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i want to control a motor from my computer..... from printer port and i need
a realy that can be controlled from that...
the current out from printerport is about 0,5mA and the voltage 5V.
You've probably figured out already that's not going to be enough to drive a
relay directly. Use a transistor to switch the higher voltage/current the
relay will need. A 2N3905 with a 1K resistor between the base and
parallel-port signal will switch a relay on when the signal is low. Connect
the emitter to ground and the collector to one side of the relay coil.
Connect your relay power supply (whatever's appropriate for your relay...
usually 12V DC) to ground and the other side of the relay coil. Put a diode
(such as a 1N4004) in reverse across the coil to keep back-EMF away from the
transistor.
_/_ Scott Alfter (address in header doesn't receive mail)
/ v \ send mail to $firstname@$lastname.us
(IIGS(
http://alfter.us/ Top-posting!
\_^_/ rm -rf /bin/laden >What's the most annoying thing on Usenet?
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