Maybe the PSP-PSU is just too good!
As said I tried resistors, with no difference. Maybe there is built in voltage detection? Adding too much resistance I think could make it more unstable though, it probably has the limits of a regulator. To low voltage/too much adjustment and it just can't deliver the specified voltage any more.
I'm going to boot it as soon as my SD card is ready (hope it work, took it from a digital camera which is replaced by EOS 30D).
The PSP charger is rated 2 A at 5 V, and it seems to have no problems delivering it! Looks like a quality PSU.
Just so you know, I don't have a strict budget. I would gladly spend 2x more on better quality components. 
r4049zt wrote:My keyboard did not work off 5.4V nor 5.3, from four AA batteries. The rPi booted safely but keyboard was not working. I had to run them down to 5.25V to get less than 4.99 Volts on the rPi board. I think that the component D17 which I test at is connected to TP1 and TP2. So, you are about 0.4 Volts too high.
Another way to do it would be to solder a >= 3Amp rated silicon diode onto one of your test points and run cable to there. The 0.7V diode drop would be about right but since it dissipates half a Watt, it might get rather warm.
I'd extend your cable, and bear in mind that 4.8 to 4.9 Volts on the rPi board is what I get with an approved 5V 1A power supply from RS.
I tried to plug in a keyboard, it didn't work. I figured its USB-ports was not powered until the boot started.
I don't want to ruin my test points, and also I want to keep the voltage above 5 V (>=5 V).
1 A is way to low for me, I need at least 3 A. But also, I would need at least 6-7 V into the regulator, right? It's just not a good option for me, then I can't use that power supply anyway.
redhawk wrote:Schottky diodes i.e. IN5817 would work better than silicon in this instance because their forward voltage drop is 0.3v which should reduce the supply output from 5.4v to 5.1v which is in spec for the PI.
Richard S.
Seems like a better solution.
That would actually be perfect. The voltage would end up as 5.05 V.
Unloaded anyway.
mahjongg wrote:A few remarks for late comers to this thread, using a 1A 5V regulator should work, even a primitive one such as the LM7805, however when using that particular type you must input at least 8V to the regulator! And in that case you also need to put a heatsink on it.
A better solution would be to use one of the many 5V 1A (or more) low-drop regulators, that can work with input voltages as low as six volt, some work with even just half a volt over the output voltage.
Hmm, I was thinking 7 V was a reasonable guess, but you're probably right.
Also, when using such components you're wasting some of the power (not much though for a little Pi).
Maybe I have to use a low-drop regulator when fitting a battery into the case. In this situation I actually do mind the power waste. They're not efficient, and it's stealing some voltage. Not much thouch, but enough to steal one hour in my setup.
So is there a better solution dealing with batteries. I need 9 V for something in my Pi project also, but I can't remember why though.
I believe it was something smart!
I need a efficient way of providing 5 V from batteries to my Pi.
I am not afraid of unnecessarily complicated solutions, nor the price tag. So maybe I could make a power supply that also takes care of the battery, a efficient one.
Any thoughts? I don't care if it costs 5 times more than my R-Pi!
