Ahoy All, Both Ken and Rufus have come up with what look like simple solutions to how to control a latching relay using one wire.
Rufus' plan involves using a one-coil DPDT latching relay. One end of the coil is connected to the control line, and the other to the moving contact of one of the poles. One stationary contact connects to 12 VDC and the other to Ground. If the movable contact is on 12 VDC and the control line goes to 12 VDC nothing happens, but if the control line goes to Ground a pulse of current will flow to move the relay to the opposite condition. Visa-versa for the other condition. Magnetic hystersis is relied on to make the relay get all the way over to the other condition, but a capacitor may help it across. Ken's plan is much like many folks's initial ideas using steering diodes, but to stop current flow in the quiescent condition he uses two capacitors instead of diodes, one capacitor each going from 12 VDC and Ground to the two coils or one end of a single coil relay.. He has added a resistor in series with the capacitors to control surge current. The juice stored in the capacitors pops the relay from one state to the other but doesn't allow any current flow in the quiescent state. I think both of these solutions will work. When I get back to my boat (I am in Ft Myers FL now taking care of my Mom) I will test both concepts. Congratulations to both Ken and Rufus. When something doesn't go according to plan, ordinary men say "Oh, poopie!", while extraordinary men say, "Well, that's interesting!" These two gentlemen are extraordinary men. Now, how about the second question. How do I use one wire to send both a low oil pressure signal or high engine temp signal to the instrument panel? I would need a lamp on the panel to indicate each condition and a buzzer. The transmitting switches both put their signal wire to ground (Murphy gauges) when activated. Of course, a relay could be used to change that. Power to the alarm circuits goes off when the engine stops, and I can turn off the buzzer at the instrument panel. Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W _______________________________________________ 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
