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charging circuit design
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Engineering & Manufacturing > Electrical

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The client has made the following changes to the job.

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Jun 16, 2011
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Job Description

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  • Posted: Wed, Jun 15, 2011
  • Time Left: Closed
  • Location: Anywhere
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  • Start: Immediately
  • Budget: Less than $500
  • Fixed Price Job
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  • U.S. freelancers must have W9
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I have 6 solar cells. each is 5.5v (max efficiency) at 150mA

I would like to wire them to a USB jack to charge my iphone.

I've built several mock ups, at a very simple design. some with a regulator but I do not like as I have to wire them in series to accommodate for the voltage drop out. This also then drops the amp to 1/2 whats possible

I have then been testing a bunch of designs using a step up regulator MAX756, various capacitors, resistors and diodes.

I feel like I just lack the complete knowledge to get what I'm after.

The main issue being that the panels operate at the 5.5v 150ma at peak efficiency, which is the first 20-30 minutes in full sunlight. After this amount of time they drop to 4.5v range and will no longer charge.

I would like to avoid having to design a battery into the system. And would like to get as many amps as possible to facilitate charging quickly. I could even go to 9 solar cells.

I would like to use elements that minimize the need for heat shi...

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Job ID: 24738061
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Mark B.      
Mark B.'s identity has been verified.  Learn More
 United States  |  
INVITED
Mark is currently a consulting engineer working in the field of Solar Photovoltaics (PV). In 2011 he started his own company DC to Power to assist...
1
  |  
 4.9   |  $1,422 Earnings   |  14 Jobs
Bid ID: 24747849  |  Submitted: Jun 16, 2011 01:08 ET 
Proposal SEALED
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