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How to get 5 volts from 4xAA batteries? Answered

Hi all! Whats the best way to get a nice circuit friendly 5 volts from 4xAA batteries?
Measuring some brand new AAs, they're about 1.6v when new, which drops under load, I know. So four AAs of course add up to 6.4v, possibly blowing my low current circuit.
And isn't a 7805 voltage regulator only good with aroundabouts 7-8 volts source because of how they work?
Plus DC-DC converters are expensive, and resistors are wasteful. :-)

5 Replies

luxstar (author)2012-09-02

Here is an instructable using a DC to Dc converter:





The data sheet says the input voltage can be 4.5 to 14 volts. The output can be adjusted from one half volt to 6 volts. This converter should work in you application but if you could add another battery or two you could have some really good run time. The cost for this converter was a little over $8.00 but it is the best solution. Murata makes several different devices for different current / wattage requirements;




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AndyGadget (author)2010-08-30

If you're not after a regulated supply and just want a voltage drop, jput two silicon diodes (e.g. 1N4148) in series with the batteries. This will give you a drop of around 1.2V so you'll get 5.2V when batteries are brand spanking new, quickly falling to 4.8V for the normal service life.
I've used this technique several times but check your chips' spec to see if this is in range for what you're using.

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NachoMahma (author)2010-08-18

.  What makes you think the circuit won't handle about 6V?
.  Use NiCd batteries. They have a nominal voltage of 1.2V.

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steveastrouk (author)2010-08-18

Use 4 batteries and a LDO regulator - Low Drop Out - they'll work with much lower voltage drops than standard regulators.

An LM2940 is one part, some LDOs will work with a difference of 0.5 V.


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frollard (author)steveastrouk2010-08-18

Another option is a mintyboost style boost converter that can joule-thief enough current from a single AA -- especially if the OP is not exadurating about 'low current' :)

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