Charger Input and Output (Resistor) Question - Page 2 - Electronic Circuits Projects Diagrams Free

saumaun · 23rd March 2008, 10:05 PM

bump! happy easter, btw

audioguru · 24th March 2008, 12:19 AM

Quote:

Originally Posted by saumaun

http://store.advancedmart.com/4whredledhac.html
The output for that charger is 6.2V. How does that not fry cellphones?

For mine, if I use the 5 Ni-MH batteries @6V (7.5V off the charger lol) with this 5V regulator (http://www.radioshack.com/sm-5v-fixe...i-2062599.html) could I POSSIBLY get this to work?

6.2V is 24% higher than 5.0V. The charger circuit in some cell phones might fry if it is designed for 5.0v max.

The 7805 has a minimum supply voltage of about 7.5V. Its output voltage is lower than 5V if its input voltage is less than 7.5V.

Some 5V regulators are called "low dropout" and work fine until their input voltage is less than about 5.5V.

blueroomelectronics · 24th March 2008, 01:38 AM

Such as the LM2940

saumaun · 24th March 2008, 06:05 AM

Ah, so basically I would have to have a low-dropout 5V regulator with a supply of over 5.5V in batteries? Therefore, I could have my mystery hand-crank, 5-6 batteries and an LM2940 between the batteries and the charging cable? (well, knowing my luck, I have it completely messed up)

You guys know your stuff!

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23rd March 2008, 10:05 PM	(permalink)
saumaun	bump! happy easter, btw

24th March 2008, 01:38 AM	(permalink)
blueroomelectronics	Such as the LM2940 __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

24th March 2008, 06:05 AM	(permalink)
saumaun	Ah, so basically I would have to have a low-dropout 5V regulator with a supply of over 5.5V in batteries? Therefore, I could have my mystery hand-crank, 5-6 batteries and an LM2940 between the batteries and the charging cable? (well, knowing my luck, I have it completely messed up) You guys know your stuff!