ongky70
Newbie level 3
hello all electronic senior
i'm new here, i'm trying to multiplexing 22 digit of seven segment 1 inch.
in my design, i use IC hc4511 bcd to seven segment as the source driver,
ULN2003 to sink the current,
and 3 to 8 decoder that connected to the ULN 2003.
I give resistor 68 ohm to limit the current.
the micro controller was atmega128.
so far I've succeed program all the segment..
my problem is the seven segment is very dull
from my calculation :
I = V(IC)-V(svsgmnt)/ R
I =5V - 3.6 V / 68 ohm =~21mA
i thought 20 mA will give a good brightness. but in the reality,the light is very dull., I've search all around to solve this problem, but i didn't find it..
is this because of im using too many multiplexing of seven segment so the brightness is dull?
any idea to solve this problem?
I really apreciate your feedbacks.
i'm new here, i'm trying to multiplexing 22 digit of seven segment 1 inch.
in my design, i use IC hc4511 bcd to seven segment as the source driver,
ULN2003 to sink the current,
and 3 to 8 decoder that connected to the ULN 2003.
I give resistor 68 ohm to limit the current.
the micro controller was atmega128.
so far I've succeed program all the segment..
my problem is the seven segment is very dull
from my calculation :
I = V(IC)-V(svsgmnt)/ R
I =5V - 3.6 V / 68 ohm =~21mA
i thought 20 mA will give a good brightness. but in the reality,the light is very dull., I've search all around to solve this problem, but i didn't find it..
is this because of im using too many multiplexing of seven segment so the brightness is dull?
any idea to solve this problem?
I really apreciate your feedbacks.