Hey there, I'm working on a personal project, a large LED light board, I have a bunch of shift registers driving a bunch of darlington arrays, afaik this part of my circuit is working a-ok (driven by an atmega).
Now the board is going to have over 75 parallel circuits of LEDs, which means I have a rather high current circuit. I'v started building my own Power supply for this shindig, and my schematic for it is:
My problem is the specifics... I'm not sure of the resistors to be using.
for the technical details:
Transformer drops the voltage from 240v to 15/12v
Bridge Rectifier is connected to the 15v, and outputs @ ~13.4V DC
the weird thing now is my 7805 on the one side is pushing out 4.2v, and , with a 3ohm resistor in place of r1(got this idea from the 7805 datasheet), my output on the second supply is 12v.
I've been trying to do this on my own, but now that things are finally starting to come together and I can test things with the multimeter, I believe I may have either missed a step or doing it all wrong.
I would really appreciate any help anyone can offer for this, if you need more #'s just let me know.
Oh.. and: The purpose of the two circuits is to seperate the high current LED board side, with my shift-reg/microcontroller (low-current) side.
Now the board is going to have over 75 parallel circuits of LEDs, which means I have a rather high current circuit. I'v started building my own Power supply for this shindig, and my schematic for it is:
My problem is the specifics... I'm not sure of the resistors to be using.
for the technical details:
Transformer drops the voltage from 240v to 15/12v
Bridge Rectifier is connected to the 15v, and outputs @ ~13.4V DC
the weird thing now is my 7805 on the one side is pushing out 4.2v, and , with a 3ohm resistor in place of r1(got this idea from the 7805 datasheet), my output on the second supply is 12v.
I've been trying to do this on my own, but now that things are finally starting to come together and I can test things with the multimeter, I believe I may have either missed a step or doing it all wrong.
I would really appreciate any help anyone can offer for this, if you need more #'s just let me know.
Oh.. and: The purpose of the two circuits is to seperate the high current LED board side, with my shift-reg/microcontroller (low-current) side.