pwm setup

[rusalka]

Can someone point me in the right direction for building a pwm for range of 3.7v to 7.4v input and variable output? Help would be greatly appreciated.

 

[tlocke]

There is a really good pwm mod here on the forum called the evercool.

http://www.e-cigarette-forum.com/forum/battery-mods/114901-evercool-variable-voltage-mod.html

The only problem I see is that all pwm regulators are going to require some voltage differential from vin to vout. So a 3.7 v input is actually too low for most regulators. I believe the regulator used in the evercool thread is a 4.5 v minimum voltage.

 

[Java_Az]

Can someone point me in the right direction for building a pwm for range of 3.7v to 7.4v input and variable output? Help would be greatly appreciated.

For sure need for details like what battery or batteries you plan on using with it. 3.7 volts is a nominal voltage rating for li ion. Real life a fully charged li ion is 4.2 volts. most protection chips cut the discharge off @ 2.75 volts. So as the battery gets used it goes from 4.2 volts to 2.75 volts. Two batteries in series go from 8.4 volts to 5.5 volts. There is also a drop out voltage to consider like tlocke pointed out. So a adjustable range you want would be helpful also. How many amps you want it to handle should be posted also. The more info you can give, the better the chances of you getting help.