Step Up Converter 3V - 5V circuit needed.

[Junkie]

I've been experimenting with Peltiers for a small portable charger. I've got the peltier rigged up in my little portable device powered off a tea light candle. It outputs 3.5V - 4V and will run my radio and a 12V computer fan for cooling slowly. Any ways does anyone know of any  circuits to step up the 3V to 5V so I can charge my mp3 player via usb ? Thanks,

[Norm]

2 Peltier units in series?

[Junkie]

I am only using one. It will mess up my design if I have to use two peltiers :-)

[dnix71]

The device here (87% efficient) will do that.

http://www.maxim-ic.com/quick_view2.cfm?qv_pk=1167

[jimovonz]

Max1708(2A) or MAX1709(4A): Step-Up DC-DC. 0.7-5.0V input, 5V output

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2307

Free samples available.

[Junkie]

Thanks for the replies. Ordered that chip, I am going to try and follow the circuits on the data sheet though I'm far from being any good at electronics. Ta,

[Junkie]

Well, I couldn't get the maxi chip here, but I found a similar thing and a circuit to boot. But I can't get it to work. The only thing I know is wrong is the diode is 1n5817 and not 1n5818 will this make a difference ? I wouldn't have thought so but ya never know.

http://foosel.org/_detail/hacks/cn8-5.png?id=hacks

[JamesJackson]

It's more likely to be the inductor that's the problem.

If that's not it - then the layout is something to check. Circuits like this can be crirital on component placement. Use the datasheet of the LT1073 as a guideline.

Also, you do not mention which version of the LT1073 you are using. There are 3 versions.

LT1073 - adjustable

LT1073-5

LT1073-12

I would assume (dangerous, I know) that you would want to use the LT1073-5 to get the 5-volts that you are wanting.

Pretty cool idea - and a cool circuit. Let me know how it goes.

Regards,

James Jackson