7 Segment LED Power Issue..

Hello! I pretty new to electronics and the arduino. Please don't be cruel to me.. :slight_smile:

I managed to get a 7-segment LED up and running using a 595 Shifter. Works well and counts from 0-9 and back. The issue I have is the brightness of the LED.
I got SC10-21EWA from Kingbright and except for the "digit" LED most of them are dark especially when more then one segment is lit.

Is there any way of increasing the mA?

Thanks for any help!



what value resistors are you using between the 595 and the LED display? 220 ohms on each pin will make things brighter.

The 595 is a shift register, which "shifts" the data from one pin to the next. If your shift register is 'running' then the pins may only be in the high state for a fraction of the time needed to light it up brightly. You might try changing the code to shift the data out once, and then stop the shifting function (rather than looping the shifting code over and over).

There's a really old-school chip that used to be used for 7-segment displays: google "7447 LED" and you will find it. It takes four binary inputs and coverts them to high-current drive signals. With two 7447's and one '595 you could drive two digits of 7 segment displays. The more modern way to do 7 segment displays is to get an I2C driver chip from Maxim that has everything you need to drive 6 or 8 digits... but if you are starting out, I would try stopping the shifting code as above.