Chespest FPV + OSD setup

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adrianatkins
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Chespest FPV + OSD setup

Post by adrianatkins » Wed May 01, 2013 8:57 pm

Hi Guys.
Today i got my cheapo FPV + OSD working.
The Video transmitter is the TX5823-101016 off Ebay (200mW, 5.8Ghz).
Displayed characters are a bit shaky, but totally readable.
An external Crystal would improve it, but also add cost.
The antenna i have is a cloverleaf from Hobbyking.
You can make your own cheaper (such as here http://rcexplorer.se/diy/2011/08/the-sk ... v-antenna/)
The Receiver is so simple you can bodge it up on a bit of Veroboard.
I made two - one external, and one that fits in my FatShark Dominator goggles, both on Veroboard.
Schematic & Source code attached.
Unlike some Fake OSD designs i came across on the internet, this works.Not perfect by a long way, but it works.
Enjoy

FFS! extension .ASM not allowed. Renamed to .TXT
FPV_OSD.gif
Schematic
.
Attachments
FPV+OSD.txt
(23.38 KiB) Downloaded 193 times

adrianatkins
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Re: Chespest FPV + OSD setup

Post by adrianatkins » Wed May 01, 2013 10:37 pm

doh.
the green blob at the bottom right is an Electret mic.
Last edited by adrianatkins on Wed May 01, 2013 11:23 pm, edited 1 time in total.

adrianatkins
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Re: Chespest FPV + OSD setup

Post by adrianatkins » Wed May 01, 2013 11:23 pm

and IC1 is a 3.3v regulator, AMS1117-3.3 in this case, but any 3.3 v regulator will do.
I clearly have not thought this Post out at all

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Flaps 30
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Re: Chespest FPV + OSD setup

Post by Flaps 30 » Wed May 01, 2013 11:50 pm

You are doing okay. :)

I noticed that you have used a vintage (very ancient) transistor as the audio amplifier. I haven't seen a 2N706 used in any new designs since around 1970.. I would suggest something slighty more modern like one of the BC series transistors would be a cheaper and better alternative. My favourite type is the BC107. When high gain with low noise is needed the BC109 does the job fairly well. I do know that even they are long in the tooth by modern standards... Showing my age here.

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Kilrah
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Re: Chespest FPV + OSD setup

Post by Kilrah » Thu May 02, 2013 7:26 am

Any little video/screenshot?


adrianatkins
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Re: Chespest FPV + OSD setup

Post by adrianatkins » Thu May 02, 2013 7:57 am

Doh again.
The transistors i used were a 2N3906 on the left and a 2N3904 on the right (the audio amp).
A BC109 A, B or C would work fine as the audio amp (which is completely optional).
I dug out an ancient copy of Eagle to do a 'pretty' schematic, and forgot to change the Label.
That's also why both transistors are labelled 'Q1' !

adrianatkins
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Re: Chespest FPV + OSD setup

Post by adrianatkins » Thu May 02, 2013 9:00 am

Webshot.jpg
Here's a photo.
The two boards in the photo are the receivers.
The one on the left fits in my FatShark dominator goggles, and works exactly like the 'official' one - even the channel button works normally.
It's showing 13.5V because it's running on my Shed 12v system, not a Lipo.
The code auto-detects whether it's running on 1S, 2S or 3S, and starts flashing 'LOBAT' if the supply drops to 3.3v per cell.

adrianatkins
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Re: Cheapest FPV + OSD setup

Post by adrianatkins » Thu May 02, 2013 11:28 am

The Receiver circuit is dead simple :-
http://i669.photobucket.com/albums/vv54/alin_qq/8-9.jpg

FatShark Dominator RX module
pinout - from Top to Bottom :-

CH1
CH2
CH3
Video
Audio R
Audio L(?)
GND
+3v3
+5V

With a Sony CMQ1684L camera, the parts cost me under 70 quid
for a full Camera, sound, TX & RX FPV setup with basic OSD

adrianatkins
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Re: Chespest FPV + OSD setup

Post by adrianatkins » Thu May 02, 2013 4:32 pm

Aw c**p. Obvious really.
The 3v3 regulator will get too hot at 3S, so i'll have to add a buck converter instead.
Please wait for version II - don't build this thing.

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Kilrah
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Re: Chespest FPV + OSD setup

Post by Kilrah » Thu May 02, 2013 8:37 pm

IF your regulator is decently cooled by a nice ground plane it should be ok, the cased receivers (RC305) use linear regs and do fine on 3s.

adrianatkins
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Re: Cheapest FPV + OSD setup

Post by adrianatkins » Sat May 04, 2013 8:51 am

If it gets Hot, then that's wasting battery juice.
I've ordered some bigger 16F1823 chips with 2 comparators in them.
When they arrive i'll remove the AMS1117-3.3 and add a Buck converter instead.
We'll see if that works.
If not, big heatsink !

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Re: Chespest FPV + OSD setup

Post by adrianatkins » Tue May 14, 2013 10:45 pm

Version 2 is looking better.
i've tried the Buck converter thing and it adds Noise to the video, so decided to drop it in favour of a 3v7 1S battery to run the video transmitter.
Works better.
Sticking with the 16F1823, i used the idea of rotating the TRISC register to do the video output.
This saves a shed load of variable space.
Currently i'm trying to get it to I2C interface to a Compass and a Barometric sensor, so it can display Heading and Altitude as well as the Flight & FPV battery voltages.
I'll post a new thread when version 2 works as required.

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