LED circuit help

[ellcnl]

Please help. If I have 10 LEDs wired in series , each rated at 2.0Vf at 20mA, on a 12VDC power supply, how or can I get the full intensity of the lights?

 

[ElectronWorks]

LEDs need a voltage to switch them on (Vf) then a current through them to make them light. If you have 10 LEDs each with a Vf of 2V, you need 20V to turn them on. Once you have your 20V, you then need to limit the current to 20mA. 20mA should be enough to get them running at near full brightness.

You need a boost converter (Google it) to increase your 12V to 20V, but the boost converter needs to regulate on current, not voltage. These devices boost the output voltage until something conducts (your diodes) then regulate the output current (which you set to 20mA) Have a look at:
http://www.linear.com/pc/viewCategory.jsp?navId=H0,C1,C1003,C1094,C1766

 

[neon]

Do the math 10v at 2v each 20v right so no can do.. Put them in series two strings 5 LEDS =10v 2 is extra so 2v/.020a=100 so stick 100ohms in series 1/4 watts add the same for the other 5 leds and you got it. 10 leds at 12vdc at 40ma source is required.