Prateek if u want I can build u a setup consisting of regulator ie 7805 n filter ie ( Capacitors Connected in Parallel Circuit). I often make use of this Ckt in embedded systems. Its a very small ckt bt I think ll solve ur problem to a great extent. Don worry bout the charge I wont charge anything, only U ve the Pay the Shipping cost.

OP I liked this mod so much, I had to do figure out the way.

Last night I did some experiments and found these.(Please see the attached pics!)

Issue 1 : Discharging Lipo under 3.7v

             > screen draws only 150mA
             > Rx draws only 200mA on 2S and ~214mA on 3S

             So even with small 1000mA battery you should get close to 170 minutes (Almost 3 hrs - Plenty IMO) run time.
             STILL LIPO ALARM IS ALWAYS A GOOD IDEA!

Issue 2 : Rx gets too hot on 3S. Cant power both Screen and Rx from same 3S Lipo.

            > miginstruments suggested since there are already holes on back of the screen,
               decent heat sink and/or small will do the trick. Gr8 idea but thing is we are trying to make it more compact.
            > Another easy solution is power both Screen and Rx with different batteries. But wht the hack we trying to
               make it look cool not bulky!  
            > OR introduce the 12v to 8v circuit, with only 3 components and some soldering, but agian as miginstruments
               suggested we are facing the issue of over heating the IC7808. back to square one  

Issue 3 : Well not yet, let me create one.

            > so around 3:30 in the morning   I found this AMS1117 on the circuit board of the screen.
               Its a simple low power voltage regulator. and as you can see below the two rails outputs 3v and 5v.
               So decided to use it to power the Rx with it,   praying i dont fcuk up anything on that board and it did work !!!!!






             > SO NOW THE ONLY ISSUE IS ITS ONLY DRAWING ~138mA.



             > I ran this setup for around 20 minutes, before one of the wire got loose. But nothing really got HOT.
                Actually the voltage regulator AMS1117 on the ckt board did not got as hot as it was getting without taking 5V out!
                

 ? But now the question is that 138mA gonna be a problem?
 ? Is it going to Lower the effective range of Rx?

well u shd do a bit of more research on the board ur uscurrentng. Check out for its rated current, it has to be greater than 138 ma. Moreover at this time the circuit behaves in a different. U ve to check out it in daytime. Tat time temp ll be more n may be the screen ll consume more power. But if its below the rated power then its fine. Now the question is to protect the lipo, so u can use an alarm to avoid max discharge. I spoke bout a fan, its pretty small n may get fit without consuming more space. Though it ll also consume some power but believe me heat is a great enemy of circuits. So u can afford to lose some power in order to protect the entire setup.

Running the Rx off that smd regulator is a bad idea.

Wow, Chils41 how come you didnt damage your Vrx, while using it without an antenna?Or is it only applicable on Vtx ?
And can that be the reason for reduced current consumption?

And I think that adjustable regulator is rated for 800mA.

EDIT
Just wanted to add, I think the Vrx too would be having a linear regulator onboard to get 5V, so wont supplying it with 5V be kind of undervolting it. Most of the 5V regulators need atleast 6.5-7V to work AFAIK. Moreover RC305 Vrx works within the range of 7V-12V.

Car cellphone chargers to convert 12v to 5v on my GCS setup...They're pretty light, do not get hot (smps, not linregs), inexpensive and easily available, deal with voltage spikes pretty well and are capable of delivering 0.5 amp easily, I've been running a raspberry pi with them on my diy GCS

http://www.rcindia.org/self-designed-diy-and-college-projects/flying-on-a-3d-joystick/msg163071/#msg163071

Nice project. But please dont mind, you have a sloppy soldering. I would rather blame it to the ROHS compliant solder used in the Boards, which have a relatively higher melting point than the usual 40/60 solder we use form DIY/Repairs. Get a raw / brute sodlering iron of preferably higher watt and let it get heated covered inside a metal can (specially in summers we put fan on.)
Put some Flux and then gently touch the tip to the board and solder the wire. The result should have a shiny and blobby solder left on the board and not a dull 'Muddy'
I have spent days debugging such 'Dry Solders' on my PCBs during my early school days when I was getting into Electronics/HaM radio..

U can Use Sponge dipped in water to clean the tip of the Solder Gun. keep cleaning the tip after every single time u use the Gun. Also before soldering a point clean the tip, just rub it over the wet sponge. Moreover the Lead ur using is quite thin, i think tat is of Maxx brand, n it is used for soldering mobile phone ckts. Try to get a little bit thick Lead, it holds the soldering point pretty effectively.

It might be no doubt, but hey somebody gotta do it, so that other dont have to repeat same mistake.



Yes SideWinder, YOU MUST NOT POWER VTX WITHOUT ANTENNA, because it must output all that power via polarization. with Rx you are just fine.
And I THINK current consumption is still the same after hooking up the antenna. BUT WILL CHECK IT OUT AND POST IT LATER.
The regulator is rated for 1A, and I cant measure the current its outputting to the board without de-mount from pcb.

