Overlay texts and graphics too transparent,almost invisible

[karelium]

Hi All,

I’ve just got the Video Experimenter board. It’s really cool. I’m planning to use it on a cuadcopter project to inject real-time flight data and even a very simplified version of a map or radar.

The thing is the overlaid text is too transparent. I tried with a couple of monitors: a big tv, overlay is too transparent and a small TFT display with analog input on which the texts were invisible.

Switching to Sync Only(without the input video on the background) displays the text very clear on both monitors.

I read on a post, the circuit adds 1v to the signal whenever there is a pixel. It seems it’s not enough on certain signals/displays or configurations, I don’t know.
Anything I can do? Any way to rise the voltage to make the pixels more opaque/visible?

Thanks a lot,
Karel

[Michael]

You can try increasing the voltage by reducing the resistance of the 330 ohm resistor. Reduce the resistance by adding another resistor in parallel with it. For example, another 330 ohm resistor will give an effective resistance of 165 ohms, and this might make the white brigher. Maybe connect a potentiometer in parallel and experiment to see if you can make it brighter white (but be careful not to completely short the connection across the resistor.

[karelium]

Great! I’ll try it out very soon and post the results here.
Thank you so much.

[karelium]

It worked !
I added a potentiometer in parallel as per your suggestion, when the resistance was around the 250-300 ohm the overlay began to be noticeable brighter and brighter! I finally replace it by a normal resistance for the same ohm value. Very happy now.. experiments are ongoing.

Thanks,

[Michael]

That’s great to hear. Have fun!

[Author]

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