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Multiple power sources

dbyrd26

Sep 16, 2013
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Sep 16, 2013
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When doing a project that can use either a wall wart or batteries (such as a boombox) is it recommended to use a diode from the batteries or no?
 

Arouse1973

Adam
Dec 18, 2013
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If the batteries are primary cells, I.e non rechargables then yes you do need a diode. The diode has to have a reverse leakage of less than 1uA to conform to IPC standards. Look up ideal diodes, they are a better option.
Adam
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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If the power connector disconnects the batteries as the plug is inserted you don't need a diode.

The problem with these is that if the power goes off the batteries cannot supply power.

A solution where you use a switched plug as well as a diode allows for uninterrupted power as you insert/remove the plug, or have a power failure, combined with eliminating the losses from the diode when the external supply is not connected.
 
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