So, when I PWM an transistor with 1/2 the ammount off volts as the collector recieves, the emitter shall output 1/2 volts that the emitter is recieveing .
PWM still digital pulse signal (0 or 5 Volt only) but "Duty cycle" change is effect to average "Output power"
then the switch mode transistor circuit still work on PWM signal
this page is good example to see what different on 10% 50% and 90% PWM signal,
http://www.netrino.com/Publications/Glossary/PWM.php
if circuit is active HIGH,
LED will ON while logic HIGH
and OFF if LOW
but PWM is blinking at high frequency, then human eye will see the "dimmed" light instead of blinking
at PWM 100% (255 in value) is always ON and most bright and dimmed if lower %PWM