ray lunder wrote:

I saw this once using an off-on-off 3 pole switch (? it had 6 lugs)
and some diodes but I can't remember where. The switch is connected to
a 2 conductor wire that goes to a lense with two different bulbs in
it. In one switch position one bulb lights, in the other position the
first bulb goes off and the second bulbs lights instead. (the bulbs
could be different wattage or color). In the center position both
bulbs are off. You saved one wire run. Any ideas?

Elementary, dear Watson: Connect diodes in series with the bulbs, so they
only work in one "direction". Depending which of the two wires you connect
to plus and which to minus, one or the other bulb lights.

-H

Heikki wrote:
ray lunder wrote:

I saw this once using an off-on-off 3 pole switch (? it had 6 lugs)
and some diodes but I can't remember where. The switch is connected to
a 2 conductor wire that goes to a lense with two different bulbs in
it. In one switch position one bulb lights, in the other position the
first bulb goes off and the second bulbs lights instead. (the bulbs
could be different wattage or color). In the center position both
bulbs are off. You saved one wire run. Any ideas?

Elementary, dear Watson: Connect diodes in series with the bulbs, so they
only work in one "direction". Depending which of the two wires you connect
to plus and which to minus, one or the other bulb lights.

-H

Its easier than that and it doesnt require diodes. With 6 lugs you are
talking about a 2 pole 3 throw switch. connect the two wires to the
wipper lugs and one bulb to each of the pairs at the ends. There are
no lugs for the center position.

BUT, you really need only a single pole three throw switch because you
only need to switch one of the wires, the other can go to both bulbs
all the time. AND again, you dont need diodes whether you are talking
DC or AC

"jim.isbell" wrote

BUT, you really need only a single pole three throw switch because you
only need to switch one of the wires, the other can go to both bulbs
all the time. AND again, you dont need diodes whether you are talking
DC or AC


If the switch is located at remote point - say on the boat's electrical
panel and the light is for example a 2-bulb steaming light/deck light, then
would your scheme not require 3 wires from the switch to the lights?

I have also seen diodes used - presumably they overcome this problem by only
requiring 2 wires up the mast?

You need two diodes and a Double throw double pole (DPDT) switch with center
off. The switch will have 6 poles. A pair at each end and a pair in the
middle. Connect the middle pair to your DC power and ground. Connect the
end poles diagonally across from each other and run from either end pair to
the lights. I use that method to control the direction of my fuel and water
transfer pumps.

At each of the two lights add a diode in series with the direction opposite
each other as Heikki described.

With 3 wires and a double gang rotary switch you can control 6 lights.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"OldSailor" wrote in message
...

"jim.isbell" wrote

BUT, you really need only a single pole three throw switch because you
only need to switch one of the wires, the other can go to both bulbs
all the time. AND again, you dont need diodes whether you are talking
DC or AC


If the switch is located at remote point - say on the boat's electrical
panel and the light is for example a 2-bulb steaming light/deck light,
then
would your scheme not require 3 wires from the switch to the lights?

I have also seen diodes used - presumably they overcome this problem by
only
requiring 2 wires up the mast?

But remember that you lose about one half volt thru the diode. For
incandescent light bulbs, the change from 12 volts to 11.5 is significant.
Better have bulbs with more than the required range/brightness.

Roger

http://home.insightbb.com/~derbyrm

"ray lunder" wrote in message
...
Va-voom! thanks.

On Tue, 22 Aug 2006 13:26:42 -0400, "Glenn Ashmore"
wrote:

You need two diodes and a Double throw double pole (DPDT) switch with
center
off. The switch will have 6 poles. A pair at each end and a pair in the
middle. Connect the middle pair to your DC power and ground. Connect the
end poles diagonally across from each other and run from either end pair
to
the lights. I use that method to control the direction of my fuel and
water
transfer pumps.

At each of the two lights add a diode in series with the direction
opposite
each other as Heikki described.

With 3 wires and a double gang rotary switch you can control 6 lights.

derbyrm wrote:

But remember that you lose about one half volt thru the diode. For
incandescent light bulbs, the change from 12 volts to 11.5 is significant.
Better have bulbs with more than the required range/brightness.

Or use LEDs as bulbs - they have the diode built in (actually, they *are*
diodes). As a side effect, you get more light for the same amount of
electricity, which translates to a longer battery life. May not be a
problem on a motor boat, but on a sailboat it may make a difference...

-Heikki