In Reply to: Re: Triac??? posted by Geoff on 03/14/03 at 6:43 PM:
Hello Geoff. I don't know where you found out that the parallel port could provide voltage and current in the amounts you list. If you re-read my earlier reply, I cautioned that the port output should be used only for picking off logic signals which may be then be utilised for whatever purposes you require through an appropriate interface circuit. Interface powering needs are small and usually an "el cheapo" plug-in wall DC supply will serve. I will E-Mail you some literature on parallel ports which also include a number of interfacing solutions. I am confused re your reference to other items you feel that you also require. I suggest that you use relays for your motor switching. Your proposed project has four steps:
1. Control signals from your parallel port.
2. An interfacing circuit which allows the signals in 1. to pull in a relay (s).
3. A simple wiring hookup from the relay contacts to your motors.
4. A software program which will output the parallel port signals when keyboard keys are pressed.
When you have had time to digest the info I am sending you separately, write back again with any queries you may have. I believe that you are not understanding the "building blocks" necessary in implementing your system.