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Topic: 1.8" seven segments displays on ebay (Read 1691 times) previous topic - next topic

1.8" seven segments displays on ebay

Hello,
I have bought a set of 5 x 7 segments display 1.8" from ebay
http://www.ebay.com/itm/401125308735?_t ... EBIDX%3AIT

I received them today. I found no datasheet for those displays on any website using google. Also, when I tested them using my Fluke multimeter, I found that only DP (decimal point) LED works. When I tested using a small power supply (3V3 and 5V using a 100R resistor), my fears have been confirmed. Despite the fact that those displays comes with a film on them suggesting that the displays are new, only the decimal point is OK on them. Seems those are rejected displays and are sold on ebay as new ones. (I checked all the 5 displays, same behaviour for all).

Did anyone had experience with them please?

 

Re: 1.8" seven segments displays on ebay

Reply #1
I think some of the bigger displays like that have 3 leds in series, try them at 12v with a current limit resistor.

Re: 1.8" seven segments displays on ebay

Reply #2
Hi blarson,
thank you and good point about the 3 LEDs serially associated. Effectively, the DP led triggers from about 3V3 and all other segments can be triggered from about 7V5 (at 9V they looks pretty good with 1K limiting resistor). I also checked some datasheets for similar sizes displays from other chineese manufacturer and almost all of them confirm your post, DP is almost always 2 LEDs in series and all other segments are 3 LEDs in series. This explains the behaviour I'm experiencing. Next work to do for me is to check and measure those LEDs arrangements correctly and do all current consumptions in order to (calculate and) use the correct limiting resistors.

Re: 1.8" seven segments displays on ebay

Reply #3
Here is what I received from the vendor :~(

if I understand from the images, from a personal guess, I think it means that each segment is 3 LEDs and the DP is 1 LED only.

If any person on this forum can read chineese, can you please translate the image texts?

Regards