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I have seen many smart home systems that enables you to hook up your appliances to your PC and control it right from your desktop. They are all very comprehensive and above all very expensive. I was thinking of doing something similar without using a micro controller ( i know they are the fashion today but a layman has an aversion to it ). I kept thinking and thinking and tey suddenly it stuck me...the good old PARALLEL port!!!!...

I have used it to light an LED using a c program when i was 15...then i left it as soon as i layed my hands upon my first microchip pic project.

But i thought i better dust it back up...come one guys..let us do it....

Step 1: Basic Ideas of a Paralell Port

Everybody knows what is parallel port, where it can be found, and for what it is being used. the primary use of parallel port is to connect printers to computer and is specifically designed for this purpose. Thus it is often called as printer Port or Centronics port (this name came from a popular printer manufacturing company 'Centronics' who devised some standards for parallel port). You can see the parallel port connector in the rear panel of your PC. It is a 25 pin female (DB25) connector (to which printer is connected). On almost all the PCs only one parallel port is present, but you can add more by buying and inserting ISA/PCI parallel port cards.

the Pin outs are simple...
pins 2-9 are the 8 data pins which we will be using to control up to 8 switches.

Step 2: The Circuit

Parts List

IN4148 Diode - 1
6V Relay -1
1KOhm Resistor - 1
202Kohm Resistor - 1
BC547 Transistor -1 (BC548 Will also do)
LED - 1
DB25 Male connector ( Usually comes with a 25/18 wire cable)
6V Power Supply - 1 ( I used a old charger from Nokia, It worked pretty well)
Working Board - 1 ( you can also do it in Christmas tree style...but i prefer doing it in a board )
Necessary Wiring


Pins 18-25 Usually comes shorted together in the connector itself..else do it in the connector and use a single wire to the ground to minimize complications...

Step 3: The Software to Run It.....

I am not venturing into the details of the programming..

Google for inpout32.dll to get the details :)

The Program
There are only three steps?
yes of course!!!...isn't that wonderful???
It's clearly an amazing project, but with only three steps I don't have enough detail to actually do it.
Nice. Just so that you know (in case you don't already know), also the serial port can be used, it has less outputs (only two, but four inputs) but it can still be used for some simple projects.
i hav seen such projects, but never tried one. u have any details on how its done?
yeah, first of all attached is a picture of the pinout of the male side of the connector. Pins 2 and 3 are for receiving and transmitting data (for advanced circuits) so we will not use them, pin 5 is ground, and the other pins are all high/low I/O lines. Pins 1,6,8,9 are inputs (meaning you can give +5V in and the software will detect this), and pins 4,7 are outputs (meaning you can switch the high/low state from the software). An important note is that the serial port doesn't always operate at 5V, it will detect also 5V on pins 1,6,8,9 but the output of pins 4,7 is usually about 10V on a desktop computer. Regarding the controller software I only know how to make it for Linux operating system, since I guess you use Windows I think you'll just have to google around.
Well, evidently the attachment didn't come, here is a link to the picture of the pinout: http://www.western-data.com/products/images/9-pinout.jpg
What id you want to manipulate more than two appliances? no details?<br />
Hi,<br /> <br /> I&nbsp;Promise to come up with a better explaining instructable of this project real soon..this was my first one...<br />
Could you put a picture to see how the final implementacion ended? Thanks!
The eight switches, can they be turned on and off seperatly?
yeah sure...there are 8 different data-line in the parallel port..you can program to activate anyone separately.. (i am sorry if am vague...i promise t update the instructables real soon with full detailed instructions)
hi! it is an amazing project. I have all the parts,but I haven't got idea how to connect the 6v rely ( can you explain me how to connect the 5 connectors of the rely?). Have you got any picture of the real circuit or the end project to see how to solder the components?
A relay is actually a switch that can be switched on electrically.I hope the relay you have has the following layout, circuit -> | | AC OUT -> | AC IN-> | | the first two pins connect to the circuit. the middle pin must be the AC IN. Connect the phase there and take out the out put from the innermost pin. Be careful when using AC :)
Where is the "house control" part? It would be nice if you showed us exactly how to hook it up to room lights, appliances, devices, etc.
Could i use this to power other devices too?
yeah.....it depends on the rating of the relay used...u can power upto 5A appliances...if u can lay your hands on a heavy duty (industry use) relay it can handle upto 15A...(That is hell a lot of power)
Lol I was thinking of making a 'Bank' Style Alarm and Locking door with like a metal bit with solenoids Automatically locking when the alarm goes off and Lights etc
Great Instructable. I'm sorry I didn't find this before I bought a Parallel Port Relay Board.<br/>I couldn't get the Lamp.zip to work on my WinXP laptop. Here's an alternative that worked for me:<br/><a rel="nofollow" href="http://neil.fraser.name/software/lpt/">http://neil.fraser.name/software/lpt/</a><br/>It's called lpt.exe. The VB6 version works too.<br/>Thanks! : )<br/>
Nice work Can u upload or mail the source code of this project. Best regards Shahid shahid@deef.com
You say it can accommodate up to eight switches. How many did you incorporate into your nifty red box?
3...i only have 3 lights in my room (...a patience too...to wire up the same circuit 3 times :) )
this is cool but does the software work with windows xp and can this handel a 120v light
Sure it does...i am using windows xp...i tested it also in vista home... And it can handle a 120v light for sure...the relay is actually a switch that makes and breaks a contact...equipment we connect to relay is completel isolated from the circuit...

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