Date: Sun, 27 Oct 2002 14:05:13 -0600 From: GB Clark <gclarkii@vsservices.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: davek@saturn5.com, nbari@unixmexico.com, freebsd-hackers@FreeBSD.ORG, opn5vmf@yahoo.com Subject: Re: i am looking for a 5 volt signal Message-ID: <20021027140513.3a608671.gclarkii@vsservices.com> In-Reply-To: <200210271919.g9RJJFEm091313@apollo.backplane.com> References: <Pine.BSF.4.44.0210270918380.364-100000@blackbox.yayproductions.com> <200210271919.g9RJJFEm091313@apollo.backplane.com>
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On Sun, 27 Oct 2002 11:19:15 -0800 (PST) Matthew Dillon <dillon@apollo.backplane.com> wrote: > > : > :Shouldn't the fact that the signal is in a while loop keep the 5 volt > :signal going? Isn't the parallel port being blasted with the > :value 255 over and over again? > : > :The serial port will not fulfill what i am ultimately trying to achive. I > :am trying to have the parallel port to control 8 relays each turing > :on/off based upon which bit i send out to the port. > : > :.. > :> try using also the serial port and a logical buffer > :> > :> the 5 volt signal is very fast and your multimeter is maybe not to fast > :> > :> > I'm looking for a 5 volt signal. > > Uh guys. Parallel port digital outputs do not generally have a whole > lot of drive. I really doubt a parallel port output could drive a > relay. > > And it's probably TTL level equivalents, not CMOS. Even if you ganged > the output bits together I doubt you would get enough drive out of > them. > > A serial port output (+/-12 but you may see +/-10 or -5 and +12 or other > out-of-spec combinations) is far more likely to be useful in driving > a relay, though again there will not be much drive. It would be far > better to supply the power you need from another source, like a +5V > power supply. Or just get a wallwart with DC output and run it through > a linear regulator. At least then you aren't likely to burn the house > down :-) > > -Matt > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > Two things here... One, most multimeters do not have the senistivity to monitor a pulse like this, they will just see 0 volts. You really need a scope or a probe to see this. Second, you'll can't drive an analog relay off of Pport without a latch or something. A transistor setup would work just fine. Check out http://www.circuitcellar.com/ for stuff that would work... GB -- GB Clark II | Roaming FreeBSD Admin gclarkii@VSServices.COM | General Geek CTHULU for President - Why choose the lesser of two evils? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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