Hallo
i connected to digital output a light giving maximum luminosity when 4.7v 100mA
i known digital output current is 40mA so light intensity is low.
i need mosfet and schematic for obtain 5v 100mA current
Thanks
There is something else that you need. You need to be more careful not to destroy the Arduino board.
The 40mA is the maximum current that is allowed for a Arduino Uno (the shortcut current is even higher), but it is safer to use 20mA as maximum.
A led operates with a current not with a voltage, unless it has a internal current limiting resistor. That means you can not use it with 5V. You need a led driver that outputs 100mA.
Is it a car led ?
Do you have a datasheet for the led ?
i not known led type. It is a pochet light rechargeable. I like it's high brightness with low current, this is the way i want to use it.
i checked with multimeter maximum brightness at 100mA with his board. Minimin brightness at 20mA.
I canno't identify board too.
i use arduino nano with supply 4.2v battery and stepup board 5v so i need Led board 100mA powered by the same battery.
From his board i known only vcc and gnd. Can i connect his board to arduino?
Some cheap flash lights rely on the battery to get a certain current to a led. Expensive flash lights have a circuit that outputs the right amount of current, regardless if the battery is full or almost empty.
Without knowing the led or the battery or the step-up board, it is not possible to advise what you should do. It might not be possible.
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Battery is lithium from old Samsung S1.
I used regulated power supply setted at 100mA constant current and keep led on 12h without problem.
So what i need is to obtain 100mA powered by digital output
From his board i known
VccIn 3.6-4.2v
VccOut 100mA
Gnd
Can i use a Mosfet for switch on this board with arduino?
i ordered a 100mA regulator L78L33.
i will use it with IRF520 switch
Hope it will work
That's a 3.3V voltage regulator. You need some kind of current regulator (or current limiting) and you said you need 4.7 volts.
LEDs are "current driven". You supply the correct current and the voltage "falls into place".
Typically with small LEDs you use a resistor to control/limit current, and you need "extra voltage" for the resistor. About double the LED voltage is "nice" but 6V is probably OK for you. LED Resistor Calculator
High power LEDs (1W or more) are usually powered by a special switch mode constant-current supply, so you don't waste power in the resistor and so you don't need a power resistor.
Here is a MOSFET driver circuit. (You can leave-out the diode since you have a non-inductive load.)
You are working your way down a deep rabbit hole. Post either a schematic or hand drawn one as to how you are putting this together. Also links to technical information on the hardware would help. If it is not available a description of each would help. I would suggest you watch a few videos on Ohm's Law that will help you solve your problem.
How much current flows through the LED when you connect it directly to that battery? Is the brightness sufficient?
You suggest to found higher current regulator (5V 200mA) than pullDown to 100 mA with resistor?
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