cased KX-131 camera and a 500mW 2.4GHz transmitter, a combination which isn't exactly small, lightweight or power efficient.

For smaller planes, or those trying to save as much weight as possible, this poses a bit of challenge. However in my quest to find exactly such a solution I came across a miniature 10mW 2.4GHz Tx sold by Rangevideo (http://www.rangevideo.com). This Tx has ample power to allow for FPV flying up to about 1km away. Below you'll find a detailed description how you can use that miniature Tx to create a miniature, yet high resolution, FPV camera.

In order to save as much weight as possible it makes sense to use an uncased KX-131, which not only shaves about 10-grams off of the weight of the cased version, but also can be powered off of 5V directly, a voltage which we have available in any RC plane already. The Tx itself is also running off of 5V hence we tackled our power requirement issues in one fell swoop. Below you'll find the uncased KX-131 camera and 10mW Tx pictured. I already attached a lead with a JST plug that plugs directly into a spare channel on your receiver.

Uncased KX-131 and miniature 10mW 2.4GHz Tx

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I've opted to glue the miniature Tx to the back of the KX-131 camera directly using 5-min epoxy, but obviously it needs to be shrink wrapped prior to doing so, else we might get shorts or worse. I use the same type of shrink wrap that's used with battery packs, this is very thin, light and durable. An added benefit is that it mechnically strengthens the wires coming from the Tx and provides a surface for the glue to adhere to. Also, if you ever need to remove the miniature Tx you only have to cut the shrink wrap to gain access to it. I opted to remove the connector header on the KX-131 and solder the wires onto the PCB directly.

Miniature 10mW 2.4GHz Tx shrink wrapped and connected to KX-131

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KX-131 camera and miniature 10mW 2.4GHz Tx glued together

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Now we need to make a stable base for the KX-131 camera and the miniature Tx to be attached to. I often use L-shaped ABS plastic strip for these kind of things, as it is light, durable and can easily be drilled, milled, sanded or cut to size. I cut a length of black ABS strip to the right size, drilled an 8-mm hole in the bottom and milled a 3-mm slit in the back for the power lead to pass through. The 8-mm hole in the bottom will hold a 8-mm neodymium magnet which mates with another that's glued to the plane's fuselage. All pieces are subsequently (in steps, not all at once) glued in place using 5-min epoxy. The pictures below illustrate how it all goes together.

L-shaped ABS strip to attach camera and Tx to, front view

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L-shaped ABS strip to attach camera and Tx to, back view

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When the 5-min epoxy has cured you're left with a sturdy, yet miniature, FPV camera setup that'll take some abuse and come back for more. All that's needed now is a shrink wrap around it to protect it from the elements, ie. rain, dust, sand, bird poo and of course the inevitable landing that went awry. When that's done, all that's needed is to connect it to a free channel on the remote control receiver, turn on the video receiver and dail in the right channel and you're good to go, provided you attached the miniature FPV camera to your plane properly first of course.

The finished miniature FPV camera, looking spiffy

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Obviously this little how-to wouldn't be complete without some comments about weight, power consumption and all that other information that matters to us FPV enthusiasts. The miniature FPV camera tips the scale at just 28-grams, which should make it something of a record I guess, just don't sneeze at the field when you're holding it, it might get lost in the grass. Power consumption is a mere 190mA at 5V, which translates to almost 1W. However this does not pose a problem for the majority of ESCs with BEC, those are rated at 2A mostly, hence 190mA will not cause for an alarming raise in temperature.

Cheers,

Sander.
Cute, cuddly and colorful, beware the nasty bite

#2 twinturbostang

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Posted 28 November 2007 - 12:04 PM

Looks great! Probably similar to what Kilrah has done with his camera/Tx setups. I've thought about doing something similar with a 50mW Tx I have, which is very similar in size to the 10mW, and putting it on one of my small park flyer or 3D planes. The step by step instructions are great!

Question though... where do you get that heat shrink from? I've been wanting to get some nice lightweight stuff for this sort of thing and other projects.

BTW, will a JST physically plug into a receiver? I thought you needed a 3 pin Futaba or equivalent connector (with just +5V and ground connected of course).

#3 ssassen

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Posted 28 November 2007 - 12:13 PM

Twinturbostang,

Question though... where do you get that heat shrink from? I've been wanting to get some nice lightweight stuff for this sort of thing and other projects.


In Europe it is available from Conrad Elektronik (http://www.conrad.de) but I'm sure you'll be able to find something similar locally.

BTW, will a JST physically plug into a receiver? I thought you needed a 3 pin Futaba or equivalent connector (with just +5V and ground connected of course).


Yeah, no problem there, pin diameter is the same. You can obviously also use a normal Futaba or JR plug of course, but I had these leads handy with JSTs already crimped on.

Cheers,

Sander.
Cute, cuddly and colorful, beware the nasty bite

#4 ssassen

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Posted 30 November 2007 - 10:29 AM

Obviously I wanted to mount the miniature FPV camera to one of my planes. However my transmitter (Graupner MX-12) isn't compatible with any of the head tracking solutions available so I needed to device a solution of my own. I deviced a pan camera solution by using the gear channel (5), the rocker switch and some creative programming in the Tx menu.

Poor man's pan camera


If anybody is also using a Graupner MX-12 I'd be happy to explain how to set up the Tx to enable this simple pan camera to work with just a single servo and the rocker switch.

Cheers,

Sander.
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#5 saabguyspg

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Posted 04 December 2007 - 12:11 PM

Hi there, I am also using an uncompatable radio (dx7) and have been digging into my flaps, aux, and gear to try and pan / tilt.

I have for now used rudder and flaps and it works... I would love to hear how you did it.

Thanks!!!

#6 ssassen

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Posted 04 December 2007 - 12:51 PM

Saabguyspg,

I'd be happy to assist, but that question is kinda hard to answer, that would be like you trying to answer a BMW guy's question on how to change his car's airfilter, obviously you know your Saab initimately, but not someone else's BMW, right? :D

Having said that it is obvious that my Graupner MX-12 bears no relevance to your DX-7. But it might have a similar feature. Most TXs have the option to retract and extend gear, on a set channel, which is what I used in combination with a toggle switch to define three positions on that channel, 100%, 0% and -100%.

Cheers,

Sander.
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#7 saabguyspg

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Posted 04 December 2007 - 03:26 PM

True that, but fortunately for us... an airfilter is an airfilter in this case.... haahh..

So you are doing similar to me where I use my flaps three position switch, where it is 5 0 and -5 volts. For my tilt

I was hoping you had some crazy way to turn the gear channel into a proportional one. I'll have to check out your video when I get home.

Nice I just noticed you are in Purmerend Netherlands... I have lots of family there... I was just there about a year ago... love it!!!

Edited by saabguyspg, 04 December 2007 - 03:27 PM.


#8 ssassen

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Posted 04 December 2007 - 03:38 PM

Nice I just noticed you are in Purmerend Netherlands... I have lots of family there... I was just there about a year ago... love it!!!


No! Really? And you drive a Saab as well? Are you Dutch by any chance? This is too much of a coincidence :D

Cheers,

Sander.
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#9 saabguyspg

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Posted 04 December 2007 - 03:41 PM

lol... yes, 50% dutch but I do not speak it sorry... :unsure:

I will pm you............

ps if only they made a 900mz transmitter that small... I would be allll over it!

Edited by saabguyspg, 04 December 2007 - 04:28 PM.


#10 emowillcox

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Posted 21 September 2008 - 10:01 AM

I just got my KX131 and I am taking the case off to save weight but can't figure out how to connect the lens once I remove the case?
Got any ideas?

thanks< MIKE

#11 Kilrah

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Posted 21 September 2008 - 10:23 AM

I'm afraid you'll have to make yourself some sort of lens holder... the uncased KX131 has a different circuit board and a custom lens holder.

#12 eander315

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Posted 30 October 2008 - 07:58 PM

ps if only they made a 900mz transmitter that small... I would be allll over it!


There are a few options available in 900MHz, all look exactly like that the TX above. You can buy one at Super Circuits:

http://www.supercirc...ers/AVX900MICRO

They have 2 or 3 different models. I haven't seen anyone try one of these yet, not sure how well they work. They look very interesting for use in small foamies or helis.