Parallel vs Serial Was: NEWBIE - Hooking up multiple power supplies to a circuit
- Yeah, me too. I would go the Parallel port route. It's easier ... more direct. I've connected relays (thru drivers) to my parallel port ... and had QBasic programs control them.To really do a good "serial" job would be to run maybe a PIC microprocessor with it's UART going to your PC's serial port. The PIC would then interpret the characters coming over the serial line and determine what your PC wants to have happen. Then, the PIC can turn ITS output ports on and off in response .... turning your devices on and offCurtisGet your free newsletter at
http://www.ezinfocenter.com/3122155/NL----- Original Message -----From: David LevasseurSent: Friday, November 29, 2002 8:08 AMSubject: RE: [Electronics_101] NEWBIE - Hooking up multiple power supplies to a circuitHello,First of all, you can't hook up your serial port directly to your transistor. You need to build a RS232 interface.That interface could be made with a microcontroler or with discrete logic part.On a other way, it would be a lot easier to do this by using your parallele port.You simply need isolation between the port and the transistor. You can use a 74hxxx buffer or any other isolating device.Then, a simple program accessing the port or even ASCII comment sent directly to the port through hyperterminal would do.Regards,David-----Original Message-----Hey there everyone,
From: ridiculicity [mailto:ridiculicity@...]
Sent: Friday, November 29, 2002 2:49 AM
Subject: [Electronics_101] NEWBIE - Hooking up multiple power supplies to a circuit
I have a very basic question but I can't figure out the answer.
Basically, I want to use a transistor as a switch on a 12V DC motor
and I want some kind of digital signal ( most likely a line from my
serial port ) to control the on/off functionality. I'm not sure how
to hook this up.
I'm assuming that the +12V source goes on the collector of the
transistor and the negative goes on the emitter. Then the line from
the serial port would connect right to the base. That's where my
question pops up. Shouldn't there be a ground for the TTL signal? Is
it possible that the TTL signal just switches the transistor and then
vanishes? Shouldn't there be a way for the signal to go from computer
to transistor and then back to computer?? I just don't understand..
If anyone could help me, I'd sincerely appreciate it.