Yes the Rx also has 5v linear regulator onboard, and yes I am definitely under powering it with 5v supply.
And that is the main reason I want to do RANGE TEST to see if that made any difference.



you have one hack of a project there. very very impressive.
I tried to do something similar using Arduino, but programming USED TO BE my thing back in the days,

I guess first I have to brush up on that first, any way project was to use ball-bearing gimbles and some switches hook it up to Arduino
running Tx code, and generating PPM fed to Orange Tx module. Making your own custom Tx.

But hey thnx for the input.


Agree! This is my first time actually soldering something. Other than this I only have used solder to connect the Bullets to ESCs!!!
And I guess I need better solder iron. This cheap $3 menards one was just lying around. And yes the good soldering station is on my wish list.
PS: I never get that shiny solder, its always tht dull and muddy, I wonder the cheap Chinese 2% flux solder wire has to do something with it !!!



You are ri8 man, I havent cleaned tht sucker forever, and using that I have made holes in Foam, plastic and wht not. so its very dirty indeed.
Dont know wht brand that is, cause all the letters r in chinese except it says 2% flux. but I will get some thicker material.




Thnx OP for this MOD and Thank you guys for all your inputs!!!

Yes sire, the water sponge is absolutely necessary and so is flux, the idea is to heat the surface and melt the solder on the surface rather than the tip flux helps remove the impurities and improve solder flow (you will automagically start getting shiny solders when all surfaces are clean)... if your soldering iron tip has gone black, get a new one, it should be shiny silver... And no melting flux directly onto the solder tip and absolutely no sanding of the tip :>)

PS: thanks for the appreciation, the project still has a lot of work left

LOL no sanding of the tip.

I was thinking about go home and clean it with wire scrub, i ll just get the new tip.
and I think I will get 60W iron and some flux as well.
You think I really need temperature controlled soldering station for this,
or just cheap iron will do the job, with nice tip and some flux.


PS: hey are you good with programming? I am talking about Arduino

Scrub it against the water sponge (let the sponge be completely wet in water), the moment you see some silver tip, melt some solder on it, and wipe again on water sponge, repeat and repeat, and you should soon have a clean tip again... You want the tip to be clean at all times, do not use flux for the cleaning process, it will make things worse and leave the tip tarnished

Temperature control, not really required, you might want to try soldering some other stuff first but for the project you're doing, a fine tipped should be alright. and you don't want the tip to be overheating the pad, thats where  the temperature control comes in

there is a brand called Solderon ( Yellow in color) believe me I am using this Gun for years. This is one of the best quality Guns available in India. n keep two separate tips for soldering n making holes in plastic or else u ll destroy the tip.

Thank you both u guys girishsarwal  and miginstruments
I just ordered 60W iron, as now I am sure my iron wasnt getting hot enough to do the job.
and will pick up some extra tips on the way home since the old one is pretty messed up already.

and for now I m going to use two separate battery to power Screen and Rx.
by the time I receive the 12v to 8v converter IC, let me drill a couple of holes on the side, and break out those AV OUTs.
also a little hole on top to switch b/n channels.

  on Soldron. Weller, Stanley, Tekton, J&L would be popular in the US
All the best

I dint really check tht, but THIS IS WHAT I ORDERED and it happens to be J&L. cool.

Oh and by the way this is the solder wire I am using
0.6mm 50G 65ft 63/37 Rosin Core Flux 1.8% Tin Lead Roll Soldering Solder Wire
Its cheap I kno, but hopefully its alri8.

63/37 Sn/Pb is alrite...

Good and HERE is the Flux I ordered.

Chils since you are at it you can as well try to bypass 5V regulator on Vrx. It may solve your 138mA current draw issue. It has been tried earlier so to speak.
http://www.rcgroups.com/forums/showpost.php?p=20996467&postcount=3

kewl! Just what I needed.U made my day man.
So now all I need is good solder joints, which I think I will be able to since now I know a lil bit more about soldering.


Next few objectives in this project.

> Instead of TWO AV Outs, One more AV Out connected to Screen's AV2 In, so that screen can be used with something else!
> A Switch to power on/off the Rx, when in/not in use.

I do programing for 8051 but haven tried for fcb. I am thinking to ve some hands on tat too. But it ll take some time cuz am a bit tied up.

Got a lot to learn from this thread, thanks guys!

you ri8 bout tht man. But hey u the one who brought it up.
Its takes one idea to start the things, and many brains to make it work!

Chils, so I re-read the entire post with more time on hand..

1. Whats wrong with 138 mA or 200mA?

2. its pulling ~200-215ma on both 3s and 2s, so its rated for that. Current is a function of load, its pulled, not pushed into circuits. Imagine a rope on pulleys and a weight attached, higher the weight faster will be the movement of rope ... the load determines the current that flows, not the power supply 

3. It's getting hot with a 3s because the vreg has to get rid of 12v-5v = 7 * 200mA ~ 1.4W of energy vs 7.4v-5v = 2.4 * 200ma ~ 0.48W of energy. Put a fan, heatsink, necessary ventilation, all should be well.

4. Yes, the Vrx does have a linear reg inside, its min voltage is 7v, that is exactly what a 7805 needs to deliver 5v... see attachment, you can run safely between 7v and 12v. Check out the supply current 

PS: yes I do program Arduino but I've always liked the AVRs the native way using assembly and C