I want to install small LED 'lamps' to each room to provide minimum lighting in the event of a power failure ( a regular thing in our country ). My 12vDC system runs off a UPS, so was thinking that using LEDs the best option due to the little current they draw.
I have found a local source of small 4 LED bulb lights ( typically used in cupboards, etc ) which supply enough light for me to see my way around in the dark. They are powered with 3 small AAA batteries ( 1.5v each ).
My thinking is to replace the batteries with an on/off switch connected to my 12v supply and a 7805 regulator to drop the power to 5v.
Which of the following would you consider the safer option ( in terms of wiring heat / potential damage / danger, etc ), considering the wiring will be running from my supply to each room through the ceiling :
A. run the 12v from supply to the room, then have a wall mount box containing the 7805 and on / off switch ( one box in each room ), or B. have a single 7805 at the supply source location, and run 5v to each room with only the on / off switch the wall mount box ?
Also, for the 7805, I have read conflicting information :
- that the 7805 can be used as is to drop the 12v to 5v,
- that one should add 2 capacitors to the step-down circuit.
Which is the correct method ?