Most of the time it is necessary to simulate circuits on computers to predict with sufficient accuracy what their behavior will be when implemented. However, a good circuit designer wants to have some ...

With a 4k1 collector resistor and 16mA drive into the led, the chosen (read ‘cheapest on ebay’) 6N135 is supposed to beat 1.5μs for both turn on and turn off, with typical figures of 90ns and 800ns.