# PCB Heaven

## General Category => Digital discussion => Topic started by: Mosquito on March 25, 2008, 15:40:28 PM

Title: Counter 7 Segment circuit help
Post by: Mosquito on March 25, 2008, 15:40:28 PM
I have the attached circuit and i wonder: The 330 Ohm resistors that i have chosen for the limiting current from IC to 7 seg is enough or should i choose a bigger resisotors?
Title: Re: Counter 7 Segment circuit help
Post by: FrED on March 28, 2008, 00:13:02 AM
For led i know 1K is ok. Is this like leds?
Title: Re: Counter 7 Segment circuit help
Post by: kam on March 28, 2008, 00:40:16 AM
You need 30mA
You can calculate the resistance using the ohms law. You do not provide the voltage so i cannot help you more.

And calculate it here: http://www.pcbheaven.com/handbook/calculus/index.php?calc=ohm (http://www.pcbheaven.com/handbook/calculus/index.php?calc=ohm)
Title: Re: Counter 7 Segment circuit help
Post by: FelIX on March 28, 2008, 01:29:53 AM
For led i know 1K is ok. Is this like leds?

Lower than 1K. They will be not bright enough.
Title: Re: Counter 7 Segment circuit help
Post by: Erkeli on March 28, 2008, 09:49:01 AM
Depends on the voltage
Title: Re: Counter 7 Segment circuit help
Post by: Mosquito on April 02, 2008, 22:48:47 PM
it is 5 volts
Title: Re: Counter 7 Segment circuit help
Post by: kam on April 03, 2008, 08:13:51 AM
R=U/I = 5/0.02 = 250

330 ohm is ok.
Title: Re: Counter 7 Segment circuit help
Post by: Mosquito on April 07, 2008, 19:10:06 PM
Okey dokey!

BTW: I love Dr.Calculus!