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FreeTrack Forum > FreeTrack : English Forum > Support : FreeTrack Software > power supply is a little different

RSS > power supply is a little different, Effect of different amperage

Tuba2	#1 15/01/2010 - 04h39 Top
Class : Apprenti Posts : 6 Registered on : 14/01/2010 Off line	I would like to use a discarded 3 VDC transformer. However it is rated at 600mA not the recomended 300mA. How does / will that affect the SFH 485P LED's? I used the LED Assembly Wizard and have the following results: Power Supply = 3 V LED Forward Voltage = 1.5 V LED Forward Current = 50 mA (they are rated at 100mA) P: Parallel Assembly Thee 30 Ohm Resistors Total Current in Assembly = 150 mA So will I damage or shorten the life of the IR LED's ? Or should I just go the rechargeable battery rout?
nadrealista	#2 15/01/2010 - 12h20 Top
Class : Habitué Posts : 84 Registered on : 13/01/2010 Off line	Tuba2 @ 15/01/2010 - 05h39 a dit: I would like to use a discarded 3 VDC transformer. However it is rated at 600mA not the recomended 300mA. How does / will that affect the SFH 485P LED's? I used the LED Assembly Wizard and have the following results: Power Supply = 3 V LED Forward Voltage = 1.5 V LED Forward Current = 50 mA (they are rated at 100mA) P: Parallel Assembly Thee 30 Ohm Resistors Total Current in Assembly = 150 mA So will I damage or shorten the life of the IR LED's ? Or should I just go the rechargeable battery rout? It doesn't matter. Transformer will supply needed amount of current (150mA) whatever it is rated (I'm on PC PSU, a lot of Amps). Your LEDs will be just fine I've been distracted while I was assembling. So, instead of making serial connection, I made parallel one. 300mA and none died I noticed error when resistor turn very hot
Tuba2	#3 15/01/2010 - 16h48 Top
Class : Apprenti Posts : 6 Registered on : 14/01/2010 Off line	Many thanks nadrealista. Another thing I was wondering about. Why does the "LED Assembly Wizard" some times give you a parallel circuit and other times a series one if you change the voltage, etc.?
nadrealista	#4 15/01/2010 - 17h53 Top
Class : Habitué Posts : 84 Registered on : 13/01/2010 Off line	Well, I believe it's set to display the best energy efficient way. Let's say you have 5V PSU, 3x LED with Forward voltage of 1.5V and max. current of 100mV (and you want 50mA through it). If you make parallel circuit, you would have 3x(5V-1.5V)0.050A=0.525W generated heat. With serial circuit you would have (5V-3x1.5V)0.050A=0.025W disipation It should be way better to have serial circuit. :) But, you have only 3V. So, there is no choice for you but to go for parallel (or 2 in series + 1 parallel with them)

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