On Thu, Apr 10, 2003 at 12:41:11PM -0400, John Nall wrote:
> A friend (?) has given me a bag of about a 100 seven-segment LED's which

> They are 3/4" high by 3/8" wide, red in color.  They are in the shape of
> a 14-pin IC.  Looking into the face, there are two indentations at the
> bottom and a single indentation at the top, with a dimple at the top
> left (probably to identify pin 1).  Assuming this is pin 1, then there
> is a pin 1, 2, 3 and 4.  No pin 5.  Pin 6 and 7.  Continuing to the othe
> side, there is pin 8, 9, 10.  No pin 11, no pin 12. Pins 13 and 14.
>
> There is absolutely no marking of any sort to indicate the manufacturer
> or  the model number.  (I have examined it with a magnifying glass under
> a strong light).

John,

It takes less that two minutes to ID all of the pins. All you need is a DC
power supply and a current limiting resistor. Make sure that the resistor
won't pass more than 10ma of current when dropping the whole voltage of the
supply. So for 5V use 5V/0.1 -> 500 ohms (470 is fine). This will light the LED
but protty much guarantees that it won't blow out an LED no matter the
current rating.

Create a probe by tying the resistor to the V+ lead of the supply, and a lead
to the GND. Take one end and tie to pin 1. Drag the other across all the other
pins. If any segment lights up then you have a starting point. If not then
move the fixed end from pin 1 to the next pin.

Generally within 30 seconds you'll get a segment to light up. If the floating
end of the probe lights up any other segment, then the fixed end is the common.
Otherwise the floating end is the common and you start IDing with the fixed
end.

In any case you can completely ID the entire display in about 2 to 3 minutes.

I never both keeping pinouts on LED displays because they are so easy to ID.

BAJ

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