How To Build Parallel Port Prototypes

**Hardware Secrets Team** · 10-13-2005, 02:02 PM

There has been a new article posted.

Title: How To Build Parallel Port Prototypes
URL: http://www.hardwaresecrets.com/article/233

Here is a snippet:
"The computer parallel port is the easiest way to control devices outside the PC, like LEDs, lights and even home appliances. In this tutorial we will teach you how to use the computer parallel port to..."

Comments on this article are welcome.

Best regards,
Hardware Secrets Team
http://www.hardwaresecrets.com

robocoder · 02-14-2006, 11:01 AM

Great article. I have fond memories of parallel port projects, and in particular one which controlled a stepper motor; note: this requires 4 lines.

And it probably goes without saying when working with power lines, double check everything you wire up to the parallel port. Better to be careful than risk frying a motherboard and more. (Yup, speaking from experience.)

dansoy · 04-21-2009, 03:36 AM

Hello there, I'm a newbie here, i was just wondering about this diagram:

is it still safe without using a resistor? hehehe im planning to give it a try cause were having a computer interfacing subject and i want to study it in advance...your advices would really help for beginners like me...Thanks!

Olle P · 04-21-2009, 05:09 AM

I'd attach a resistor on the branch connected to ground, to make sure any currents are limited.

Cheers
Olle

dansoy · 04-21-2009, 06:47 PM

oh i see, i'll use 470 ohms...its okay right?

Thanks Olle!

Olle P · 04-21-2009, 11:22 PM

470 ohm is too much. You only have 5V on the pin, dropping at least 2V in the LED. Assuming a target current of 20 mA that gives us 150 ohm. (With higher LED voltage you'll want even less resistance.)

... and those 20 mA will be divided between all LEDs currently active. With all eight active they will probably glow very faint.

Cheers
Olle

10-13-2005, 02:02 PM	#1
Hardware Secrets Team Administrator Join Date: Nov 2004 Posts: 2,952	How To Build Parallel Port Prototypes There has been a new article posted. Title: How To Build Parallel Port Prototypes URL: http://www.hardwaresecrets.com/article/233 Here is a snippet: "The computer parallel port is the easiest way to control devices outside the PC, like LEDs, lights and even home appliances. In this tutorial we will teach you how to use the computer parallel port to..." Comments on this article are welcome. Best regards, Hardware Secrets Team http://www.hardwaresecrets.com

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02-14-2006, 11:01 AM	#2
robocoder Junior Member Join Date: Feb 2006 Posts: 1	Great article. I have fond memories of parallel port projects, and in particular one which controlled a stepper motor; note: this requires 4 lines. And it probably goes without saying when working with power lines, double check everything you wire up to the parallel port. Better to be careful than risk frying a motherboard and more. (Yup, speaking from experience.)

04-21-2009, 03:36 AM	#3
dansoy Junior Member Join Date: Apr 2009 Philippines Posts: 2	Hello there, I'm a newbie here, i was just wondering about this diagram: is it still safe without using a resistor? hehehe im planning to give it a try cause were having a computer interfacing subject and i want to study it in advance...your advices would really help for beginners like me...Thanks!

04-21-2009, 05:09 AM	#4
Olle P Senior Member Join Date: Oct 2008 Sweden Posts: 576	I'd attach a resistor on the branch connected to ground, to make sure any currents are limited. Cheers Olle

04-21-2009, 06:47 PM	#5
dansoy Junior Member Join Date: Apr 2009 Philippines Posts: 2	oh i see, i'll use 470 ohms...its okay right? Thanks Olle!

04-21-2009, 11:22 PM	#6
Olle P Senior Member Join Date: Oct 2008 Sweden Posts: 576	470 ohm is too much. You only have 5V on the pin, dropping at least 2V in the LED. Assuming a target current of 20 mA that gives us 150 ohm. (With higher LED voltage you'll want even less resistance.) ... and those 20 mA will be divided between all LEDs currently active. With all eight active they will probably glow very faint. Cheers Olle