My Project: 3 series of 5 3.6v Leds, with a switch on each series; powered by 2 9V batteries, with a 27ohm resistor on each series
When I first tested the 2 9V bateries i got ~18.4 volts, more than i expected. I was hoping for exactly 18 volts since that would power 5 leds(5*3.6=18). Because of the extra voltage i put the 27ohm resistors in. Now my problem is that the batteries are putting out <18 volts, reducing the brightness of the LEDs, and this is exagerated by the resistors.
the LEDs i am using:
http://www.lsdiodes.com/shop/index.php?mai...1&products_id=1
http://www.lsdiodes.com/shop/index.php?mai...&products_id=15
http://www.lsdiodes.com/shop/index.php?mai...&products_id=19
They all draw 3.6v, but the white has a current draw of 25 instead of 20.
How can i regulate two 9v batteries to put out exactly 18V? This way i can leave out the resistors. And does the current draw matter?(i.e. 1,2, or 3 series could be on)
The only things i can think of are capacitors or the LM317T, but i have no idea how to apply either. (http://www.radioshack.com/sm-adjustable-voltage-regulator-lm317t--pi-2062601.html)
For the capacitor would i need one rated at 18v, and would it actually work? and how does one use the LM317T to adjust the output voltage to 18v?
If any more info is needed, just ask.
Any help is appreciated.
When I first tested the 2 9V bateries i got ~18.4 volts, more than i expected. I was hoping for exactly 18 volts since that would power 5 leds(5*3.6=18). Because of the extra voltage i put the 27ohm resistors in. Now my problem is that the batteries are putting out <18 volts, reducing the brightness of the LEDs, and this is exagerated by the resistors.
the LEDs i am using:
http://www.lsdiodes.com/shop/index.php?mai...1&products_id=1
http://www.lsdiodes.com/shop/index.php?mai...&products_id=15
http://www.lsdiodes.com/shop/index.php?mai...&products_id=19
They all draw 3.6v, but the white has a current draw of 25 instead of 20.
How can i regulate two 9v batteries to put out exactly 18V? This way i can leave out the resistors. And does the current draw matter?(i.e. 1,2, or 3 series could be on)
The only things i can think of are capacitors or the LM317T, but i have no idea how to apply either. (http://www.radioshack.com/sm-adjustable-voltage-regulator-lm317t--pi-2062601.html)
For the capacitor would i need one rated at 18v, and would it actually work? and how does one use the LM317T to adjust the output voltage to 18v?
If any more info is needed, just ask.
Any help is appreciated.