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 FORUM :: DakarOSD/Lynx RC Plane OSD
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 Subject :Lynx V2.1 - R10, R11 & C9.. 17-01-2010 12:29:45 
IanJ
Joined: 31-10-2009 16:59:00
Posts: 4
Location: Stonehaven, Scotland, UK.
 
Hi,

I had a personal message with the following query. Here it is, and the answer.

Quote:
I have a question: looking to your lince pcb scheme, I have noticed a mod near lm393, on pin 3 (R10,R11,C9), also the potentiometer value is different from original scheme. Why do you add this modification?
Thanks
Francesco


Regarding R10, R11 & C9......this is a good question, as follows:

When I first hooked up Cristobals Lince circuit with my video Rx etc I could not get anything to work. I could not get the LED to turn on thus no data. When I looked into it I found that my video signal had some DC offset that the LM393 could not reach even though the pot was turned from one end to another.
So, I changed the design by ac-coupling the video input via C9 and using R10 & R11 to bias the video signal to about 2.5vdc, therefore the potentiometer is adjusted to about 2.5vdc also. This now works great with all different makes of video Rx.
I have come across 2 other people who had to make the same modification.

Regarding the potentiometer, it's not important 5k or 10k etc. Probably just what I had in my spares box....:)

Ian.
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