Should work just fine.
I have a number of older external hard drives that use a single 12 volt input but then have an internal regulator inside for the 5 volt power source.
ah... ok thanks. I was thinking since this puppy can supply 15v @ 5A maybe i can get away with using a 2A or 3A 12v Regulator and powering the 5v Regulator from it... Like:
The 12 volt regulator will have to dissipate a little more but the 5 volt will dissipate less so the average will be more balanced out between them for individual losses.
It would be my choice plus if the 15 volt source ever got replaced with a 12 volt one the first regulator could then be eliminated all together.
Ah yeah thanks! This will be my plan then... at least i have the schematic ready for a small PCB heh... just need to make a nice 4 PIN for wires heh... and a Barrel Jack and perhaps a Bridge Rectifier ...
I altered the schematic and will make a new board. Perhaps its heating up because im powering it from the 12v LM7812 ? So its drawing to much from 1 regulator. Here is the new schematic
Given that both are linear regulators the total power dissipation will still be the same regardless of if they are in series or parallel with each other.
if you are supplying .9 amps at 12 volts from a 15 volt source you get (15 - 12) * .9 = 2.7 watts. And (15 - 5) * .65 = 6.5 watts.
So the total dissipation that way is 2.7 + 6.5 = 9.2 watts.
If they are series you get (15 - 12) * (.9 + .65) = 4.65 watts. And (12 - 5) * .65 = 4.55 watts which means that 4.65 + 4.55 = 9.2 watts again.
I suspect your heat sinks may simply not be large enough for the peak losses involved.
Yes I am aware of that but I went by your post 5 where you mentioned using 2 or 3 amp regulator for the 12 volt circuit.
ah... ok thanks. I was thinking since this puppy can supply 15v @ 5A maybe i can get away with using a 2A or 3A 12v Regulator and powering the 5v Regulator from it...