hill all... i will questions.. how to determine resistor can be used LED with working voltage of LED 2 volt and LED series structured as much 500 LED..thanks
risky

 

Trying to understand you.
You have 500 LEDs that you want to put in one series string.
You expect each LED to drop the voltage across it by 2 volts.

Why one long string of 500?
Why not 20 strings of 25?
The voltage required will be much safer to work with.
(Less risky)

We need more information about the LEDs.
What current does each LED need?

 

LEDs current is 1 mA... and LED string series.... and only one source voltage...whether 500 leds string series and how drop voltage on each conettions LEDs...??? thanks

 

Can you post the data sheet for the LEDs?
1 ma is not reasonable. 2 volts is not typical.

This article may help you.

http://www.instructables.com/id/Simple-Led-driverConstant-current-source-20-mA/

 

oke thanks for your answer

 

2V per led and 500 in series, thats 1000V , OUCH!