need a suggestion for a 2x AAA to 5V step up circuit

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hako90210

Joined: 11 Oct 2009
Posts: 9

11 Oct 2009 21:32 need a suggestion for a 2x AAA to 5V step up circuit

I'm trying to power a gps in a little box and only have space for 2 x AAA and a few small chips or wires.. I need min 3.3v @ 125ma as this document says .. http://www.billiggps.dk/GM-305.pdf

Does anyone have a suggestion on the best way to power this gps in the pdf with 2 x AAA.. I was looking at the LM2621 but don't know much about electronics , is this a good choice or is there something better.

I'm doing this for myself so looks, price , power life is not important.. If I can find a way to squeeze 30 min of battery life out of 2 AAA.. that would be great.

Or possibly a tiny 5V battery that would fit in the space of 2 AAA.

Thx

Kripton2035

Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth

11 Oct 2009 22:45 need a suggestion for a 2x AAA to 5V step up circuit

maxim has chips that fits your needs
for example this one :
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2307

regards,

hako90210

Joined: 11 Oct 2009
Posts: 9

13 Oct 2009 4:47 Re: need a suggestion for a 2x AAA to 5V step up circuit

Not bad but isn't the lm2621 a better choice , this chip seems to need 3.3v

Kripton2035

Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth

13 Oct 2009 8:00 need a suggestion for a 2x AAA to 5V step up circuit

you didnt read well enought ...
the maxim chip OUTPUTS 3.3 or 5v fixed directly
it works from 1V .. and 0.7v in certain conditions ...

hako90210

Joined: 11 Oct 2009
Posts: 9

14 Oct 2009 0:44 Re: need a suggestion for a 2x AAA to 5V step up circuit

well that sounds pretty good , I'll give it a shot , this is my first time trying to build such a thing. I managed to do some board level repair on a few of laptops and then I got a 300-in-1 hobby kit and I'm now I'm in electronics land , hope it works out and they include some schematic ..

Is there possibly software that will draw one for me ?

Kripton2035

Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth

14 Oct 2009 10:21 need a suggestion for a 2x AAA to 5V step up circuit

on the web link I gave you, there is the schematic at the bottom ...
if you download the pdf file on the same page, you will get the full schematic, with the calculations examples (althought there are almost nothing to calculate for a fixed output !)
regards,

hako90210

Joined: 11 Oct 2009
Posts: 9

18 Oct 2009 1:58 Re: need a suggestion for a 2x AAA to 5V step up circuit

The entire city of Toronto didn't have a max1709 or lm2621. The only
place I could have bought it was through digikey.ca . So I took a suggestion
from the guy at creatron for max756.

Looks like it will do pretty much the same. Total cost $15 with board, caps,socket ic etc..

here goes my first ever circuit schematic ... in photoshop.

Kripton2035

Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth

18 Oct 2009 9:31 need a suggestion for a 2x AAA to 5V step up circuit

maxim sends free samples if you have a pro email adress (not hotmail, yahoo etc... prefer a xx.com)
just register on their web site and order 2 samples of max1709 ...