I posted my original design yesterday and got many comments about my errors. This is revision 1 of my design. I am now pretty sure I have the load resistors calculated correctly, but still unsure about the base resistor for the transistor.
To find the base resistor value I used the calculator on this site . On the right side of my image you can see I used these values:
- hFE = 100 (Based on comments on my previous post and highlighted on the data sheet.)
- RL = 70 (This where I'm not sure. It doesn't seem to make sense this would impact it.)
- Vcc = 5 V (5 V supply pin on my Pi Zero W)
- Vi = 3.3 V (3.3 V GPIO pin supply)
For reference, the post that I have revised the design was this one here.
My goal is to get as many of these IR LEDs powered off of the 5V supply using the 3.3 V GPIO to control it on/off using the materials I have available (PN2222A transistor, IR333A LEDs).