The problem with these easy inverters are that both outputs switches turn on before the other switches off
And that's this circuit fix with an extra transistor and resistor to keep the other switch base of until it turns off
The delay between the switches may change with deference in the switches used base saturation voltage
The lower the base saturation voltage the wider the delay
The base saturation voltage cannot be higher than the switches that they have to keep the base off in order for them to work
