How can a transistor help and Arduino from getting fried

[hydrated-narwhal]

Was up fam, I wanted to know, how do you power 22 IR LEDS (total current=7.7 amps!)(3v) without getting the Arduino fried?

I've heard multiple people say to add a transistor, but i still dont understand how a transistor can help handle the high current while helping the Arduino from getting fried.

Can someone explain it to me?Sorry guys, newbie over here

Thanks

[MrMark]

There's a tutorial on transistors here: https://learn.sparkfun.com/tutorials/transistors/all

[DVDdoug]

First, LEDs are "current controlled" so you need a way to limit/control the current. With regular little LEDs you can use a current limiting resistor in series. "High power" LEDs normally use a constant-current switchmode power supply (or driver). This is not an easy thing to build yourself.

You can use a resistor for high-power LEDs but you need a high-power resistor and the resistor(s) waste about as much energy as the LEDs so you need about twice the power (Wattage) and about half the power is wasted heating-up resistors.

but i still dont understand how a transistor

Transistors and MOSFETs are amplifiers. They allow you to control high voltage & current with a lower voltage & current. (MOSFETs almost need no control current.) It's sort-of like the gas pedal in a car. You can control many horsepower with a little pressure from your foot...

A relay is an electromagnetically controlled and electrically-isolated switch. With a relay you can also use a small amount of power to switch much higher power.

[runaway_pancake]

That's the transistor's raison d'être - using a small input current to control a large output current (like a lever and fulcrum).

[LeoDavila]

@hydrated-narwhal

(total current=7.7 amps!)(3v)

Wow! That's a lot of current.
Super simplified:
A transistor (BJT) is a device that takes small current and lets a bigger one flow.
A MOSFET takes a voltage(rahter than current), to turn on, depending on the voltage you apply is the current that'll flow.

For your aplication a MOSFET can be useful, there exists a huge variety of MOSFETS, we need to focus on a "Logic level MOSFET" (Those that can be fully on with a microcontroller)

This can be an example of one you could use, and in coding, it will be especiefied as a normal output and driven as one as well ...

0-24V Top Mosfet Button IRF520 MOS Driver Module For Arduino MCU ARM Raspberry...

Hope that helps !!

[Wawa]

@hydrated-narwhal

how do you power 22 IR LEDS (total current=7.7 amps!)(3v)

That raises questions. No Arduino can handle that amount of current, so you need external hardware. You normally would use that many LEDs in one or several strings, like Christmas lights.
A string of lights would require a higher voltage, but less current, which could be easier on a supply or drivers. If you're talking about power LEDs, then you will likely need constant current drivers, not mosfets. Tell us more about your project.
Leo..

[Grumpy_Mike]

@hydrated-narwhal

Sorry guys, newbie over here

Then why are you trying to do such a difficult project? This is not beginners stuff.

@hydrated-narwhal

how do you power 22 IR LEDS (total current=7.7 amps!)(3v)

You use an external power supply. From that I gather that each LED takes 350mA, at 3V3 it will take 1.155W, so look for at least a 2W driver. That is not a normal LED, that is a power LED, and as such will need a constant current driver on each LED.

What do you want to do with this?
Is it purely for illumination or do you want to modulate the signal in some way?

You need one of these, or an equivalent, for each LED, it is going to be an expensive project.
https://www.digikey.co.uk/en/products/detail/hatch-lighting/LCA004-UNV/19188587?utm_adgroup=&productid=19188587&msclkid=7faf5eff304916acd5803a26c9a4ce36

What part do you see an Arduino playing in this? I can't see where you would need one?

We also need some details about this LED you want to drive. Have you got a part number?

[TomGeorge]

Hi, @hydrated-narwhal
Welcome to the forum.

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Can you please post a link to specs/data of the LEDs?

How will you connect the LEDS?

1. All in parallel?
2. All in series parallel?

Series parallel will save you on current you have to control.

Can you please tell us the application?

Thanks.. Tom...

[TomGeorge]

Hi, @hydrated-narwhal
Is this thread to do with your project?

But WHY do I have to ?!

Yo fam, I have a high current circuit that uses a Arduino to control a transistor. Why do i have to plug the power supply of the high current circuit to the GND pin of the Arduino to make it work? [Screenshot 2023-08-13 194909] [Screenshot 2023-08-13 194939] My thinking is, Since the high current LED circuit has a transistor on it, it cant have current flowing through the Arduino because of the transistor. So why do I need to connect the arduino to the negative side of the high current circu…

Do you have a schematic?

Thanks.. Tom..