Quote:
Originally Posted by ivanjt
You need to start with a 12v power supply to be able to step down to 5v. The only way to get 12v from a 5v supply is to use a DC to DC converter chip as I mentioned before.
I have a couple of units I've made from a basic 12v @ 2A supply which I put in a slightly larger case with a LM7805 and a USB socket to give me a 12v and 5v output.
|
According to the spec sheets i found, it says input voltage range is between 5 and 18V. The chip I found was lm7812 with the last 2 numbers LM78xx is the output voltage. So I'm hoping this chip will step up the voltage from 5V USB to 12V output. the specs says peak current is at 2.2A which i believe depends on the load (from what I remember from my EE days). Any ideas on what to put the circuit in so it does not look so "fugly"?
BTW ivanjt, really appreciate your help. yes, its easier to buy another AC 12 v adapter (which I found at Walmart's website for a universal one) but I want a USB one instead. I'm not looking for something that will provide enough load to use/charge at the same time. i'm fine if its just a trickle charge to get it juiced up overnight, especially when travelling.