1.5V to 4.5V charger

K

kam

Member
A Very stupid question, but my friend once said that there's no such thing as a stupid question. so here it is:

I want to use a garden solar light (1.5V) to charge a 4.5V batt pack for my 08M. Ultimately the 08M is gonna be in this garden light and i dont want to go over and change the batt again and again.

I know that i can use this chip LT1073... but the problem is that i cant find it in normal shops like DSE or Jaycar.

OR, is there a way to use a 4.5V solar cell... but i dont want to make it too bulky.

Any ideas, even alternatives much appreciated

Thanks

kam
 
M

moxhamj

New Member
How about this circuit http://www.talkingelectronics.com/projects/PowerSupply5vSolar/PowerSupply5vSolar.html or this one http://www.talkingelectronics.com/projects/PowerSupply5vSolar/PowerSupply5vSolar-2.html

A couple of transistors, reuse the coil etc and 5V out. There are some links there to other circuits and some different variants if you want to rewind a coil or reuse the inductor. I built one using a standard potcore but it was a bit more expensive. It does depend on whether you want 3mA or 30mA.

Alternatively, if that looks too complicated, get 3 solar lights and put the solar panels in series. Use just one of the diodes and as a bonus you lose less volts that way because there is only one diode instead of three. Put the three batteries in series. If it is going outside, it almost would be better to use the three solar light cases (as they are waterproof) and run short wires between them.
 
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M

manuka

Senior Member
I've extensively hacked ~US$2 solar garden lights for such needs,& strongly suggest you at least try similar, as couldn't buy the parts for just $2! The inductor is usually a "fat resistor" by the way - most are 470µH (yellow + purple band).

Benefits of this approach relate to both the power needs of the PICAXE circuit, & the solar resource however. Newer PVs, such as the attached, may may be easier to "persuade". Satn
 

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K

kam

Member
Thanks Guys,

As Always Prompt Replys. i'll look into em and let you all know soon

Thanks again

:)
 
W

westaust55

Moderator
Step up DC voltage converter

dependent upon your skills level and exactly what you are willing to spend, etc.
Might be possible to convert for half input and output voltages.

Silicon chip had an IC based 3V to (v converter circuit that might be modified easily.

Silicon Chip March 2004 Project
http://www.siliconchip.com.au/cms/A_100886/article.html
Click on the diagram and you can from the new window "scroll" to next and see the schematic and PCB layout

Jaycar sell as:
CAT. NO. kc5391 3V TO 9VDC CONVERTER KIT $14.95
 
J

jglenn

Senior Member
I used to make a board powered with an AAA cell, later a nicad cell, 1.2V.

Needed 5V to run a sensor and PIC chip, used the Maxim MAX756CSA from digikey, an 8 pin SOIC high freq. dc to dc step up convertor. Not easy to use, forget breadboarding, must have a proper pcb, copy their sample layout. About 80% efficient, only need an inductor and a couple caps. Very small, current limited, and reliable. And you don't have to wind any xfmr's! I think it put out about 100mA, I was using a lot less.

But I agree, using a few solar cells in series is a lot easier.
 
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