help with batteries

[squar3d]

help me please
i am making a circuit, but have to fit it in a small space and want to minimize the battery size. the plans call for a 4 AAA battery holder. If i just use one AAA or a 9 volt will it mess up the circuit? Any help will be appreciated, i dont have much time to finish (less than a week)

 

[audioguru]

There are some very good reasons why the circuit needs 6V, not 1.5V and not 9V. It probably won't do anything with only 1.5V and will probably blow up with 9V.

 

[squar3d]

thanks so much. im trying to find another alternative for finding 6 volts in a smaller package

 

[Matt(Pic progger)]

ooookkkkkk, so what is the circuit? the cr2032 (button cell) is 3V so 2 of these will give 6V, if only a small current is needed, then you could get 6V from a 1.5V cell.... but give us more info, we can help you more!

 

[dknguyen]

Are you sure that the space taken by the DC-DC step-up converter won't be the same space you will save by using fewer batteries? it's also less efficient since you will be drawing more current from one battery and use that power to produce a higher voltage- the battery's internal resistance will cause this inefficiency.

For example, 4x1.5V cells are needed to make 6V. If you step-up the voltage from a single 1.5V cell to produce 6V, in a perfect world you will draw 4x the current and the battery will last 1/4 of the time. But in real=-life the internal resistance of the battery and the inefficiencies of the converter will cause it to last MUCH less than 1/4 the run time of 4x1.5V cells. (The more current you draw from a cell, the faster it dies...in a non-linear fashion. So it just gets exponentially worse and worse the more current you draw.)

 

[squar3d]

the circuit is a basically porzio's guitar tuner **broken link removed**
(figure 2) but slightly modified (no 6mm Jacks) its driving like i think 16 leds (but maybe like only 3 at a time) so im worried it will need the 4 AAAs

 

[dknguyen]

I'd just use the AAA. The money for a step-up converter is much more than for 3AAA, and the space used for the converter will be the space saved by getting rid of some cells. Plus it will run for much longer.

My violin tuner only uses 1AAA actually...but I guess that's what you can do if you design the circuit yourself (or or a team of engineers at a company design it for you). It runs forever too. I lost my tuner before the batteries ran out, and I have a new one now. hehe

 

[squar3d]

okay, ill just have to get a bigger container. I was hoping to be able to fit it in an altoids tin but the batteries take up too much space. thanks

 

[Matt(Pic progger)]

Gotta agree, don't try a DC to DC conversion on this, 10mins of playing, and you will be replacing the battery

Hope this helps.

 

[squar3d]

thanks everyone for your help