5 years ago
The easiest would be to tear apart a usb car charger
5 years ago
I actually don't recommend that, These car chargers work only at ~14V, Use a LM7805 or a cheap eBay variable transformer
Why not? That is what I have done. I use them as basic "BECs" on my quadcopter! And the one I have torn down, a dollar store cheapie, works down to around 7V before it is no longer able to regulate properly. A 780 regulator is NOT suitable for his application because his power supply is 6W maximum. A 7805 will draw 12W for the 5V 1A output.
Although, to be fair, 6W *might* not be enough many buck converters. It would have to be rated at least 83.3% efficiency under full load. (6W in, 5W out). That is do-able, but I am not sure if the cheap buck converters in car phone chargers are that efficient under full load.
That's a neat trick. A car battery is nominally 12V, 14 only when absolutely fully charged, and then only briefly. And a variable transformer only works on AC
*Variable step-down thingy-majig
BUCK power regulator !
+1 without more information.
1) A six watt input provides a current of Amps = w/v = 6/12 = 1/2A
2) A linear regulator like the 7805 cannot create additional current beyond o.5A
3) You want a 5 watt output = VxA = 5x1
4) A switcher that is 90% efficient (doubtful) would probably do your transform.
5) could you be mistaken about the 6w ?