need help in " realy interfaced with parallel port " circuit
my teacher asked us to make ptoject with parallel port
I fount this circuit in this site
and I have some questions about it
now he used in the circuit a 12v relay .. while he's getting a 5v from the parallel port input pins
in that case he used a 12v power supply
* If the relay was a 5v relay .. I wont need to use any external power supply ?
and why he is using the IC here ?
also in the components there was ( ribbon wires ) are we going to use them between the circuit and the male connector ?
another question is how we connect the relay to work as the bulb switch
can I use the 120v bulb that we connect it to household and replace its switch with the relay ?
finally what can I use to connect the parallel port to my laptop USB ?
I know I've asked alot of things but please help me