Pages: [1]   Go Down
Author Topic: Tx/Rx leds  (Read 512 times)
0 Members and 1 Guest are viewing this topic.
0
Offline Offline
Full Member
***
Karma: 0
Posts: 200
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello.

I'm designing my custom-duino with rs485 communication. I have  two leds directly connected to pin0 an pin1with 1k resistors to see serial activity.
My question is... do I need transistors to drive leds like shown in this schematic?

www.linksprite.com/upload/file/1294500698.pdf

Thank you very much.
Logged

Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 443
Posts: 23834
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

No. With 1K, there is only ~3mA load on the driving pin.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

California
Offline Offline
God Member
*****
Karma: 13
Posts: 629
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

I would suspect the LEDs would be very dim without the transistor drivers.
Logged


Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 443
Posts: 23834
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Depends on the LED. 15mcd will not be bright, while a 10,000mcd LED will be very bright, even at just 3mA.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Full Member
***
Karma: 0
Posts: 204
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

This may be helpful:

http://arduino.cc/forum/index.php/topic,114357.msg860483.html#msg860483
Logged

0
Offline Offline
Full Member
***
Karma: 0
Posts: 200
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thank you very much
Logged

Pages: [1]   Go Up
Jump to: