127 replies to this topic

[Terry]

I had the same thoughts but swapped to a dummy load so the RF should be very low, also the readings are solid. Something is wrong with the TX but the fact that the 5v is good makes me wonder what, I will have to find some spare time from somewhere, dose anyone know where I can get some spare time?

Terry

[Mr.RC-Cam]

Spare time -- what's that?

What is the current draw on your other 5.8GHz 500mW Tx?

[Terry]

Hmmm just gone full circle, put a different amp meter on and the readings are ok so back to square one. I will try a flight with a 3s pack and see what happens.

Terry

[Mr.RC-Cam]

That is good to hear. Do the weird high currents return when the other meter is used again?

What is the current draw of the camera? {I'm still concerned about the load it is adding to the Tx's internal DC-DC supply.}
Does the DC-DC supply work all the way down to a 6.0V input voltage? {Need to confirm it is working correctly}

I still think that there there is a problem elsewhere. This power supply stuff was just a temporary detour before the actual troubleshooting. So there is a chance you will see the same loss of video problem again.

[Terry]

Do the weird high currents return when the other meter is used again?

Yes they do, I think it maybe the switcher confusing my Fluke.

What is the current draw of the camera

150mA

Does the DC-DC supply work all the way down to a 6.0V input voltage?

yes, at 6v it give 4.99v and at 5.5v it gave 4.77v

I still think that there there is a problem elsewhere. This power supply stuff was just a temporary detour before the actual troubleshooting. So there is a chance you will see the same loss of video problem again.

me too, what is the chance of the switcher overheating and shutting down?

Terry

Edited by Terry, 07 July 2010 - 12:50 PM.

[Mr.RC-Cam]

... what is the chance of the switcher overheating and shutting down?

With the unexpected 150mA drawn by the 5V camera, this is possible. Especially on a 2S. Regardless of 2S/3S, there is definitely zero room for error in this situation.

After you have checked everything else (still could be a solder connection or other evilness), I suppose a test flight with a healthy 3S pack is in order. Bring a spotter!

[docphi]

Just a quick update - The plane slipped from my hand during launch (Darn this girly arm!) and splashed down in a huge puddle of water. I've let all the components dry out for several days and tested them on the bench. All looks fine. Back in the plane and we'll try again!

[Devonian]

All my testing has come to a halt - I have a problem with my left eye as it is all 'blurry' and I can't focus properly and don't trust myself with flying.
Even soldering a servo lead is difficult enough at the moment.

Here are a couple of clips from my homebrewed 5.8 rig - works well.

'First light'
http://www.vimeo.com/12693548


Made and fitted an LC filter for the supply line to the Rx
http://www.vimeo.com/12708308


The rig I got from Thomas in a little r/c car...
http://www.vimeo.com/12891188

I'll do some more as soon as my eye is better.

Nigel.

PS - how do you embed a video link (so it appears in a box as opposed to a hyperlink)??

[Mr.RC-Cam]

Made and fitted an LC filter for the supply line to the Rx

As you experienced, R/C switch-mode BEC's often have a lot of ripple, even those advertised as low noise. Sometimes the required LC filtering can be a burden. But it looks like you solved yours.

how do you embed a video link (so it appears in a box as opposed to a hyperlink)??

Normally you would click the Insert Media Icon, then enter the URL. But for some reason it is not working with Vimeo media (YouTube works fine).

Edited by Mr.RC-Cam, 11 July 2010 - 08:30 AM.
Fixed typos.

[Terry]

Just had a quick test flight, no spotter availible as usual so I turned round at 8000ft out and 55% on the meter. No sign of the cutting out problem so looks like 3s has done the trick although it is a bit cooler today too.

Terry

[Mr.RC-Cam]

No sign of the cutting out problem

That sounds very promising. Thanks for the report.

[Cyb]

Hi,

I am interested in this package! Would it be possible to provide an antenna for the simple Rx with SMA ?
Do you know if this receiver can easily fit on the headband of the fatshark goggle ?

Cyb

Edited by Cyb, 13 July 2010 - 04:57 AM.

[Mr.RC-Cam]

Would it be possible to provide an antenna for the simple Rx with SMA ?

For the simple Rx, I'm leaving the antenna purchase up to the user. To combat multipathing you'll need something directional like a patch. But Terry has good results with ducky dipoles that were fashioned with a Windsurfer type reflector behind them.

Do you know if this receiver can easily fit on the headband of the fatshark goggle ?

The simple Rx's dimensions and other useful stuff is shown here: http://www.dpcav.com...productid=16559

[Cyb]

OK thank you. So it's better to go with the receiver with patch antenna.
One more question : I see in the TX datasheet that there's a +5v output on the board, can it be used to power a camera ?

For the simple Rx, I'm leaving the antenna purchase up to the user. To combat multipathing you'll need something directional like a patch. But Terry has good results with ducky dipoles that were fashioned with a Windsurfer type reflector behind them.


The simple Rx's dimensions and other useful stuff is shown here: http://www.dpcav.com...productid=16559

Edited by Cyb, 13 July 2010 - 09:20 AM.

[Mr.RC-Cam]

I see in the TX datasheet that there's a +5v output on the board, can it be used to power a camera ?

No. The 5VDC is provided on the audio cable to power an amplified microphone like the dpcav Tiny-Mic. Using it to power a camera will probably result in frustrating problems similar to what Terry encountered. To keep things simple, consider using a 12VDC camera and power it all with a small 3S LiPO pack.

[Cyb]

The problem is I already have a KX131 5V camera. How does Terry power it ?

[Mr.RC-Cam]

As far as I know he is powering his KX131 from the Tx's 5V, which is not something this design is expected to support. As you can see by several postings regarding his frustrating intermittent loss of signal, this may be what is punishing him. So, don't do it; If you must use a 5V camera then install a R/C BEC type 5V Vreg on it and power it from the LiPO.

BTW, how are you powering the KX131 on your current wireless video system? This camera needs 5VDC, so I suspect you have a VReg on it.

[Cyb]

I am currently flying with a 2.4ghz TX from Aeropix on which there's a 5V output (out of a 7805 I think).

So, don't do it; If you must use a 5V camera then install a R/C BEC type 5V Vreg on it and power it from the LiPO.

You mean that I can take another Motor controler to get the 5v for the camera ?

[Mr.RC-Cam]

Yes, the 5V BEC output on a retired ESC can be used to power the KX131 camera. Not elegant, but functional. Some ESC based BEC's can't handle much continuous current with 3S LiPO voltages and may need to be limited to 2S packs (just review the mfg data sheet).

[Terry]

I think its pot luck if you get noise on the picture using the BEC to power the camera. With good cooling I think the TX will handle the camera power but I agree that a separate 5v reg is a much safer way to go. I will make up a simple SMT 5v reg to glue to the TX for this when I have time.

Terry