I am at present investigating the opening time of automotive fuel injectors. The attached pic shows 3 traces:
Blue: the control signal (Gate) of the transistor that control the injector
Red: the injector current through a 0.05Ohm resistor connected to ground
Brown: the voltage over the transistor that controls the injector (not relevant to this question)
1) How is it that the current stops flowing (red line starts dropping) BEFORE the transistor switches off (blue line drops to 0V)? (It also looks like current starts flowing BEFORE the tranny switches on...)
2) Why is the rising edge of the blue pulse delayed by a tiny amount with respect to the yellow triangle?