Radio Shack has a couple mini-handbooks that have a lot of simple sample
circuits in them. A couple of transistor relay drivers and switches.
You'll also need an 8 bit latch to catch and hold the value written to
the parallel port. You'll have to work out all the loads backwards to
make sure the relay can handle the solenoid, the transitor can drive the
relay and that the transistor ciruit doesn't over draw the latch, but
hey that's the fun of hardware. With that you would have 8 on/off
devices. If that isn't enough, you could add a flip-flop and a couple
And gates to make an addressing scheme where the 8th bit is a
solenoid/address indicator and the lower 7 bits are solenoid or address
indicators. Then you just clone the circuit with minor And gate changes
for each address of 7 solenoids. If you do more than 2 or 3? of those,
you'll need an 8 bit buffer so the latches don't over draw the parallel
port. I would advise going and getting an add on printer board, they
are cheap, just incase you blow up your printer interface.
Todd
> -----Original Message-----
> From: slug@lists.nks.net [mailto:slug@lists.nks.net] On
> Behalf Of Chuck Hast
> Sent: Monday, April 29, 2002 8:00 AM
> To: slug@nks.net
> Subject: Re: [SLUG] Control, I need CONTROL
>
>
> On Sunday 28 April 2002 13:40 L, you wrote:
> > Here's one possible solution:
> >
> > http://www.sealevel.com/catalog/8007.htm
> >
> > This card will give you 32 relay (solenoid?) drivers. Other cards
> > with different I/O specs are available.
> >
> > Sealevel provides Linux driver modules -- source. It's
> very easy to
> > use. Your program talks to the board (telling it which port to turn
> > on/off) by opening a device file (/dev/dio?) and writing to
> it as if
> > it were a flat file using fseek(). You can use python or other
> > scripting languages as long as they have the open() write() and
> > fseek() commands or their equivalents.
> >
> > Now you have CONTROL!
> > Ed.
> >
>
> Ed, and all that replied, thank you. I now have some routes
> to follow. I do have one question, this is my own system so I
> an going to at least start it out on the cheap. (I need to do
> some major sheckle scraping to purchase that card)
>
> I recall having seen control systems using the printer port
> as the control port, which in turn talks to transistor
> drivers and from there to relays. Does anyone have any ideas
> on that one I can build up a lot of boards with transistors
> and relays on them for what one of those boards will cost me,
> later on as the system needs to be more reliable I will go to
> the board right now I would like to build something that is
> not quite so costly and though it may not be as trustworthy
> it will work 90% of the time.
>
> I can visualize the controller part based on such devices as
> 2n2222's and buffers with the 2n2222's driving small relays.
>
> --
> Chuck Hast
> KP4DJT
> kp4djt@tampabay.rr.com
> To paraphrase my flight instructor;
> "the only dumb question is the one you DID NOT ask resulting
> in my going out and having to identify your bits and pieces
> in the midst of torn and twisted metal."
>
>
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