parallel port help - how to construct that circuit

[thecall]

parallel port help

i have to develop a program in assembly that flashes leds connected with parallel port of the computer..... as far as programing is concerned i can do that but prob is what will be the circuit how to construct that cirduit.plz help

 

[gelidude]

Re: parallel port help

The most simplest circuit would be to simply wire an LED and resistor in series to each parallel port pins going to ground. HOWEVER this has a high risk of damaging you parallel port. I suggest you use a logic IC as a buffer between the parallel port and your LEDs. Have you tried Googling for some circuits, I'm sure there are lots of them on the net as this is usually a favorite topic to discuss and its also simple. Try this one hope it helps.

**broken link removed**

 

[GrandAlf]

parallel port help

I have never had a problem using ULN series chips with built in base resistors. ULN2803 would give you 8 open collector outputs, one for each data line. As these are darlington drivers, there would be very low port loading. Google for connection details/data sheet.