PWM and voltage
hterrolle
Posts: 30
hi,
As i am not electronicien i need to anderstand one things concerning the javelin.
When i use the PWM i can said how much inpulse of High and Low.
in the case I send only High i should get 5volt in outpup.
if i send pwm.update(1,1)·, the impulse will send 5v then 0v all the time.
If i connect this to a LED the LED is less britgh. So it look like the voltage is 2.5v.
But in fact is the number of electron how low but the voltage remains 5v.
Is that rigth ?
·
As i am not electronicien i need to anderstand one things concerning the javelin.
When i use the PWM i can said how much inpulse of High and Low.
in the case I send only High i should get 5volt in outpup.
if i send pwm.update(1,1)·, the impulse will send 5v then 0v all the time.
If i connect this to a LED the LED is less britgh. So it look like the voltage is 2.5v.
But in fact is the number of electron how low but the voltage remains 5v.
Is that rigth ?
·
Comments
A white or blue LED would hardly shine at 2.5 V
The relevant parameter for an LED is the average current flowing through it, transformed into light energy. This is very proportional to the "duty cycle".
Note however that the "impression of brightness" we have is NOT proportional to the LED's power but to the logarithm of it - a famous law ("Weber-Fechner") from the 19th century, which - among others - started astrophysics as we know it now
with this PWM statement, you instrcut the processor to alternate between 0 and 5V every 8,68 microsecond, the average voltage is half of offset, 2,5V.
The LEd turn ons and off alternatively for half time, you hacve half the light it delivers normaly.
Regards.
Robert