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RPi 5V PSU construction
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▪ 1 A 5V power supply for the Raspberry Pi - Construction How To
▪ 1.1 Resources on 7805
▪ 1.2 The testing prototype
▪ 2 Other PSU options
▪ 3 Mobile battery power supply options
▪ 4 Over-voltage protection
▪ 5 References
A 5V power supply for the Raspberry Pi - Construction
How To
Due to various problems with the power supply for the RaspberryPi, a home made PSU
might be a solution for some of you. You will need some experience with construction of
electronic circuits, appropriate tools and a multimeter.
I have had problems with a cheap 5V/1A adapter from Ebay too (freezing, no LAN, etc.)
... The adapter could not provide enough power. It had 5.0xV unloaded, but with
RaspberryPi connected I've measured 4.78V and less - dropping to 4.5V on TP1 and TP2
[1] , and that's not good. The voltage drop might be partially caused by the cable, but I've
used a branded Nokia cable that looks pretty solid. Anyway, we have to compensate for
that too. Also there is some voltage drop on the polyfuse F3 (typically 0.1-0.2V, fuse
should have about 0.2 Ohms [2] ), hence don't expect to get >=5.0V on TP1-TP2...