Hi, I’m a pretty big noob on circuit design, I’m good at math thouh and I am familiar with both AC and DC equations. My project is to use an arduino pro mini to control a high powered infrared led to control TVs. The reason I am using a high powered LED is because I don’t want the led to have to point directly at the tv as its going to be in a fixed location, and I also kind of want the additional experience of working with a higher powered LED as I think a regular LED is just too simple. So I’m using a 940nm LED 5W 1.3v-1.5v forward current of 1500mA and a max current of 3000mA. I’m thinking of putting 2000mA-2500mA through as it certainly will not be on constantly except for when holding volume up and down. So i wanted to use a single power supply to power the arduino and LED, what is my best choice? I’ve been leading toward using a switching mosfet. I already have a 12v 3A power supply, was wondering how to split it to both the arduino and the transistor. Do I need a voltage regulator board too? And a more general question, can you control both voltage and current with a voltage regulator? ignorant huh? Current must reduce after passing through the mosfet, as it is not always passing current. So how do I separate this voltage current ratio in general? Thanks a million
Since you say yourself you are still a big noob, I would suggest you start working with a current consumption an order of magnitude less. In other words 100- 300 mAmp and see how that fares. First, investigate the web how other people make LED driving circuits. LEDs are current driven devices. So to prevent them burning up you need to limit the current. There are regulation circuits to do that.
Voltage regulators cannot prevent it from burning up. Voltage regulators do not care how much current a load takes. If it takes too much then the voltage regulator will overheat because it burns up the excess voltage on it’s input. Or the regulation fails and the output voltage drops below the designed value.
“Current must reduce after passing through the mosfet”
Mosfets are electronic voltage driven switches. Well, in the way you want to use them. Not sure why you think it must only reduce the current. It must stop it! Otherwise you’ll get very poor IR pulse emissions. Some IR radiation between strong pulses. That’s bad for signal to noise ratio. If it only reduces current then it will burn the energy (voltage times current times period) inside the mosfet up as heat and will likely burn out, or need a big heat sink. Stopping the current completely is far more energy and thermal efficient.
Sorry for my lack of ability to communicate, great job understanding my nonsense, I think I wrote that post after working an overnight, I seem more of a noob than I actually think I am haha. I’m not even sure what I meant about the mosfet, probably was hoping I could make a buck converter without lots of support circuitry, which is just silly. Thanks for the info about the LED drivers, that will probably be easier/cheaper than designing a buck converter. I don’t know why I didn’t settle on a standalone driver in the first place. Thanks for your assistance!
Yeah, working overnights are often more detrimental. Been there.
There are switching regulator IC-building blocks that have the support circuitry inside and can be used to make both a buck or a boost converter with minimal part. Or with the proper wiring and passive components at the right place can be used as a voltage or current regulator. Often suggestion or examples for those are given in the datasheet or application notes written by the manufacturer. I don’t know one at the top of my head but if you start searching you’ll run into them I’m sure.