I’m fairly new to electronics but have completed many of the tutorials here and on tronixstuff’s site. I’m currently learning more about transistors but having a hard time figuring out how to choose some for my current project. I’ve searched and found people who said "use transistor for " but I’m not sure how they chose them. I know it partly comes down to how they’re used (PNP/NPN which I understand) but when it comes to power, how do you decide without knowing all the info off the top of your head?
I’m working with some LEDs. Here are the specs:
Forward Voltage (V) : 1.8 ~ 2.2
Reverse Current (uA) : <=30
Max Power Dissipation : 80mw
Max Continuous Forward Current : 30mA
Max Peak Forward Current : 75mA
Reverse Voltage : 5~6V
They’re not very exact or matched, but fine for my needs. I’m fine calculating resistor values for them individually, too.
What I need to do is control various amounts of these at once using PWM for each set of leds.
For example, I want to use 1 pin to light 3 of these at once, another pin to light 6 other leds, and another to light twelve other leds.
How would I go about choosing which transistors to order for my needs? I’m mainly at a loss on how to determine which transistors fit my needs if I can calculate my Volt/Amp needs.