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RSS > 5v charger source

Rob	#1 21/08/2012 - 20h58 Top
Class : Apprenti Posts : 2 Registered on : 21/08/2012 Off line	with 3 IR 940nm leds, 1.6 max volt what would be an ideal resistor or resistors? I have 15 Ohm 1/4 watt resistors but that wattage isn't enough is it? Thank you for any help, this is my second build. The 1st is a 3 point clip w/ wiimote and 2AA batteries Edited by Rob on 21/08/2012 at 20h58.
Steph	#2 22/08/2012 - 14h41 Top
Class : Moderator Posts : 656 Registered on : 16/11/2007 Off line	Hi, you only have to figure out, if it's a switched-mode or linear power supply. Switched mode power supply: Voltage varies little with load. Model is lighter, because transformer is smaller. Linear power supply: Voltage varies with load, so you have to take into account that these unregulated power supplies usually provides a higher voltage than indicated (about 15-30%). These models are mostly bigger and heavier for the same output than switched- mode power supply's. If he's not older than five years, it will probably be a switched-mode. Most of handy chargers nowadays are switched-mode power supply's. Go for 80mA to drive the LEDs and use the LED assembly wizard.
Rob	#3 22/08/2012 - 16h27 Top
Class : Apprenti Posts : 2 Registered on : 21/08/2012 Off line	It's a switched power supply and great response, thanks for the help!

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