7805 troule

[mbarazeen]

why do you need to use a regulator before LEDs? what if you connect them all to the direct regulated source with different resistor just to limit the current?

or connect all the LEDs in series and use a single resistor to limit the current. what your circuir basically does is just power the LED when there is a source power.

 

[Dragon Tamer]

First you need to add a massive heat sink to the 7805 and probably a fan as well, second I just have to know why do you need to run 8 LEDs with a 7805? You need to increase the resistor values. I would start at 1k and slowly work my way down, right now you are drawing 320mA from the 7805. Looking at the data sheet the output is limited to 1A, although in my personal experience they are limited to the total current from the power supply (ie: 500mA= 500mA max). If you are trying to draw too much current, you may have destroyed the 7805 if you didn't do it with heat alone. Try a new one and start slow.

You should measure a known output voltage of the upper portion of circuit, then connect the 7805 and see where your voltage goes in said circuit section.

 

[audioguru]

Since your unregulated supply is 28V and the blue LEDs are 3.2V then connect the 8 LEDs in series and in series with a 62 ohm resistor for 40mA.
You don't need a voltage regulator for LEDs.