Let's say I have a microcontroller in which an output pin controls 100 LEDs through an NPN transistor (with usual circuit setup of NPN emitter grounded, NPN base to GPIO pin through 1K resistor, and NPN collector to LED arrangement cathode and LED arrangement anode to +5V), but all 100 of them must be either on at full brightness or off at the same time. I plan to power the whole circuit with a 5V voltage regulator so that I can connect a 9V battery to it and not have it blow up.
The LED in particular I plan to power is: https://www.futurlec.com/LED/Green_8mm_LED.shtml
I used a wizard at URL **broken link removed** and used the maximum values possible (30ma) since I don't want the LED's to blink at a high speed and I want bright output.
I then go for solution 2 because a beginner will help me with part of my project and the LED's will be scattered all over the place physically.
So the wizard reports the following:
The wizard says: In solution 2:
each 120 ohm resistor dissipates 108 mW
the wizard says the color code for 120 is brown red brown
the wizard thinks 1/4W resistors are fine for your application
together, all resistors dissipate 10908 mW
together, the diodes dissipate 4545 mW
total power dissipated by the array is 15453 mW
the array draws current of 3030 mA from the source.
Given all this, do I need any transistor better than a 2N2222 at the output of the micro? and what low-priced 5V voltage regulator should I use as the middle man between the 9V battery and the circuit? I just think the standard 7805 won't work because its rated for 1A and the wizard says the LED arrangement needs 3A.
Also, due to pricing and need for more full colour for the application, I'm omitting the ultra-bright LEDs.
The LED in particular I plan to power is: https://www.futurlec.com/LED/Green_8mm_LED.shtml
I used a wizard at URL **broken link removed** and used the maximum values possible (30ma) since I don't want the LED's to blink at a high speed and I want bright output.
I then go for solution 2 because a beginner will help me with part of my project and the LED's will be scattered all over the place physically.
So the wizard reports the following:
The wizard says: In solution 2:
each 120 ohm resistor dissipates 108 mW
the wizard says the color code for 120 is brown red brown
the wizard thinks 1/4W resistors are fine for your application
together, all resistors dissipate 10908 mW
together, the diodes dissipate 4545 mW
total power dissipated by the array is 15453 mW
the array draws current of 3030 mA from the source.
Given all this, do I need any transistor better than a 2N2222 at the output of the micro? and what low-priced 5V voltage regulator should I use as the middle man between the 9V battery and the circuit? I just think the standard 7805 won't work because its rated for 1A and the wizard says the LED arrangement needs 3A.
Also, due to pricing and need for more full colour for the application, I'm omitting the ultra-bright LEDs.