How come this circuit operates differently (lights up/dims) depending on the npn transistor used??
When using:
npn = 2n4401, LED = ON, base = 0.7V
npn = 3904, LED = OFF, base = 0V
More confusingly, why does it light up at all? If the base reads 0.7V, then doesn't the voltage divider rule (between 560 and 5k resistor) completely COLLAPSE!! How can this happen??
When using:
npn = 2n4401, LED = ON, base = 0.7V
npn = 3904, LED = OFF, base = 0V
More confusingly, why does it light up at all? If the base reads 0.7V, then doesn't the voltage divider rule (between 560 and 5k resistor) completely COLLAPSE!! How can this happen??
Rich (BB code):
5v
|
|----------------|
| |
| 150
560 |
| |
| /
|------------|/ npn
| |\
| \
5K |
| |
| |
|---------------|
|
gnd