Recently I had a lot of problem carrying my FPV screen around with the hood and receiver post on it, so decided to try and integrate the 5.8GHz rx into the screen itself.
The screen and fpv system are from www.quadkopters.com

I first opened the RX and removed the casing. I found that the board itself is not that big or bulky, it contains only a few components other than the 5.8G module. Next I opened the Screen and found the correct spot for fixing the board.

Using a multimeter I found the correct pads to solder wires between the screen circuit and the RX, soldered all the wires, applied some industrial isulator tape and fit the rx circuit directly to the screen.

More pics

Clever, I have the exact same screen and I believe that is Boscam 5.8 Rx, Gonna give it a shot.

Very very Clean build. I am not a fan of velcro either, had to stick my Rx behind the screen and run those bulky wires around.

The Rx gets pretty hot on 3s. The Rx case acts as a heatsink, but since you removed it, drill some vent holes on the LCD cover.

This thought came to my mind as well. You seriously need to make some holes in the back panel of the screen. Otherwise it might damage your screen or damage itself.

you guys are ri8, the Rx is getting hot on 3S battery.
First I thought let me use some kind of Voltage regulator circuit.
But it will be a lot of extra work for just a simple issue.

But then Volla!  Here is the easy fix.

USE BALANCE CHARGING PORT TO POWER THE Rx.

I ordered 3S 4-Pin female connector. And will connected as shown below.

won't that be unbalancing your Lipo badly with every use?

You will need a special balanced individual cell charger every time to revive the LIPO That's if you don't end up over discharging your LIPO on your RX and Screen.

Worst thing about using lipo for RX and GS is that if don't watch it, it will invariably over discharge your LIPO below nominal 3.0 per cell that too at less than 1C rate of discharge and that's clear discharge. The cells won't even get back the min 3 Volts even after removing from the load thereby suffering irreversible permanent damage with every use. 

The LIPOs used for GS and Tx/ Rx tends to get bad fast.

There are holes behind and I have made some more, both the rx and the screen are connected in parallel using one battery. If its very hot then I may install a small cooling fan as well.

There is an insulation backing between the screen and the rx to prevent heat to damage the screen

Prateek can you put up a pic with the screen working. Just wanted to see the quality of display.
A lipo alarm for the GS batteries would be a good idea then, integrating it on the screen would be better(probably on the back I guess or somewhere on the sides so that it can be monitored while in use).

@Sidewinder- Sure, I'll send in the evening(My new GoPro is coming! Really excited  )
I'll need to buy another alarm but, I'll need to rewire it to fit it inside the panel.

Use of Lipo voltage alarm is a good idea.

The Screen Back Cover ve already got holes, so U can install a small fan. Next thing is open the setup and U ll find some Regulator ICs U can easily identify them as most of the regulator ICs are of three Pins. These Ics are the main cause of Heating. Get some Heat Sink Paste from the market and apply onto those Ics. This will not completely eliminate the problem but ll reduce the heat to a good extent. Then also put a fan @ the back of the Panel. This Heat Sink Paste is also used between the heat sink fan & Processor in a computer. Try it n also do some clean soldering coz since the system is portable the wire U solded may get removed. coz rough soldering is not so rigid, n if any wire gets removed n touches any other track or solder spot of the board then U may loose the entire setup itself. Put some flux paste before soldering n try to sold the wire as near to the insulator, this will provide rigidity, n in case of movement the wires will not get removed easily.

how about introducing a simple 12v to 8v circuit with only 3 components to power the Rx.

here is the link to circuit diagram


http://schematic-audio.blogspot.com/2011/10/dc-converter-using-7808-regulator-ic.html


and since the Rx only runs on about 150mA, the IC should not turn too hot I believe.
Or just screw a piece of metal as a heat sink and it should work.

Also about Discharging battery cells below 3.7v is highly unlikely because, the 7" TFT and Rx both runs
on minimal current ~150mA to ~200mA. so say if you have 1000mAh 3S powering both Rx and the Screen,
should last you 3 hours roughly if you go with ~300mA total current drawn.
Correct if I am wrong in above calculations. I dont remember the exact current drawn, but will check it out tonight as soon as I get home.
(1000mAh/1000) / 0.300 A = ~ 3.33 hrs OR lets say both Rx and Screen draws 0.5A current it will be 2 hours.
And that is plenty of flying, if you have enough battery to fly your plane or multirotor.

Brother believe me the IC will turn hot. Its a 7808 IC from 78XX series n these ICs ve got the property of getting heated. I regularly work on these ICs. But U can apply a little Heat sink Paste n can also put up a small Heat Sink. BTW its a nice solution.

So what is the optimal solution in your opinion?
just simply use one 2S and one 3S battery? I mean this is really not a bad idea.
Because if you see only 300mAh batteries will last almost and Hour.

Bro at the end of my post I ve mentioned its a nice solution.

Still to protect your battery and also your electronics use a single battery and use a voltage alarm.
Its Simple and it works, I flew a lot today and had no problems at all.

I would consider not applying heat sink paste directly to component and leave it open without using a heat sink. The paste is just a medium to transfer heat from source to heat sink more efficiently by increasing the contact area. Heat sink pastes are electrically conductive and becomes more liquid on heating and hence flows which will create a havoc if flows over the contacts and creating short circuit. Best is to use heat sink pads like these: http://www.ebay.in/itm/15mmx10mm-cpu-heatsink-thermal-pad-premium-quality-2-pcs-15mm-x-10mm-/281261179743?pt=in_computer_components and use some small aluminium fins for heat sink.

Vijai every pc we use ve got Heat Sink applied on the back of its processor including the one u are using. This paste never melts or else U wld ve lost ur pc long back. Moreover I work on embedded systems n use these kind of things daily, n ve never seen Heat Sink Paste getting Melt, even for Years together.

Yeah I know PC uses heat sink pastes over processors and GPU. I never said it melts. It does get spread a little while heating. So applying more does cause issues. And even open heat sink pastes dont serve the purpose well as it does is gives a extra area to absorb more heat. And wont the paste just flow to the pads on pcb due to lot of vobration if left uncovered? There are lots of possibilities. Am I wrong?

Sir It gets dry day by day. I dint said to cover the entire ic with the paste. The back portion of the IC is aluminium there u can paste it. n one shld not put excess amount. Moreover its not conductive, I ve checked it by myself. I work on these things Sir so first of all I ve to be aware of the Properties of these materials.

 Heat sink paste is thermally conductive, not electrically. I even use the same thing when I change my soldering iron tips. If it does not "melt" in that application, no IC can melt it

Hmm... i thought those contains aluminium in many compounds so its electrically conductive...

@Prateek I have used a similar setup using Airwave 5.8 Ghz module which requires only 5V supplied with a simple circuit with 7805 bolted to the large metal surface. With a large metal surface you can hardly feel both rx module as well as 7805 getting hot.