Strange Grounding Problem Need an Expert HELP

[kreston]

Hi there!

You've heard Philips Ambilight. I was thinking to do that with my pc and I found this circuit and i made it.

**broken link removed**

There was transistors where the resistors end. And with those transistors i could change 12v RGB LED MODULes brightness. I mean i could get any color with those leds from computer.

Well then i changed the circuit because it was my first attempt and it was kinda big. And leds were not brighty.
So i redesigned the circuit. I was using 5v and 12v supplys seperated.i mean 5v was coming from usb and 12v was from adapter.

So in this new circuit i thougt it all could be from 12v. I mean the only supply will be 12v from adapter

**broken link removed**

so i used lm7805 like the picture above.

And after this,things getting complicated. 16f628 and max232 seems working fine. But leds are not working.

When i touch top of the 16f628 leds are working I think there is a problem with the ground because when i touch leds ground its working better(i mean there is no flickering when i touch)

But i don't know why. What can i do?

 

[banjo]

It sounds like the 16F628 is operating erratically or continually being reset. Your circuit does not show the +12V circuit. I am assuming that this is driving the LEDs.

Have you measured the +5V out of the 7805? Is it stable?

Try disconnecting pin 3 of the 7805 and connecting the +5V back to the USB power connection. If the circuit works fine, then you know it has to do with the 7805 power source. Perhaps the regulator IC is hooked up incorrectly or your filtering is not sufficient.

If the circuit is still wonky with the USB power, then make sure all your ground connections are well soldered. The high current ground return of the LEDs, should not run through the same traces or wires that are powering the 16F628 or the RS232 chip. If these chips see lots of noise on the ground trace it can make for erratic operation. The ground connection should be a star pattern, not a daisy-chain. The center of the star is your power supplies. Then individual ground branch off independently.