# Linking parallel port with electronic equipments??

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Is it possible to link up electronic equipments -eg : a simple light bulb with the parallel port to switch circuits on and off? I know how to program in vb as well so will that help? I am hoping to use my computer to control some circuits... please help

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yes, theoretically, this should work, practically, yes, why not? but it will not be easy.

firstly; you will have to get the correct lead, with suitable ends, then, the port which you are connecting your equipment into, will be connected to the motherboard, so make sure, no electrical in, as they are likely to ruin your whole computer.

so you have to use your port as the output. a rare few ports actually dont have a power output, only a connection, although the majority to produce some kind of output power,

however, most hardware ports dont emit an actual electric current, they produce soley the correct signal;

e.g. a speaker ports produces sound electronic patterns, not a voltage and the data seperately, your USB digital camera, gets power from the computer, but only when there is an input of digital images, so you couldnt trick the computer into forcing an output current that way.

more powerful outputs, such as the screen, powerful speaker systems, printers, scanner etc etc, all have their own voltage input systems, via the mains, NOT via the hardware ports on the computer.

you cannot power high voltage circuits from your computer.

i dont know how you are going to 'trick' your computer into producing a voltage current output, opposed to a data output

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There is a book out there, Easy Robot builders, or something, which teaches you all you need to know, diagrams and all the info for running things from the parallel port.

I'll get ya an exact name of the book later, not handy right now.

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damn, stupid me, i didnt really register when you said "parallel port", sorry, yes you can 'trick' the parallel port, you cannot draw high voltages outta it, but enough to run a circuit, try searching this on google, there are normally diagrams and stuff, if i find a good site, i'll post it, but it will have to wait till lata

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Is it possible to link up electronic equipments -eg : a simple light bulb with the parallel port to switch circuits on and off? I know how to program in vb as well so will that help? I am hoping to use my computer to control some circuits... please help
yes of course you can, and quite easily

youll need a buffer chip 1stly though, I personaly reccomend the 74245 as that will work both ways too, so you can use the 8 data line as inputs as well, depending on the control state, itll be more than happy using the +5v supply rail too

there are Open Chathode varieties too, for direct relay drivers, but I prefer the regular 74245 and transistor drive my relays (its your choice).

hope that helps

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ahhh....so thats not so simple....but by the way i still don't get how i can trick the parallel port, you see i am not an expert at vb soo.....

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it is simple, its almost pin for pin, as thwe 74244 and 245 were designed for the centrionics par port.

and you dont "trick" it, you acces the chip registers using the mem map, set the correct flags (input/output) then present your binary code of which pins youde like as a 1 or a 0 (a +5volts or a 0volts).

theres nothing complicated

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I've got a similar question:

For a serial cable, can the computer detect when two of the pins are connected? In my case, I want to connect two wires to a spst mometary switch so that a program can detect when it is depressed.

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What is the signal voltage in USB? 5v?

I want to make some LED sound (signal as sent by computer rather than air) sensitive lights but use analog signal from usb... Possible?

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i am making a parallel port controlled device. i have a doubt. can we connect both input and output to an EPP or ECP mode at the same time.

Posible????

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