Rufus, I cannot add more wires because all the wire that can fit are already in the kick pipes leading from the engine room to the helm. I do have some spare conductors but I want to make best use of them. That is why I want to come up with a way to use one wire for two functions.
The basic concept is to use a wire that is normally floating to transmit two active conditions, one signaled by 12 VDC on the wire, the other signaled by Grounding the wire. The signal is simple, powerful and unequivocal, and uses minimum power. There must be a way to use it at the other end in a similar way. This is what prompted the Question Two, how to use one wire to signal either low oil pressure or high engine temp. Question One, how to turn a latching relay on or off with a 12 VDC or Ground pulse on one wire as a way to control a load that is powered by the buss on or off without having continuous current in the signal wire (as in using it to control a normal relay) or constantly energizing a relay, thus minimizing the current demand. Using a 12 VDC or Ground on one wire to control a load also adds the ability to turn a load on or off from several different locations around the boat such as remote and local. That is the essence of both questions. How can we use a single wire, quiescently floating, by putting it to 12 VDC or Ground, to send a signal or turn a load off and on using minimum power in the simplest way. In some places I do use light lines to activate a relay that operates a load. For example, I use telephone wire with four conductors to turn two vent fans and one fuel pump on and off from the helm. But I loose local control this way. If I turn the fuel pump on in the engine room then go up on deck, I have to go all the way back into the engine room to turn it off. It would be nice to be able to control the loads from anywhere the wires go. I believe there must be some clever way to do it and there is so much high-grade brain power on the list I'm betting it can be done. As for having others working on my boat, that is not an issue. Nobody else works on my boat. If my heirs are lucky, I will someday write an operating manual before I meet Davy Jones. Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W > [Original Message] > From: Rufus Laggren <[EMAIL PROTECTED]> > To: <[email protected]> > Date: 7/28/2008 9:43:39 PM > Subject: Re: [Liveaboard] 1 wire relay cntl - fr. 12 VDC buss > > Norm, > > I may be a coward, but I think I'd go KISS here and pull more signal wires when and if needed someday; CAT-x cable really isn't that hard to install. I know all electrolytic (and because of the large value needed for good power boost that's what we're talking here I think) capacitors like to degrade and fail and although I'm sure you can get really good diodes, I'm equally sure you can get pretty mediocre ones much easier so you need somebody to spec the components - somebody current enough in that field who knows which logo is trustworthy. And you're looking at grief if you ever want to replace one out in tim-buk-too because the application numbers will like have changed in the mean time. > > Also wires are much easier for Joe Schmoe to understand and troubleshoot; you can't always depend on being the one to service the system nor can you count on getting a top flight tech. My guesstimate is that 1/2 of the wannabees out there won't actually damage you, 1/2 of those do adaquet basic change out work, 1/2 of those do good scripted service work (step through fixed decision trees), 1/2 of those actually understand the systems and 1/2 of those can actually figure out and rebuild systems. And if you find one of the last type who actually does WHAT he said WHEN he said he'd do it, he's worth almost anything he asks for. IOW, good help is hard to find - don't set the bar high when you don't have to. <g> > > Rufus > > -- > Be Yourself @ mail.com! > Choose From 200+ Email Addresses > Get a Free Account at www.mail.com > > > _______________________________________________ > Liveaboard mailing list > [email protected] > To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard > To subscribe send an email to [EMAIL PROTECTED] > > To unsubscribe send an email to [EMAIL PROTECTED] > The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ > > To search the archives http://www.mail-archive.com/[email protected] > > The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
