Determining specs of LED display without a datasheet

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,167
I purchased an UXCel 1" 7 segment display on Amazon. They're from China apparently. 5 parts for the price of 1 similar part on Digikey. Never have made a purchase like this before. However, there was no datasheet. Is there anyway of making measurement that will allow me to calculate Vf and I?
 

ScottWang

Joined Aug 23, 2012
6,873
You can using 2V/20mA to test it, if the brightness is enough then just use that value, otherwise you can increasing the current a little more to test.

And this kind of 7-segs led, when you do the testing, you need to using some plastic(or glass) color paper to cover it.
 

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,167
Thanks for the process. One question: the 1" displays on Digikey (LDS-CA14RI) that look similar (horizontal versus vertical pin layout) look like their Vf is 4V. Am I reading the datasheet wrong?
 

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bertus

Joined Apr 5, 2008
20,319
Hello,

To determine if there is one or two leds in a segment use a 5 volts powersupply and a resistor of say 220 Ohms and measure the voltage accross the segment.
This would be safe for 1 led in a segment as the current will be (5-2)/220 ≈ 14 mA.
For 2 leds in a segment the current will be about 4.5 mA, wich will still give a visible segment.

Bertus
 
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