Published:2012/9/18 21:33:00 Author:Ecco | Keyword: USB, Power Booster | From:SeekIC
As you probably know, the USB 2.0 ports can deliver up to 500 mA, that means about 2.5W. But sometimes you might need more power to connect an external HDD or other peripherals and the USB ports just cannot deliver enough current. In this case you can buy USB hubs that have an external power adapter required to boost the power or you can build a simple or complex circuit that can do the same thing.
There are many usb power booster projects available on the internet, some of them are very complicated, others are simple as using a few components. One simple design involves the use of the 7805 voltage regulator that can deliver 5V and 1A.
Circuit No 1I have found this design on Electronics For You website and it uses the 7805 regulator, a MOC3021 optoisolator as main components. (source)
Circuit No 2This is another design that uses LM2575-5 step-down switching voltage regulator. Its principle is that internal power transistor switch on and off according to a feedback signal. This chopped or switched voltage is converted to DC with a small amount of ripple by D1, L1 and C2.
Circuit No 3This usb power booster circuit is the simplest one and it uses the 7805 voltage regulator that can deliver up to 1A.
Circuit No 4It uses the same 7805 but with 2 external transistor it can deliver up to 3 amps, that is 15W of power (source).
Of course you will need an external adapter to power up this circuits, something like a 12V DC adapter. What do you think?
Source: electroschematics.com
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