Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Is there a short tutorial describing simple, low voltage circuit switching using the LPT port?

I know it could be done using USB or RS 232 relays, but I would like to assemble it with (buying) minimum or none electronic components, except things I have: an LPT cable, a LED diode or a fan, and a 12 V adapter.

share|improve this question
"a LED diode or a fan" How can you have one or the other? Is this a student project, perchance? – HikeOnPast Oct 29 '12 at 20:35
Yes it is, although I'm not a student, or is this homework or test. – JJ_Jason Oct 29 '12 at 20:37
Where do you even find a computer with a parallel port these days? – Theran Oct 30 '12 at 16:57
Now that's a constructive comment.. – JJ_Jason Oct 30 '12 at 17:54
up vote 1 down vote accepted

This is one way:

Parallel Port Controlled LEDs

share|improve this answer
by copying inpout32.dll you'll opening your door to many bad things. – Standard Sandun Oct 29 '12 at 20:52
Would you mind elaborating? – JJ_Jason Oct 29 '12 at 20:56
Source code for that DLL is freely available. You can check it and compile yourself, if you are concerned with safety. – Al Kepp Jan 27 '13 at 23:28

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.