LED chaser mod help - Page 2 - Electronic Circuits Projects Diagrams Free

audioguru · 29th October 2009, 11:46 PM

Quote:

Originally Posted by Space-Ace

So how can you tell?

By looking at how the LEDs are connected, or by looking at the schematic of the circuit (it doesn't have a schematic?).

MrDEB · 30th October 2009, 12:02 AM

I would think that looking at which side the flat on the LEDs are connected to should hopefully tell weather the PIC outputs are going low or high??

Space-Ace · 31st October 2009, 12:42 AM

Quote:

Originally Posted by MrDEB

what are the flat sides of the LEDs connected to?
either all together or each connected to a resistor then to a pin on the PIC controller IC.
The flat side should tell us weather the contorller is going low or high hopfully.
about 95% sure.

The flat sides connect together. The round side of each LED connects to an individual resistor, then the resistor goes to the IC.

audioguru · 31st October 2009, 02:38 AM

Quote:

Originally Posted by Space-Ace

The flat sides connect together. The round side of each LED connects to an individual resistor, then the resistor goes to the IC.

The flat side is the cathode of an LED that connects to a lower voltage for the LED to light. Since the flat sides of the LEDs connect together and to ground then the outputs of the micro-controller go high to light them.

Then you are lucky that the micro-controller can also turn on an input of an ULN2803 IC or turn on an NPN transistor.

MrDEB · 31st October 2009, 11:25 AM

parallel LEDs unless they are all the same voltage drop etc.
we is talking 250 LEDs here.
the 2803 is perfect choice but then what?
a kizillion resistors and ???
I would still opt for using the ULN2803 driving several SSR's
I think the photo showed 10 LEDs?
so 10 SSR's then xmas light strings.
EASY way out

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30th October 2009, 12:02 AM	#17
MrDEB	looking at circuit board I would think that looking at which side the flat on the LEDs are connected to should hopefully tell weather the PIC outputs are going low or high??

31st October 2009, 11:25 AM	#20
MrDEB	still have theproblem of paralel LEDS parallel LEDs unless they are all the same voltage drop etc. we is talking 250 LEDs here. the 2803 is perfect choice but then what? a kizillion resistors and ??? I would still opt for using the ULN2803 driving several SSR's I think the photo showed 10 LEDs? so 10 SSR's then xmas light strings. EASY way out