R2-D2
Member
I just wanted to be sure of the right value.
I have 4 LEDs hooked up to a 3904 transistor. Each LED is lit at 3V, 20mA - I figure the LED resistance is 150Ω while lit - I guess. Series resistor 120Ω. Source is 15 volts. Load to the 3904 collector is therefore [120Ω resistor + (4*150Ω LEDs)] = 720Ω?
So, my base resistor is RB = 0.2 × RL × hFE , about 30k? (hFE is about 200)
Right?
Transistor Circuits
Thanks!
I have 4 LEDs hooked up to a 3904 transistor. Each LED is lit at 3V, 20mA - I figure the LED resistance is 150Ω while lit - I guess. Series resistor 120Ω. Source is 15 volts. Load to the 3904 collector is therefore [120Ω resistor + (4*150Ω LEDs)] = 720Ω?
So, my base resistor is RB = 0.2 × RL × hFE , about 30k? (hFE is about 200)
Right?
Transistor Circuits
Thanks!